WETLANDS their USE AND REGULATION /VUm- ■■/' 4-.; 7. v.f^^i.b..- ^»i^;?-'77''' ^,l»"SCo^^ X!?.. CONGRESS OF THE UNITED STATES Office of Technology Assessment Washington, D C 20510 i Office of Technology Assessment Congressional Board of the 98th Congress MORRIS K. UDALL, Arizona, Chairman TED STEVENS, Alaska, Vice Chairman Senate ORRIN G. HATCH Utah CHARLES McC. MATHIAS, JR. Maryland EDWARD M. KENNEDY Massachusetts ERNEST F. HOLLINGS South Carolina CLAIBORNE PELL Rhode Island JOHN H. GIBBONS (Nonvoting) Advisory Council House GEORGE E. BROWN, JR. California JOHN D. DINGELL Michigan LARRY WINN, JR. Kansas CLARENCE E. MILLER Ohio COOPER EVANS Iowa CHARLES N. KIMBALL, Chairman Midwest Research Institute EARL BEISTLINE University of Alaska CHARLES A. BOWSHER General Accounting Office CLAIRE T. DEDRICK California Land Commission JAMES C. FLETCHER University of Pittsburgh S. DAVID FREEMAN Tennessee Valley Authority GILBERT GUDE Congressional Resectrch Service CARL N. HODGES University of Arizona RACHEL McCULLOCH University of Wisconsin WILLIAM J. PERRY Hambrecht & Quist DAVID S. POTTER General Motors Corp. LEWIS THOMAS Memorial SIoan-Kettering Cancer Center Director JOHN H. GIBBONS The Technology Assessment Board approves the release of this report. The views expressed in this report are not necessarily those of the Board, OTA Advisory Council, or of individual members thereof. WETLANDStheir use and regulation OTA Reports are the principal documentation of formal assessment projects. These projects are approved in advance by the Technology Assessment Board. At the conclu- sion of a project, the Board has the opportunity to review the report, but its release does not necessarily imply endorsement of the results by the Board or its individual members. ' ru i 1-^ : 3- ; O i a ; m ; D Recommended Citation: Wetlands: Their Use and Regulation (Washington, D.C.: U.S. Congress, Office of Tech- nology Assessment, OTA-O-206, March 1984). Library of Congress Catalog Card Number 84-601014 For sale by the Superintendent of Documents U.S. Government Printing Office, Washington, D.C. 20402 Foreword This report presents the findings and conclusions of OTA's analysis of approaches to wetlands use. Historically, wetlands were considered wastelands and conversion to other uses was actively encouraged. Two trends in recent decades, however, have altered this perception. First, there has been a growing appreciation for the esthetic and recreational qualities of wetlands; and second, there is now a general recognition of the hydrological and ecological services that wetlands provide. In spite of this increased awareness of the esthetic, recreational, and ecological values of wetlands, pressure to convert wetlands to cropland, commercial development sites, and other uses is still significant in certain regions of the country. This presents a conflict between those who want to convert wetlands to other uses and those who feel they should be left in their natural state. Section 404 of the Federal Water Pollution Control Act (1972), now referred to as the Clean Water Act, authorizes the U.S. Army Corps of Engineers (Corps) to regulate the disposal of dredged or fill material into "the waters of the United States," which in- cludes many wetlands. Because this act opened the way for Federal regulation of many development activities that occur in wetlands, the 404 program has been the center of con- siderable controversy. Federal regulation of privately owned wedands through 404 is viewed by some as land-use control, traditionally the legal domain of State and local governments. Others, who view wetlands as a national water resource, argue that the Federal Govern- ment has an obligation to protect those wetlands that are important to the public. OTA undertook this study at the request of the Senate Committee on Environment and Public Works and its Subcommittee on Environmental Pollution. It describes the eco- logical values of wetlands, trends in wedands use, and the effect of Federal and State wedand programs on wetlands. In addition, OTA reviewed the existing scientific literature to pro- vide background information on the ecological services provided by wetlands. Although this report deals broadly with wetlands and their use, many of its findings relate directly to the Corps' 404 program, which is the major avenue for Federal involvement in regulating some activities that use wetlands. Furthermore, because agricultural drainage and clear- ing have been responsible for the vast majority of wetlemd conversions since the mid-1950's, OTA examined in some detail the policies that encourage the conversion of wetlands to agricultural uses. The data available to resolve these issues proved scanty and of highly mixed quality. For example, good data on wedand trends is only available for the 20-year period prior to implementation of the 404 program. Thus, generalizations about the values of wetlands or the effects of Federal programs, while valid to broad policymaking, are often misleading if applied to site-specific situations. However, within the limitations of this uncertainty, this OTA report provides a policy perspective that could lead to more coherent and ration- al policies for managing the competing uses of wetlands. OTA is grateful for the support, assistance, and cooperation received in this assess- ment from many people representing a great diversity of viewpoints on wetland issues. JOHN H. GIBBONS Director Wetlands Advisory Panel William H. Patrick, Jr., Chairman Director, Laboratory for Wetland Soils and Sediment, Louisiana State University Hope M. Babcock National Audubon Society Earl H. Beistline Dean, School of Mineral Industry University of Alaska Charles E. Eraser President Sea Pines Co. Donald W. Oilman Alaska State Senator Laurence R. Jahn Vice President Wildlife Management Institute Joseph S. Larson Chairman, Department of Forestry and Wildlife Management University of Massachusetts Stanley L. Lattin Director of Planning and Economic Development Port of Grays Harbor Jay A. Leitch Department of Agricultural Economics North Dakota State University Ralph Manna, Jr. Division of Regulatory Affairs New York Department of Environmental Conservation William Manning Louisiana Land & Exploration Co. Eric Metz California Coastal Commission Mark Rey National Forest Products Association Laurence Simns President Maryland Waterman's Association Hobart G. Truesdell, II President First Colony Farms Daniel E. WUlard School of Public and Environmental Affairs Indiana University Iv OTA Project Staff — Wetlands Assessment John Andelin, Assistant Director, OTA Science, Information, and Natural Resources Division Robert Niblock, Oceans and Environment Program Manager William Barnard, Project Director Joan Harn, Analyst Daniel Kevin, Analyst Christopher Ansell, Research Analyst Administrative Staff Kathleen Beil Jacquelynne Mulder Kay Senn Principal Contractors and Other Contributors Center for Environmental Studies, North Dakota State University Center for Governmental Responsibility, University of Florida Center for Great Plains Studies, University of Nebraska Center for Wetland Resources, Louisiana State University John R. Clark Ken Cook William E. Davis* ESA/Madrone Warren E. Frayer JACA Corp. Jon A. Kusler Orie L. Loucks National Wetlands Technical Council, Environmental Law Institute R. Wayne Nelson & Associates School of Forestry and Environmental Studies, Duke University Leonard Shabman Shapiro & Associates, Inc. Water Resources Research Center, University of Massachusetts Kathryn M. White, Writer/Editor OTA Publishing Staff John C. Holmes, Publishing Officer John Bergling Kathie S. Boss Debra M. Datcher Joe Henson Glenda Lawing Linda A. Leahy Cheryl J. Manning •OTA staff Contents Chapter Page 1 . Summary 3 2. Wetland Types 25 3. Wetland Values and the Importance of Wetlands to Man 37 4. Wetland Programs That Affect the Use of Wetlands 69 5. Wetland Trends 87 6. Impacts and Mitigation 117 7. The Effects of the 404 Program 141 8. Limitations of the 404 Program for Protecting Wetlands 167 9. Capabilities of the States in Managing the Use of Wetlands 187 Appendix — List of Acronyms and Glossary 199 Index 205 VII Photo credit: U.S. F(s/i and Wildlife Service— L. Ctiilders Photo credit: U.S. F/s/i artd Wildlife Service— E. Laveme Smith Contents Page Introduction 3 Values and Uses of Wetlands 5 The Intrinsic Qualities and Ecological Services Associated With Wetlands 5 Wedand Conversions 5 Trends in Wetland Use 6 Programs and Policies Affecting Wetland Use 7 Federal Programs Discouraging Wetland Conversions 10 Federal Programs Encouraging Wedand Conversions 12 Administration Policies 13 State Wetland Programs 13 Local Wetland Programs 13 Private Initiatives 13 Policy Considerations and Options 13 Policy Considerations 13 Policy Issues 14 Policy Options 14 TABLES Table No. Page 1. Wetland Conversions From Mid-1950's to Mid-1970's 7 2. Major Federal Programs Affecting the Use of Wetlands 9 FIGURES Figure No. Page A. Actual Wetland Conversions 8 B. 404 Permit Statistics, 1981 12 Chapter 1 Summary INTRODUCTION The use of wetlands — the marshes, swamps, bogs, bottom lands, and tundra that comprise about 5 percent of the contiguous United States and about 60 percent of Alaska — is a source of controversy between those who want to convert these areas to other uses and those who want them left in their natural state. Some wetlands can provide natural ecological services such as floodwater storage, ero- sion control, improved water quality, habitat for fish and wildlife, and food chain support. In addi- tion, many wetlands are esthetically pleasing and offer varied recreational and educational opportu- nities. At the same time, these wetlands may pro- vide sites for housing, agriculture, or commercial development. Wetlands are usually characterized by emergent plants growing in soils that are periodically or nor- mally saturated with water.* They occur along gradually sloping areas between uplands and deep- water environments, such as rivers, or form in ba- sins that are isolated from larger water bodies. Of the 90 million acres of vegetated wetlands in the lower 48 States, 95 percent are located in inland, freshwater areas; the rest are coastal, saltwater wet- lands. In addition, it is estimated that nearly 60 percent of the State of Alaska — or over 200 million acres — is covered by wedands. Within the last 200 years, 30 to 50 percent of the wedands in the lower 48 States have been converted 'The Fish and Wildlife Service (FWS) used the term "wedand" in 1952 to describe a number of diverse environments that shared char- acteristics of both aquatic and terrestrial habitats — i.e., lands at least temporarily inundated, but with "emergent" vegetation adapted to saturated soil conditions. Presendy, there are two major Federal defini- tions. One definition was established by FWS for purposes of map- ping and classification of wedands; the second, more restrictive, defini- tion was developed by the U.S Army Corps of Engineers and the En- vironmental Protection Agency for the purpose of regulation. As a result, FWS has estimated that in the mid-1970's there were 99 million acres of vegetated and nonvegetated wetlands in the lower 48 States. In comparison, the Corps estimates that its jurisdiction extends over approximately 64 million acres of wedands. The differences in the interpretation of what constitutes a wetland have led to considerable confusion and a great deal of controversy. Disagreement exists, for example, over whether parts of the Alaskan tundra and drier sections of bottom land hardwoods should be considered wedands. to Other uses by activities such as agriculture, min- ing, forestry, oil and gas extraction, and urbaniza- tion. According to the most recent Federal survey, a net amount of approximately 1 1 million acres of wetlands in the lower 48 States were converted to such other uses between the mid- 1 950 's and mid- 1970's.* This amount was equivalent to a net loss each year of about 550,000 acres, or about 0.5 percent of remaining wetlands. The vast majori- ty of actual losses — about 80 percent — involved draining and clearing of inland wetlands for ag- ricultxiral purposes. Although some wedand losses were due to naturad causes such as erosion, sedi- mentation, subsidence, and sea level rise, at least 95 percent of actual wetland losses over the last 25 years were due to man's activities. The best available information indicates that present national wetland-conversion rates are about half of those measured in the 1950's and 1960's or about 300,000 acres per year. This reduction is due primarily to declining rates of agricultural drainage, and sec- ondarily to government programs that regulate wet- lands use. At this time. Federal policies and programs do not deal consistently with wetlands use. In fact, they affect wetland use in opposing ways. Some policies encourage conversions: tax deductions and credits can significantly reduce wetland conversion costs for farmers. On the other hand, regulatory and acquisition programs discourage conversions. The U.S. Army Corps of Engineers' regulatory program established by section 404 of the Clean Water Act, provides the major avenue of Federal involvement in controlling the use of wetlands by regulating discharges of dredged or fill ma- terial into wetlands. For those activities that come under regulation by the Corps, annual conversions are reduced na- *The analyses presented in this study apply only to vegetated wet- lands. If unvegetated habitats, such as mud fiats, were included, the quantitative estimates describing wedand trends coiJd change by as much as 10 to 20 percent. However, the overall wedand trends in the lower 48 States and the policy options discussed later are not sig- nificandy affected by differences in wedand definitions. 4 • Wetlands: Their Use and Regulation tionwide by about 50 percent, or 50,000 acres of wetlands per year, primarily through project mod- ifications. Because most activities that occur in coastal wetlands are regulated by the Corps and/or State wetland programs, coastal wetlands are reasonably well protected. However, many ac- tivities, such as excavation and traditional clear- ing and drainage for farming and other uses, are not regulated by either the Corps or by most State wetland programs. These activities were responsi- ble for the vast majority of past conversions, espe- cially in inland areas, where 95 percent of the Na- tion's wetlands are located. Inland, freshwater wetlands are generally poorly protected. The current rates of wetland loss are not likely to have catastrophic enviromental impacts in the next few years, but the continued incremental con- version of wedands, especially in certain inland re- gions of the country, could have significant adverse ecological effects over the next few decades. To ad- dress this situation, the Federal Government could play an important role in integrating ongoing ef- forts to manage the Nation's wetlands. Over the next decade existing wedand programs can be integrated in a few successive steps. First, the Federal Government could complete its ongo- ing mapping of wetlands; high priority could be assigned to those areas where development pres- sures are high. Next, the wetlands in different regions of the country could be categorized accord- ing to their relative values. This would enable ex- isting wetland programs to be tailored in a consist- ent and integrated manner to the broad categories of wetlands and to prospective development activ- ities. If deemed necessary, the Government could broaden the scope of different wetland programs (e.g., regulation, acquisition, leasing, etc.) to include the full range of wedand values, rather than continuing to focus on individual values, such as wildlife habitat. By taking these steps, higher value wetlands would receive more protection than wet- lands of lower value. Developers also would have prior knowledge about standards and requirements for converting specific wetland areas, thus simpli- fying the regulatory process. For such an integrated approach to wetlands management, further efforts also would be needed to reduce uncertainties about: recent wetland trends, the ecological significance of additional wetland conversions, and the effect of major pol- icies and programs on wetlands use. A detailed work plan developed by an interagency working group would help to ensure that all required activ- ities are accomplished in a timely manner. Finally, while this plan is being developed. Con- gress may wish to provide additional protection for wedands, especially higher value wedands that may be subject to agricultural conversion. This could be done through acquisition or easements from the Department of the Interior's Fish and Wildlife Serv- ice, or through leases from the Department of Agri- culture's (USDA) Water Bank Program. All of these options can provide comparable levels of pro- tection. For a given level of funding, many more wetlands can be protected with leases than with easements or acquisition; however, leases only pro- vide short-term protection. During the course of this study, data were col- lected from the scientific literature. Government reports, and responses to questionnaires about wet- lands use from 37 out of 38 Corps districts, from 48 States, and from 1 1 out of 20 trade associations surveyed. The Office of Technology Assessment (OTA) also conducted case studies of wetland trends in 13 States and minor studies in 8 States,* and interviewed many Federal and State person- nel and industry representatives. Because agricul- tural activities were responsible for the vast majority of past wetland conversions, agricultural policies were surveyed in somewhat greater detail than were most other Federal policies. As a result of its studies, OTA has identified three issues related to wedands management. First, should Federal involvement in protecting wedands be increased or decreased? Second, should the Fed- eral Government improve its policymaking capabil- ity through a systematic collection and analysis of additional information about wetlands? Finally, should the Federal Government develop a more in- tegrated approach for managing the use of wet- lands? More detailed analyses of the technical and institutional information that relates to these policy options are presented in later chapters of this report. 'Case studies were conducted for Alaska, California, Florida, Loui- siana, Massachusetts, Minnesota, Nebraska, New Jersey, North Car- olina, North Dakota, Rhode Island, South Carolina, and Washington. Minor studies were conducted in Connecticut, Maine, Maryland, Mis- sissippi, New Hampshire, South Dakota, Texas, and Vermont. Ch. 1— Summary • 5 The results of the study are presented in this sum- mary in three sections: values amd uses of wedands, programs and policies affecting wetland use, and policy considerations and options. VALUES AND USES OF WETLANDS The Intrinsic Qualities and Ecological Services Associated With Wetlands Some people value v^etlands for their intrinsic qualities. Their primary motivation for protecting wedands is simply a desire to preserve natural areas for future generations, or because they are often the last areas to be developed. Others value the varied and abundant flora and fauna found in wet- lands and the opportunities for hunting, fishing, boating, and other recreational activities. While rec- reational benefits can be quantified to some extent, the other intrinsic values of wetlands are, for the most part, intangible. For this reason, the justifica- tion for protecting wetlands has often focused on the importance of the ecological services or re- source values that wedands provide, which are more scientificailly and economically demonstrable than intrinsic qualities (box A). The intrinsic qualities and ecological services pro- vided by wetlands can vary significandy from one wedand to another and from one region of the coun- try to another. For example, mangrove swamps, while only of marginal importance to waterfowl, are very important for erosion control along the Florida coast. Some wedands provide benefits that are primarily local or regional in nature; other ben- efits may be national or even international in scope. Because of the many differences between indi- vidual wetlands, the significance of their ecolog- ical services and intrinsic qualities must be de- termined on an individual or regional basis. In making such a determination, the dollar value of the ecological services that wedands provide can sometimes be quantified. The Corps, for instance, estimated that the loss of the entire 8,422 acres of wedands within the Charles River Basin in Massa- chusetts would result in average annual flood dam- ages of over $17 million. However, because the many intrinsic qualities of wedands carmot be quan- tified, it is usually difficult to place generally ac- cepted dollar values on wetlands. Wetland Conversions Wetlands can provide important sites for devel- opment activities such as agriculture, forestry, port and harbor development, oil and gas extraction, housing and urban growth, mining, and water re- source development. Wedand drainage for agricul- tural purposes is particularly widespread in the Lower Mississippi River Valley and in some areas of the Southeast. Some activities, such as peat min- ing and cranberry production, can take place only in wetlands or in former wetlands; other activities may achieve cost savings by using wetlands rather than upland areas. Some wedands lie over natural resources such as oil, gas, and phosphate ore de- posits. For example, unprocessed phosphate ore underlying wedands in coastal areas of North Car- olina may be worth several hundred thousand dol- lars per acre. Although development activities that affect wetlands are probably worth billions of dollars annually, data were not available for OTA to estimate the total net monetary values of these activities as they relate to wetlands. Development activities that involve excava- tion (or dredging), filling, clearing, draining, or flooding of wetlands generally have the most significant and permanent impacts on wetlands and the ecological services they provide. The ex- tent of these impacts varies aunong projects, depend- ing on the scale and timing of the project, the type of wetland affected, and many other variables. In many cases, project impacts can be reduced by re- designing the project or ^y modifying construction timetables. The ability to restore significantly degraded wet- lands or converted areas to their original condition depends on the type of wetland and on the degree to which it has been affected by natural processes or by particular development activities. For exam- ple, former San Francisco Bay wetlands that were formerly used for ^riculture are now being restored by removing manmade dikes that once separated them from the Bay. It is also possible to create new 6 • Wetlands: Their Use and Regulation Box A. — Ecological Services of Wetlands Floodpeak Reduction. — Isolated and flood plain wetlands may temporarily store runoff, and flood plain wetlands may slow the downstream flow of water and provide additional capacity for conveying flood- waters, thus reducing floodpeaks and the frequency of flooding in downstream areas. For example, the swampland in the Cache River watershed in southern Illinois retains about 8.4 percent of the watershed's total runoff during flooding. Water-Quality Improvement. — By temporarily or permanendy retaining pollutants, such as suspended material, excess nutrients, toxic chemicals, and disease-causing micro-organisms, wetlands can improve, to varying degrees, the quality of the water that flows over and through them. Some poUutants that are trapped in wedands may be converted by biochemical processes to less harmful forms. Some pollutants may remain buried; others may be taken up by wedand plants and either recycled within the wetland or transported from it. By temporarily delaying the release of nutrients until the fall, wedands may help pre- vent excessive algal growth in open-water areas in the spring, when nutrient availability from other sources is typically high. Wetlands can retain nutrients on a net annual basis and have been used successfully for secondary treatment of sewage effluents. Food and Habitat. — Wedands provide food and habitat for many game and non-game animals. For some species, wetlands are essential for survival. For instance, many species of waterfowl and freshwater and saltwater fish require wetlands for breeding and nesting. Approximately 20 percent of all plant and animal species listed by the Federal Government as threatened or endangered depend heavUy on wetlands. For other species, wedands serve more general needs. Coastal marshes and certain types of inland, freshwater wetlands achieve some of the highest rates of plant productivity of any natural ecosystem. This high pro- ductivity often supports varied and abundant animal populations within a complex food chain. During the growing season, less than 15 percent of the plant biomass in saltwater marshes is consumed directly by foraging animals. After the plants die, up to 70 percent of the plamt material is broken down into small particles and flushed into adjacent waters, where it becomes a potential food source for estuarine-dependent fish and shellfish. Shoreline Stabilization. — Some vegetated saltwater and freshwater wedands significandy reduce shoreline erosion caused by large waves and major coastal and riverine flooding. For exaunple, in a com- parative study, an unvegetated shoreline retreated at a rate of more than twice that observed for a similar shoreline fringed by a marsh. Ground Water Recharge. — Some wetlands that are hydrologically connected to a ground water system supplement local or regional ground water supplies through infiltration/percolation of surface water. However, the potential for most wetlands to recharge ground water is limited. In general, uplands are more effective recharge areas than wetlands. Trends in Wetland Use Wetland conversion rates, which averaged about 550,000 acres per year for the Nation be- tween the mid-1950's and inid-1970's, vary sig- nificantly throughout the country. On the one hand, conversion rates in the Lower Mississippi River Valley were nearly three times the national average; on the other hand, wetland conversions occurred in coastal areas at rates that were about 25 percent less than inland conversion rates (table wetlands in areas that are not subject to a high de- gree of wave action or swift currents. Most expe- rience at creating new wetlands has been in rela- tively calm coastal environments, where costs range from as little as $250 to over $6,000 per acre. The ability to construct new wetlands or to restore converted ones should not be used as sole justification for converting wetlands to other uses: manmade wetlands do not necessarily pro- vide the same values as natural ones. In addition, it is probably not possible to create new wetlands or to restore them at the rate they have been con- verted to other uses in the past. Ch. 1— Summary • 7 M'-- " ■--•-■^'' - . ^ ^ '^^' ^ --.*"* • k» U)iii \A\\h ^^ ^ ^ P/io(o cred/(. US. Fish and Wildlife Service Wetlands provide food and habitat for many species of fish and wildlife. Waterfowl, in particular, often require wetland habitats for breeding and nesting. Table 1.— Wetland Conversions From Mid-1950's to Mid-1 970's Original acreage nnid-1950's (million acres) Million acres Conversion rate Net loss^ Coastal . Inland . . 4.8 100.0 0.4 11.0 8.3% 11.0% ^Net losses are calculated by subtracting the gains in wetlands (from man- induced and natural causes) from the actual losses of wetlands. SOURCE: Original data from FWS National Wetland Trends Study, 1983. Ninety-seven percent of actual wetland losses (or conversions from wetland to nonwetland areas) occurred in inland, freshwater areas during this 20- year period (fig. A). Agricultural conversions in- volving drainage, clearing, land leveling, ground water pumping, and surface water diversion were responsible for 80 percent of these conversions. Of the remainder, 8 percent resulted from the con- struction of impoundments and large reservoirs, 6 percent from urbanization, and 6 percent from other causes, such as mining, forestry, and road construction. Fifty-three percent of these conver- sions occurred in forested areas, such as bottom lands. Of the actual losses of coastal wetlands, ap- proximately 56 percent resulted from dredging for marinas, canals, and port development, and to a lesser extent from shoreline erosion; 22 percent re- sulted from urbanization; 14 percent from dispos- ing of dredged material or from creating beaches; 6 percent from natural or man-induced transition of saltwater wetlands to freshwater wetlands; and 2 percent from agriculture. Wetland conversions have adversely impacted the environment in some regions of the country. For example, reductions in Pacific-flyway migra- tory waterfowl have been directly correlated to the conversion of about 90 percent of California's wet- lands. While the ecological significance for the Na- tion of wetland conversions over the last several decades is uncertsdn, the environment will undoubt- edly be negatively affected if conversions continue. PROGRAMS AND POLICIES AFFECTING WETLAND USE Wetland use is directly and indirectly affected by a variety of Federal (table 2), State, local, and private programs that were developed, for the most part, during the past two decades. These programs affect wedand use through regulation, acquisition, leasing, easements, and general policy guidance. 8 • Wetlands: Their Use and Regulation Figure A.— Actual Wetland Conversions (mid-l950's to mld-l970's) Freshwater wetlands (in thousands of acres) Saltwater wetlands (in thousands of acres) Urban Agriculture 9 Ottier Open water areas (canals, port and marina development, erosion, etc.) Total saltwater wetland Total freshwater wetland loss (actual): 482,000 acres loss (actual): 14,677,000 acres SOURCE: US. Fish and Wildlife Service National Wetland Trends Study. 1982 Pholo credit: OTA Slatt Wetlands are often attractive sites for real estate development because of their waterside location. This Louisiana housing development near New Orleans, for Instance, is constructed on filled wetlands Ch. 1— Summary • 9 Table 2.— Major Federal Programs Affecting the Use of Wetlands Program or act Primary implementing agency Effect of program /. Discouraging or Preventing Wetlands Conversions A. Regulation: Section 404 of the Clean Water Act (1972) ... U.S. Army Corps of Engineers, Department of Defense B. Acquisition: Migratory Bird Hunting and Fish and Wildlife Service (FWS), Conservation Stamps (1934) Department of the Interior (DOI) Federal Aid to Wildlife Restoration Act (1937) FWS Wetlands Loan Act (1961) FWS Land and Water Conservation Fund (1955) FWS, National Park Service (DOI) Water Bank Program (1970) Agriculture Stabilization and Conservation Service, Department of Agriculture (USDA) U.S. Tax Code Internal Revenue Service (IRS) C. Other general policies or programs: Executive Order 11990, Protection of Wetlands (1977) All Federal agencies Coastal Zone Management Act (1972) National Oceanic and Atmospheric Administration, Department of Commerce //. Encouraging Wetlands Conversion U.S. Tax Code IRS Payment-in-Kind (PIK) Program USDA Regulates many activities that involve disposal of dredged or fill material in waters of the United States, includ- ing many w/etlands Acquires or purchases easements on wetlands from revenue from fees paid by hunters for duck stamps Provides grants to States for acquisi- tion, restoration, and maintenance of wildlife areas Provides interest-free Federal loans for wetland acquisitions and easements Acquires wildlife areas Leases wetlands and adjacent upland habitat from farmers for waterfowl habitat over 10-year period Provides deductions for donors of wetlands and to some not-ior-profit organizations Minimizes impacts on wetlands from Federal activities Provides Federal funding for wetland programs in most coastal States Encourages farmers to drain and clear wetlands by providing tax deductions and credits for all types of general development activities Indirectly encourages farmers to place previously unfarmed areas, including wetlands, into production SOURCE: Office of Technology Assessment, 1983. 10 • Wetlands: Their Use and Regulation Federal Programs Discouraging Wetland Conversions Federal Regulation — The 404 Program Under the River and Harbor Act of 1899, the Corps regulates all activities that could directly af- fect the navigability of rivers and coastal waters used for interstate commerce. In 1972, Congress gave the Corps the responsibility of regulating the dis- charge of dredged or fill material in the Nation's waters under section 404 of the Clean Water Act (CWA). Through this program, the Corps evalu- ates the impacts of proposed development projects on wetlands in light of its review and comments from the Environmental Protection Agency (EPA), the Fish and Wildlife Service (FWS), the National Marine Fisheries Service (NMFS), and the States. If a project's impact on the environment is judged to be significant, the permit application can be denied, the project can be modified to minimize impacts, or the permit applicant can purchase or restore other wetlands to compensate for project im- pacts. EPA also has veto authority over any pro- posed sites for disposing of dredged or fill material. In this way, the 404 program provides broad reg- ulatory authority over wetland use by many types of development activities. The Corps initially interpreted the geographic scope of its new authority to include only tradi- tionally navigable waters. However, after a 1975 decision by the District Court for the District of Co- lumbia in National Resources Defense Council, Inc. V. Callaway, the scope of the 404 program was expanded to encompass "all waters of the United States." The issue of the Corps' expanded jurisdic- tion was hody debated, but left unchanged in a close vote, when CWA was amended in 1977. Many view this broad authority as a significant extension of the Federal Government's constitutional powers that borders on land-use control; others view it as necessary to protect the public's interests in the quality of the Nation's waters. There are fundamental differences in the way Federal agencies and various special interest groups interpret the intent of section 404, which, as stated in the preface to CWA, is to "restore and maintain the chemical, physical, and bio- logical integrity of the Nation's waters" (sec. 101 [a]). The Corps views its primary function in carrying out the law as protecting the quali- ty of water. Although wetland values are consid- ered in project reviews, the Corps does not feel that section 404 was designed specifically to pro- tect wetlands. FWS, EPA, NMFS, and environ- mental groups feel that the mandate of CWA obliges the Corps to protect the integrity of wet- lands, including their habitat values. LIMITATIONS OF THE 404 PROGRAM The Corps' 404 program now provides the major avenue for Federal involvement in regu- lating activities that use wetlands; however, in terms of comprehensive wetland management, it has major limitations. First, in accordance with CWA, the 404 program regulates only the discharge of dredged or fill material onto wetlands. Projects involving excava- tion, drainage, clearing, and flooding of wetlands are not explicitly covered by section 404 and are not usually regulated by the Corps.* Yet such ac- tivities were responsible for the vast majority of in- land wetland conversions between the mid- 1 950 's and the mid-1970's. Rarely have these activities been halted or slowed because of Federal, State, or local wedand regulations. Without more direct government involvement, the conversion of most inland wetlands is likely to continue unabated. Second, the Corps does not have adequate re- sources to regulate activities effectively in all waters of the United States. Instead of case-by-case review, it uses general permits for isolated waters and head- *The regulation of wetland draining and/or clearing operations for agricultural purposes is highly contentious and variable among Corps districts. Some conversions involving the discharge of fill material from ditching operations onto wedands are regulated either individually or under general permits. Individual permits are usually issued with few modifications because of difl'iculties in demonstrating adverse water quality and/or cumulative impacts. Some conversions do not involve the discharge of fill material onto wetlands. Others are not regulated due to failure of the Corps' administration and lax enforcement or because the Corps and EPA may use a narrower definition of wetlands than scientists or environmental groups. Alternatively, farmers may convert potential "wedands" in dry years when wedand vegetation is not present or they may drain wedands through ditches on non- wedand areas. In accordance with present Corps policy, the clearing of bottom lands is not generally regulated by most districts, except in a portion of Louisiana as a direct result of a ruling by the Fifth Circuit Court. However, one Corps district has significantly slowed some large-scale clearing operations, although the extent of its jurisdic- tion is controversial. Ch. 1 — Summary * 11 water areas. Because there are few application or reporting requirements for activities within areas covered by general permits, the Corps has limited regulatory control over these areas. Third, several administrative problems presendy limit the program's effectiveness, including signifi- cant variations in the way different districts imple- ment key elements of the 404 program, the lack of coordination between some districts and other Fed- eral and State agencies, inadequate public aware- ness efforts, and the low priority given monitoring and enforcement. EFFECTS OF THE 404 PROGRAM ON WETLANDS Estimates made by OTA based on the best avail- able information suggest that present conversion rates are probably about 300,000 acres per year.* Approximately 250,000 acres per year result from the unregulated conversion of inland wet- lands, primarily for agricultural use, while 50,000 acres per year result from conversions regulated by the 404 program and State regulatory programs. Of this latter figure, about 5,000 acres are located in coastal areas. According to their own estimates for 1980-81, the Corps authorized projects that, if completed in accordance with the conditions of the permits, re- sulted in the conversion of about 50 percent of the acreage applied for. Data from NMFS for the coast- al wetlands (in the lower 48 States) indicate that the 404 program, in combination with State regu- latory programs, reduced the conversion of coastal saltwater wetlands by 70 to 85 percent in 1981. In addition, some conversions may be deterred sim- ply by the existence of the regulatory programs, and other conversions may be avoided through preap- plication consultations with the Corps. Finally, each year about 5,000 acres of vegetated wetlands are either created or restored for mitiga- tion purposes as a direct result of the "condition- ing" of 404 permits. * Because of uncertainties and variability associated with available data and the extrapolations that were made from these data, these estimates may be off by 10 to 20 percent. EFFECTS OF THE 404 PROGRAM ON DEVELOPMENT ACTIVITIES Developers' objections to the 404 program fo- cus mainly on the delays and costs imposed by the regulatory process. There are probably numerous cases where the regulatory costs to developers have been substantial — in some cases, millions of dollars. But little verifiable data are available to docu- ment the overall impacts of the 404 program on development activities, especially as they relate to costs imposed by other programs and policies (e.g., sec. 10 of the River and Harbor Act, Na- tional Environmental Policy Act requirements. State programs, £md locad ordinances) and general economic conditions. Some developers question the need for a Federal program to protect all wetlands; the congressional intent of section 404 relative to wedand protection; inadequate consideration by regulatory agencies of the value of development activities; inconsistencies in the program implementation by Corps districts; and possible inefficiencies or inequities in program administration, including duplication of State wet- land programs. Many also believe that the market value of wetland areas decreases when they fall within the jurisdiction of the Corps' regulatory pro- gram. All permit applicants bear at least some 404- related costs resulting from permit denials, mod- ifications of projects, permit processing, and processing delays. Of approximately 1 1,000 proj- ect applications per year, slightly less than 3 per- cent are denied; about one-third are significantly modified; and about 14 percent are withdrawn by applicants (fig. B). About half are approved without significant modifications. In 1980 approximately one-third of all issued permits took longer than 120 days to process; in 1983 the average processing time was about 70 days. Less than 1 percent of all per- mitted projects require an Environmental Impact Statement (EIS), which may take several years to complete. Delays in processing permit applica- tions for a relatively few large-scale projects (that represent the bulk of the economic value of all pro- posed development activities) probably account for a substantial portion of the total costs to industry associated with the 404 program. 12 • Wetlands: Their Use and Regulation Figure B.— 404 Permit Statistics, 1981 Permits approved without signifi modification Permits modified substantially to reduce project impacts rmits denied Permits witfidrawn by applicant Total number of permit applications: 11,000/year SOURCES: U.S. Army Corps of Engineers and Office of Tecfinology Assessment. Federal Economic Measures Since Federal outlays for wetland acquisi- tions, easements, and leases total only a few mil- lion dollars a year, economic measures can be used to protect wetlands only on a highly selec- tive basis. An estimated 10 million acres of wetlands in the lower 48 States are protected through Federal ownership, easements, and leases. Federal wildlife refuges also protect about 29 million acres of wetlands in Alaska. Full ownership or easements provide the Govern- ment with the most effective mechanism for directly controlling the use of wetlands. Full ownership is probably most suited for situations where manage- ment of a wetland as part of the system of national refuges, parks, and forests is desired or where the goal is to preserve the wetland in perpetuity, re- gardless of the benefits of potential development ac- tivities. Perpetual easements provide almost the same level of control as full ownership, while the wetlands remain in private hands. Recent Federal costs of wedand purchases by FWS range from $600 to as much as $l,200/acre for some bottom lands. Easements typically cost the Government about $200/acre. Federal funding for wedand acquisition and easements is provided through sale of Migra- tory Bird Hunting and Conservation Stamps (duck stamps) and through the Wedands Loan Act of 1961 and the Land and Water Conservation Act of 1965. Leases can provide a high degree of Federal con- trol for the period of the lease. Through the Depart- ment of Agriculture (USDA) Water Bank Program, authorized by the Water Bank Act of 1970, private landowners or operators generally receive, through lO-year leases, annucd payments of $5 to $10/acre for most designated wetlands and up to $55/acre for adjacent upland areas. Tax writeoffs are given to owners who donate wedands to Government or conservation agencies. Federal Programs Encouraging Wetland Conversions Tax deductions and credits for all types of general development activities provide the most significant Federal incentive for farmers to clear and drain wetlands. They also shift a significant portion of the conversion costs to the general tax- payer. The dollar value of these tax incentives is greater at higher income levels. They include: • first-year tax deductions of up to 25 percent of gross farm income for draining expenses (expenses in excess of this limit may be deducted in subsequent years); • tax deductions for depreciation on all capital investments necessary for draining or clear- ing activities; • tax deductions for interest payments related to draining and clearing activities; and • investment tax credits equal to 10 percent of the installation cost of the drainage tile. Price supports and target prices for commod- ities may have encouraged some wedand conver- sion by setting guaranteed floor prices for some crops grown on converted wedands, but few farm- ers have been enrolled in these programs over the past decade. Other USDA policies that may pro- vide assistance for wedamd conversions take the form of technical assistance and cost-sharing for the construction of a wide variety of conservation projects, loans from the Farmers Home Adminis- tration to finance conversions, and Federal com- pensation through crop insurance for crop losses from flooding in wedand areas. These forms of as- sistance are probably of limited significance in in- fluencing a farmer's decision to convert wedands to cropland. Ch. 1— Summary • 13 Administration Policies The administration's goals with respect to wet- lands are unclear. On the one hand, the Corps has revised its administrative procedures for the 404 program to reduce the regulatory burden on indus- try and to increase the role of the States. Some of these changes may have reduced the level of wet- lands protection provided by 404, although there will never be quantitative data to support this or any other statement made about the effects of these programmatic changes on wetlands. Administra- tion support for State coastal management pro- grams also has been reduced significantly, and no funds have been requested in the past 3 years for wedand acquisition. On the other hand, the Depart- ment of the Interior proposed a bill. Protect Our Wetlands and Duck Resources Act (POWDR), to eliminate some Federal expenditures for some wet- land activities, increase funding to States for wet- land conservation, extend the Wetlands Loan Act for 10 years, and increase revenues for wedand ac- quisition through additional fees for duck stamps and wildlife refuge visitation permits. State Wetland Programs Almost all 30 coastal States (including those bordering the Great Lakes) have programs that directly or indirectly regulate the use of their coastal wetlands. Most inland States do not have specific wetland programs. Through a combina- tion of the 404 program and State programs, most coastal wetlands are regulated reasonably well; inland wetlands, which comprise 95 per- cent of the Nation's wetlands, generally are not regulated by States. Developers often object to the apparent duplica- tion between the 404 prograun and State regulatory programs. However, representatives from most States with wetland programs believe that the 404 program and State regulatory programs complement one another. Corps districts often let State agencies take the lead in protecting wedands, using the 404 program to support their efforts. If certain EPA requirements are met, States can as- sume the legal responsibility for administering that portion of the 404 program covering waters that are not traditionally navigable. Twelve States have evaluated or are evaluating this possibility, and four are administering pilot programs to gain practical experience prior to possible program assumption. Michigan is the only State that has applied for 404 program assumption. In general, most States have neither the capability nor the desire to assume sole responsibility for regulating wetland use without additional resources from the Federal Government; some States would be reluctant to do so even with government support. Local Wetland Programs In some areas of the country, the principal means of wetland protection outside of the 404 program comes from local regulations (including zoning con- trols) and acquisition programs. Private Initiatives Private organizations, such as the Nature Con- servancy, the Audubon Society, and Ducks Unlim- ited, have protected thousands of acres of wetlands through direct acquisition, partial interest, and other means. For example, the Richard King Mel- lon Foundation recently gave the Nature Conser- vancy a $25 million grant toward its efforts to con- serve wetland ecosystems in the United States. Other national environmental organizations and hundreds of local or regional organizations, includ- ing fish and game clubs, have also been active in protecting wetlands. POLICY CONSIDERATIONS AND OPTIONS Policy Considerations Controversy over the 404 program has led to much discussion of different ways of changing the Federal involvement in controlling the use of wet- lands. Decisions about the use of wetlands are not usually simple and straightforward, but involve judgments about: 14 • Wetlands: Their Use and Regulation • the importance of wetlands to society relative to the benefits associated with wetland devel- opment; • the relative significance of current rates of wet- land conversion; • the desirability of temporarily deferring the im- mediate benefits from wetland conversion to avoid the loss of potentially valuable resources; • the adequacy of existing programs and the costs imposed by these programs on Govern- ment, development activities, and society at large; and • the appropriate role of the Federal Govern- ment relative to the role of other levels of gov- ernment and of private organizations. In general, the greater the Federal involvement in controlling the use of wedands, the greater the costs for wetland programs and for developers. Policy Issues OTA has identified three issues related to wet- lands management: 1 . Should Federal involvement in protecting wet- lands be increased or decreased? 2. Should the Federal Government improve its policymaking capability through a systematic collection and analysis of additional informa- tion about wetlands? 3. Should the Federal Government develop a more integrated approach for managing the use of wetlands? These issues are interrelated. For example, if Congress determines that the existing data are ade- quate to resolve issue 1 , it would not be necessary to pursue any policy options addressing issue 2 . On the other hand, Congress may decide to adopt op- tions under issue 2 before attempting to make any changes in the level of Federal involvement as dis- cussed under issue 1 . Developing an integrated sys- tem for managing wedands use, as described under issue 3, would require collecting more data about wetlands, as outlined in options under issue 2. Policy Options Issue 1: Should Federal involvement in protecting wetlands be increased or decreased? Arguments about the desired degree of Federal involvement in managing the use of wetlands can be made from three different positions. First, in favor of increasing the level of Federal involvement, it can be argued that wetlands provide many valu- able natural benefits to the public. Yet, from 30 to 50 percent of this resource has been converted to other uses, and conversions continue. Because most States generally do not seem inclined to fill any gaps in the current Federal regulatory program, a stronger Federal presence at least in those States with weak programs may be indicated. Others argue that wetlands have been converted to other uses at rates of only 0.5 percent a year, while present rates are probably even lower. Con- sidering the great benefits that can derive from wet- land conversions, regulatory costs stemming from delays and permit denials are a high price to pay for preserving a small percentage of the Nation's wetlands. Thus, the level of Federal involvement should be reduced even though wedand conversions might increase as a result of decreased regulation. Third, it could be argued that existing Federal programs, including the 404 program, provide the appropriate level of wedands management and pro- tection overall. To some, existing data might not indicate an urgency to halt all wedand conversions, but wetlands (especially high-value wetlands) de- serve some protection to avoid possible incremental losses over the long term. In addition, the scanty data on recent trends may provide little basis for changing existing policies until more information has been collected. Court decisions about the scope of the 404 program and its implementation by the Corps are also pending. The use of privately owned wetlands is now con- trolled, to varying degrees, through a mix of eco- nomic measures and regulation. Numerous options exist for modifying policy to increase or decrease the present level of Federal involvement in manag- ing and protecting wetlands. Ch. 1— Summary • 75 Issue lA: Options to increase Federal involvement in managing wetlands Federal involvement could be increased by adopting any or all of the following options, which are listed roughly in order of decreasing Federal control over wedands use, program costs, and costs to developers. How significant these changes would be is unknown. A single new wedands statute could be developed to combine existing policies with any of the following options; however, if changes are desired, it would likely be easier to modify existing statutes individually. Option 1 : Broaden the scope of section 404 through legislation. Increase the types of activities covered by sec- tion 404. — Projects responsible for the vast ma- jority of past wetland conversions (excavation, drainage, clearing, and flooding of wetlands) are not explicitly covered by section 404 or regulated by most Corps districts. Increasing the types of ac- tivities covered by section 404 could reduce wet- land conversions resulting from nonagricultural ac- tivities. Agricultural activities are so numerous that it would be impractical to regulate all of them; how- ever, it is probably possible to regulate large-scale conversions. At present, not all clearing operations are regulated and few modifications or denials are made, even on those that are. Explicitly address wetland values in section 404. — Because the term "wetland" is used only once in section 404 and is not defined, the objec- tives of C WA with regard to wetlands are open to interpretation. The regulation of wetland-clearing operations, particularly in bottom land areas, has been the subject of constant controversy. If wet- land values were addressed explicidy in section 404, the Corps would have a clear mandate to consider and protect the integrity of wedands (including hab- itat values) as well as water quality. If this were done, many wetland-clearing operations falling within the Corps' jurisdiction could be controlled. Option 2: Remove the incentive for agricultural conversions. Eliminate tax incentives for agricultural con- versions. — The cost of agricultural conversions to a farmer can be reduced through tax credits and deductions for costs associated with clearing and draining activities. Tax incentives could be reduced or eliminated for these activities if they occurred on wetlands. However, the effect of this change on wetland use would probably vary. In some areas of the country, wetland conversions could become unprofitable; in other areas, conversions probably would still be profitable even without Federal tax incentives. The effects of eliminating these tax incentives would be insignificant to the vast majority of farmers and on the farm economy. For example, deductions for wetland conversions were less than 0.3 percent of all farming deductions in 1980. In addition, because of the relatively large acreage of available cropland (i.e., 365 million acres), neither commodity prices nor farm production as a whole would be noticeably affected over the near term if agricidtural conversion of wetlands were curtailed or eliminated. Nonetheless, elim- inating tax benefits to farmers for wetland conver- sions will never be popular. Increase appropriations for the Water Bank Program. — The Water Bank Program, funded at $8.8 million in 1982 and 1983, preserves wetlands and adjacent uplands covered by the program for 10-year lease periods. Because the program is ap- parently popular with the agricultural communi- ty, additional appropriations would allow increased enrollment and greater coverage of wedands in agri- cultural areas. The program might also be more attractive if payments were increased or adjusted annually in response to changing pressures to con- vert wedands rather than every 5 years, as it is now. Encourage wetland preservation through the Payment-in-Kind Program.— In 1983, USDA in- stituted its Payment-in-Kind (PIK) Program, wherein farmers withdrew cropland from produc- tion in exchange for commodities that would have been produced on the cropland. In fiscal year 1983, approximately 82 million acres of cropland were taken out of production as a result of the PIK Pro- gram. However, many farmers are apparently si- multaneously putting other land, which could in- clude wetlands, into production. If the PIK Pro- gram is used in future years, it may be possible to include special provisions that would encourage the preservation of wetlands. 16 • Wetlands: Their Use and Regulation Option 3: Increase appropriations for acquisition and easement programs. The National Wildlife Refuge System contains over 33 million wetland acres: 4 million are in the lower 48 States and 29 million are in Alaska. The National Park System contains untabulated but substantial wetland acreage. Federal funding for these programs could be increased, and greater pri- ority could be given to wedands in purchasing deci- sions. Federal wedand-related income, such as the fee charged for duck stamps, could be increased to support these programs. Option 4: Increase tax benefits for wetland preser- vation through legislation. Congress could alter Federal taxation policies to increase the attractiveness of donating wetlands or of selling conservation easements to Government agencies or to private conservation groups for the purpose of preservation. While the acreage of wet- lands being protected might increase, the ecologiceJ value of the wedands donated would probably vary. Option 5: Reverse the Corps' 1982 administrative changes to the 404 program. The Corps' recent administrative changes to the 404 program have been designed to streamline the permit process. For example, average processing time for individual permits has been reduced from over 120 to about 70 days. Although the Army con- tends that the level of wetlands protection actually achieved has been unchanged by the administrative measures, anecdotal and qualitative evidence sug- gests that these changes, such as the expanded use of general permits, have generally reduced the amount of potential control over wetland use. However, existing data do not allow quantification of the effects of these administrative changes on wedand trends. Reversing these changes would re- establish the administrative framework for regulat- ing wetland use at levels that existed before the ad- ministration's 1982 regulatory reform initiatives. Option 6: Improve the Corps' administration of the existing 404 program. The efficiency and effectiveness of the 404 pro- gram could be improved by implementing the following measures, which may require modest increases in program funding and personnel. Con- gressional oversight may also be required to deter- mine the extent to which these options are imple- mented by the Corps. Standardize Corps' district procedures. — The Corps' 404 program is implemented by 38 semi- autonomous district offices that often differ great- ly in how they interpret and implement the 404 program. Some inconsistencies could be avoided through continued and increased use of regulatory- guidance letters on presently vague policies, such as those on the mitigation of project impacts. Dis- tricts also could exchange information about suc- cessful solutions to common problems. Improve coordination among Federal agen- cies and between the 404 and State regulatory programs. — Improved coordination, increased use of single public notices, and joint processing of per- mit applications could provide "one-stop shop- ping" for permit applicants and reduce procedural duplication and delays. Procedures of this sort al- ready have been successfully implemented in a few Corps districts. Increase program publicity. — Many people planning development activities on wetlands are unaware of the 404 progrcim and its permit require- ments. Greater public understanding could lead to better planning and result in fewer violations, less damage to wetlands, and reduced costs to devel- opers stemming from delays and fines. Improve monitoring and enforcement. — Many districts make inadequate efforts to monitor for permit violations, particularly in inland wedand areas. Action is often taken only in response to reported violations. This situation could be im- proved by increasing district funding, using per- sonnel specifically for this purpose, and by provid- ing equipment (e.g., observation planes) as needed. A congressional mandate may also be required. Establish reporting requirements for general permits. — The Corps does not monitor activities covered by general permits or the impacts of such activities on wetlands. More complete reporting could be required so that individual and cumula- tive impacts associated with individual projects could be assessed. If reports indicated unaccept- able impacts, permit requirements could be strengthened. Ch. 1— Summary * 17 Issue IB: Options to decrease Federal involvement in managing wetlands If Federal involvement in protecting wetlands ap- pears to Congress to be too great, a number of op- tions could be adopted. Some options reduce fund- ing for Federal programs; others reduce the scope of the 404 program. Legislative action is desired by some who favor extensive and permanent re- forms in the program. The following options for decreasing the level of Federal involvement will also decrease wetlands protection, costs for the Federal Government, and regulatory costs to developers. How great these decreases will be is unknown. Option 1: Amend section 404. In a February 10, 1983, letter to EPA, the As- sistant Secretary of the Army (Civil Works) outlined several possible legislative changes to section 404, including the options below. OTA analysis indicates that any combination of these options that includes either of the first two changes probably would pro- vide a level of Federal wedand regulation and 404- related costs to industry similar to those that existed prior to full implementation of the 404 program. Transfer the 404 program to the States. — Most coastal wetlands are reasonably well regulated by 404 and State programs; most inland wetlands are not. In those coastal States with strong wedand pro- grams, transfer of the 404 program to the States probably would not affect wedand use in a major way. In States with relatively weak or no programs, such an option would reduce control over wedands, especially inland wetlands, unless the Federal Gov- ernment provided large amounts of financial and technical assistance to strengthen State programs. Even with assistance, some States still might not effectively regulate wetland use. Expand the use of general permits to include all projects other than those occurring in tradi- tionally navigable waters. — Since monitoring and enforcement requirements for general permits are usually not a high priority in most Corps districts, development of most wetlands would, for all prac- tical purposes, be uncontrolled by the Federal Gov- ernment. Instead, States would have primary re- sponsibility for regulating the use of most wedands. Eliminate permitting requirements for any in- cidental discharges. — If section 404(f)2 were elim- inated, it would be very unclear whether or not the Corps would be required to regulate discharges of dredged or fill material that are incidental to ac- tivities that convert waters of the United States to a new use. Thus, the clearing of wedands, such as the bottom land hardwoods, would probably be- come less stringendy regulated than it is at present. Make 404(b) 1 guidelines only advisory in na- ture. — Section 404(b)l guidelines are developed by EPA in conjunction with the Corps. Through this change, EPA's role in the 404 program would be significandy reduced and nonenvironmental factors could be used by the Corps to override environmen- tal concerns. Give the Corps sole authority to define "dredged material" and "fill material" and ac- tivities that constitute a discharge. — This pro- vision would eliminate EPA's current legal involve- ment in Corps decisions about what activities and types of fill material, such as garbage, would be regulated. Option 2: Decrease appropriations for acquisition, easement, and leasing programs. The Federal Government spends several million dollars each year for wetland acquisition, ease- ments, or leases. Federal funding for these pro- grams could be decreased; similarly, lower priori- ty could be given to wetland purchases. Either ac- tion would have little effect on industry. Option 3: Rescind Executive Order 11990. Regulations developed by many Federal agen- cies in response to Executive Order 1 1990, Protec- tion of Wetlands, could be rescinded. This would allow, for instance. Federal assistance to farmers for wetland drainage. Issue 2: Should the Federal Government improve its policymaking capability through a system- atic collection and analysis of additional in- formation about wedands? At this time there is uncertainty about current trends in wetland use, the environmental significance of further wedand conversions, and 18 • Wetlands: Their Use and Regulation the current effects of major policies and programs on wetlands. Whether or not additional informa- tion should be collected depends on a judgment about its potential contribution to Congress' poli- cymaking capability and its value to Federal pro- gram administrators. For some people, the avail- able information may be adequate for setting pres- ent and future wedand policy. Further information, while perhaps useful in fine-tuning policies, may seem unwarranted given the cost. In this case, op- tion 1 might be selected. On the other hand, exist- ing uncertainties may make it difficult to isolate realistic policy choices and to determine the effect of these options. For instance, it may be difficult for some to decide what changes, if any, should be made to section 404 without better knowing how the current program has affected trends in wetland use. In this latter case, option 2 could be selected. Option 1: No, current information is adequate. For some policymakers, existing information may be adequate to make present and future deci- sions about wedand policies and programs. Some new information will be collected as the result of existing Federal programs. In particular, FWS is planning to update its analysis of national trends to cover the 10-year period following the mid- 1970's. Also, EPA, FWS, NMFS, and the Corps will continue to conduct research on wedand values. Option 2: Yes, collect additional information. For other policymakers, making decisions about wetland policies and programs may be difficult at this time because of major gaps in technical infor- mation. Past efforts have primarily supported the missions of the agencies conducting the research, rather than the policymaking process. Congress' policymaking capability could be significantly im- proved if the three concurrent research elements described below were undertaken. To ensure that the results produced by these efforts are brought to bear on the overall policymaking process, an in- tegrated plan (with budgets and schedules) for con- ducting and coordinating all these policy-related ac- tivities could be developed by an interagency working group headed by a Federal agency. This information would not necessarily be available un- less Congress takes steps to ensure its collection. Element 1: Determine recent trends of wet- land use. — The FWS's recently completed statis- tical analysis of wetland trends provides informa- tion on wetland use only between the mid- 1 950' s and the mid-1970's. As currently planned, FWS will update its analysis of national trends to cover the 10-year period following the mid-1970's. How- ever, better information on regional trends could be collected to determine where wedand-conversion rates are most critical and where development pres- sures are greatest. Such regional analyses would en- tail an increase in the number of sites surveyed. Element 2: Evaluate the significance of addi- tional wetland conversions. — The extent to which the environment will be degraded by additional conversions of wedands is known only in a few cases. For example, if all the prairie potholes in the upper Midwest were lost, we know that North American duck populations would decrease by about half. On the other hand, we do not know the importance of wedand-derived detritus for estuarine fish and shellfish populations relative to other sources of food, such as algae and detritus from up- land areas. Yet this type of information provides a technical basis for changing levels of protection for specific types of wetlands. A detailed under- standing of all wedand systems in the United States is not necessary; much could be learned from a small number of long-term studies of wetland sys- tems within specific physiographic regions, river basins, or estuaries. Element 3: Further analyze the effect of ma- jor policies and programs on wetlands use. — Ad- ditional analysis by an interagency working group on the effects of Federal and State wedand programs on wetland trends could provide a basis for modi- fying existing programs, especially in light of the results of the two options just discussed. For ex- ample, the Corps could compile more thorough in- formation on project acreages and types of wedands impacted. In addition, a detailed evaluation of the capabilities and limitations of State programs, in- dividually and in combination with the 404 pro- gram, could indicate possible ways of improving the efficency and effectiveness of different programs that have a major effect on wetlands. Ch. 1— Summary • 19 Issue 3: Should the Federal Government develop a more integrated approach for managing wetlands? About 5 percent of the lower 48 States, or about 90 million acres, is covered by wetlands. These wet- lands are geographically dispersed and their relative abundance varies from region to region. In some regions, wedands provide important ecological serv- ices; in other regions, their values are primarily in- trinsic (e.g., wilderness, esthetic, recreation, etc.). Wetlands of widely different value can be found in the same regions. Due to the inherent variabili- ty among wetland values, their wide and variable distribution, and the large number of conversion activities (i.e., a few tens of thousands) that are pro- posed each year, the use of wetlands is difficult to manage. , Federal wetland programs generally deal with wetlands in a piecemeal manner; that is, each program generally focuses on certain ecological services, wetland types, and/or geographic areas. For example, FWS acquisition and easement pro- grams focus mainly on protecting wedands (and up- land areas) that are important for wildlife. How- ever, many wetlands that provide other ecological services, such as flood control, might also warrant acquisition. USDA's Water Bank Program leases valuable waterfowl nesting and breeding habitat in prime agricultural areas of the country. Leasing of nonagricultural areas to protect other ecological services is not within the scope of this program. An integrated approach for managing wetlands could be considered. Option 1: Yes, an integrated approach for manag- ing wetlands use should be developed. This integrated approach would involve "tailor- ing" or adjusting existing acquisition, leasing, or regulatory policies on a regional basis to wetlands of different values and to different development ac- tivities prior to possible wedand conversion. Developing an integrated approach to wetlands management would involve four sequential steps. First, the FWS's ongoing inventory of wetlands would be continued or accelerated. Second, the wet- lands in an inventoried region would be categorized according to their relative values. Third, existing wedand policies and programs would be "tailored" or adjusted according to their category and specific characteristics. For example, higher value wetlands covered by 404 could be stringently regulated through individual permits; lower value wetlands could be covered by less stringent general permits. Fourth, different Federal, State, or local programs could be applied to different wedand categories and types of development activities in a more integrated fashion . This approach has several advantages. High-val- ue wetlands with different ecological services could be given an appropriate level of protection. Agen- cy funding and personnel could be focused on high- value wetlands in different regions of the country rather than all wetlands in general or wetlands that provide a single ecological service. Regulators, de- velopers, and the public would be aware of the sta- tus of the wetlands in their particular areas prior to any proposals to convert them to other uses. De- velopers also would have prior knowledge about standards and requirements for converting specific wetland areas. The time required for processing most 404 permits would be significantly reduced. Finally, decisions about wedand use would be more predictable and consistent. The four steps involved in this approach are de- scribed in more detail in the following discussion. Step 1: Continue or accelerate the ongoing mapping of wetlands by FWS. — At this time, a detailed inventory of 30 percent of the wetlands in the lower 48 States and 4 percent in Alaska has been completed. An additional 5 percent of the lower 48 States and 2 percent of Alaska can be mapped each year at an annual cost of $3.5 million per year. With greater funding, this inventory effort could be accelerated . Step 2: Categorize wetlands. — Once invento- ried, wedands would then be placed in three to five broad categories based on the combined importance of their ecologicEil services and intrinsic values. In about a dozen areas in the United States, wetlands have been inventoried and broadly categorized in this manner. One case, the Anchorage (Alaska) Wetland Plan, places wetlands in four categories: preservation, which precludes any development activities; conservation, which allows limited con- versions with measures to mitigate impacts; devel- opable, which allows complete draining and fill- ing without a permit; and special study, which re- quires collecting additional environmental data to 20 • Wetlands: Their Use and Regulation determine wetland status. Local authorities use this plan to control the conversion of wetlands under a genercd permit from the Corps. Categorizing wetlands would involve weighing and integrating the values of different ecological services within a political rather than strictly scien- tific framework. Therefore, categorization could best be accomplished by Federal policymakers from an interagency working group in cooperation with regional groups composed of State and local offi- cials, wedand scientists, developers, and the general public who would be familiar with wetland values in their respective physiographic regions or river basins. This process also would involve regional public hearings. Step 3: Tailor existing policies and pro- grams. — After categorizing the wetlands in a cer- tain region. Federal, State, or local wedand policies and programs would then be selectively applied by program administrators according to the relative values of different wetlands, as well as the values £ind impacts of potential development activities. For example, wedands covered by the 404 program, de- pending on their natural values, could be individ- u£illy regulated, covered by general permits, or left unregulated. For wetlands that are individually reg- ulated, the procedures used to review permits and mitigate impacts could reflect the relative values of the wetlands, as well as the type, size, and ben- efits associated with development activities. Acqui- sition and leasing programs could be easily focused on high- value wedands identified by the inventory. The tailoring process would not be designed to disallow all further wetland conversions. Instead, the inventory zuid categorization of wedands would provide a management tool for program adminis- trators, developers, and policymakers in making decisions about the use of wetlands based on their relative values. All wetlands in the United States would not have to be mapped prior to the tailor- ing of policies; tailoring would be accomplished as the different regions are mapped. The highest pri- ority could be placed on those areas where many important wetlands are located and/or where con- version pressures are greatest. Step 4: Integrate wetland policies and pro- grams. — Step four would first involve increasing the scope of existing wedand policies and programs to include the fuU range of natural wetland values. For example, acquisition and leasing programs, which now focus primarily on protecting habitats with high wildlife values, could be given program- matic flexibility by Congress to consider all wedsuid values. USDA's Water Bank Program for leasing waterfowl habitat in agricultural regions could be broadened to allow leasing of inland wedands with a range of ecological values in both agricultural and nonagricultural areas. If Congress increased the scope of different wetland programs, the interagency and regional groups organized in step 2 could select the most appropriate policies or programs for managing dif- ferent wedand areas — whether through acquisition, easements, or regulation. For example, unde- graded, high-value wedands could be given a higher level of protection than they now have through di- rect acquisition or easements rather than regula- tion. Combinations of different policies might also be used for some wetlands. For example, if certain kinds of development activities on a privately owned wetland were prohibited within the framework of Federal or State regulations, the owner might be given the option to sell the wetland or an easement to the Federal or State Government. If Congress wished to develop such an integrated approach, the gaps in policy-related information (discussed under issue 2) must be filled. Also, to ensure that all ongoing activities are relevant both to the missions of the involved Federal agencies £ind to the policymaking process in general, an inte- grated and detailed work plan could be developed by the interagency working group. In this way, the Federal Government could take advantage of the collective expertise and interests of the different Federal agencies that deal with wedands. This plan should include a description of ongoing and planned activities, agency responsibilities, coordination pro- cedures, funding requirements, and opportunities for congressional oversight. Above all, the plan would describe in detail the processes that would be used to tailor and integrate wetland policies and programs. This plan, which could be developed over a 2-year period at a cost this study estimates to be about $1 million, could provide an overall framework for wedzuid policymaking that would be stable over several administrations. The develop- ment and implementation of such a plan would re- Ch. 1— Summary • 21 quire a congressioned mandate with accompanying appropriations. Option 2: No. The existing approach for managing wetlands is adequate. Some wetland scientists and many environmen- talists have serious reservations about this in- tegrated approach. While they agree that some wet- lands are more valuable than others, they believe that all wedands should be stringently protected; tailoring would only weaken the protection that wet- lands now have. There is also concern about yet-to- be-developed procedures for implementing the con- cept. For example, wedamds can be ramked accord- ing to their relative importance for single ecological services; however, it is not clear how the multiple ecological services and intrinsic values of each wet- land would be considered and weighed during the categorization process. Important or yet-to-be- discovered services could be overlooked. Also, the relative values of wedands may change over time. Therefore, some wedands, especially those that fall outside the framework of State and Federal regula- tions, might not receive an adequate level of pro- tection. Other institutional concerns focus on the uncertainties about the administration of the tailor- ing process, the potential for controversy and for the use of political influence, and the possible high costs associated with implementing such an approach. OTA recognizes that there are uncertainties about developing an integrated approach for managing wedands. However, if the tailoring con- cept is politically acceptable, it should be possible to establish acceptable procedures for implement- ing the tailoring process effectively. In light of ex- isting uncertainties and concerns about tailoring, it may be desirable first to test the viability of pro- cedures in several regions of the country on a pilot scale prior to making a decision about the desirabili- ty of full-scale implementation. Chapter 2 Wetland Types »-v*»-'»a;*»! •.»-'^0n.>»- «. !^£i./f^'V-" Phofo cred/f; t/.S. Fish and Wildlife Service, Urban C. Nelson Contents Page Chapter Summary 25 Origins of Wetlands 25 Glaciation 25 Erosion and Sedimentation 25 Beaver Dams 26 Freezing and Thawing 26 Activities of Man 27 Miscellaneous Processes 27 Hydrologic Characteristics of Wetlands 28 Wetland Vegetation 28 Major Types of Wetlands and Closely Related Habitats 29 Inland Freshwater Marshes 29 Inland Saline Marshes 30 Bogs 30 Tundra 30 Shrub Swamp 30 Wooded Swamps 30 Bottom Lands and Other Riparian Habitats 30 Coastal Salt Marshes 31 Mangrove Swamps 31 Tidal Freshwater Marshes 32 Geographic Distribution of Wetland Types 32 Chapter 2 References 33 TABLE Table No. Page 3. Locations of Various Wetland Types in the United States 32 FIGURES Figure No. Page 1 . General Distribution of Wetlands of the United States 26 2. Cross-Sectional Diagram of New England-Type Salt Marsh 29 3. Physical Subdivisions 33 Chapter 2 Wetland Types CHAPTER SUMMARY Wetlands, including marshes, swamps, bogs, bottom lands, and tundra, occur along sloping areas between upland and deepwater environments, such as rivers, or form in basins that are isolated from larger water bodies. Wetlands are either periodically or continually inundated by water and genersdly covered by vegetation adapted to saturated soil con- ditions that emerges through any standing water. Most wetlands have formed as a result of past gla- ciation, erosion and sedimentation, beaver activi- ty, freezing and thawing in arctic areas, activities of man, and other processes. ORIGINS OF WETLANDS The U.S. Fish and WUdlife Service (FWS) used the term "wetland" in 1952 to describe a number of diverse environments, typically of high produc- tivity, that share characteristics of both aquatic and terrestrial habitats — i.e. , they are at least temporari- ly inundated and have "emergent" vegetation adapted to saturated soil conditions. While a wide range of environmental conditions exist within this categorization — from salt marshes flooded and ex- posed daily to bottom land forests inundated only during spring flooding — wedands also share similar hydrologic and habitat characteristics. These char- acteristics primarily stem from three interrelated factors: the wetland's origin, hydrology, and vege- tation. Six basic processes are responsible for wetland formation: glaciation, erosion and sedimentation, beaver dams, freezing and thawing, activities of man, and miscellaneous processes (6). Glaciation A principal band of wetiands (fig. 1) — lying along the northern tier of the United States, including Alaska, Maine, New York, Michigan, Wisconsin, Minnesota, North Dakota, and Washington — was formed in three ways as glaciers melted 9,000 to 12,000 years ago. First, the melting of large blocks of ice left by receding glaciers created pits and de- pressions in glacial moraines, till, and outwash. Lakes and wetlands formed where the depressions intersected the ground water table or where fine clay and organics sealed their bottoms and per- mitted the coUection of runoff waters. The majority of wetlands in the Northern United States were formed in this manner. Second, glaciers dammed rivers, often creating glacial lakes, sometimes thousands of square, miles in area. Once the ice retreated, the lakes were drained partially, resulting in extensive low-lying areas with peat deposits. These areas form some of the large wetlands in the once glaciated Northern States. Third, glaciers scooped out and scoured river valleys and soft bed- rock deposits, creating large and deep lakes such as the Great Lakes, and shallow depressions and wetland areas, such as the prairie potholes. Erosion and Sedimentation Another principal band of wedands is found (fig. 1) along the gulf and Atlantic coasts, where sedi- ment has been deposited in the still waters be- hind barrier islands or reefs and in bays and estuaries. Wetland formation is favored by low- elevation topography along the Atlantic and gulf coasts. The sediment deposited behind Georgia coastal marshes, for instance, may be up to 10 meters in thickness and has formed extensive flat or gently sloping topography conducive to growth of wetland plants. 25 26 • Wetlands: Their Use and Regulation Figure 1.— General Distribution of Wetlands of tfie United States Note: Shaded portions incorporate generai wetiand areas. Each dot represents about 10,000 acres. SOURCE: Adapted from Samuel P. Stiaw and C. Gordon Fredine, "Wetlands of the United States: Their Extent and Their Value to Waterfowl and Other Wildlife.' Fish and Wildlife Service, U.S. Department of the Interior, Circular 39, 1956. Major wetlands also are located along the flood plains of low-gradient rivers such as the Mississip- pi. River flood plains are created by the deposition of river alluvium on adjacent lands during floods. Rivers may cut new channels, abandoning old water courses, which may then become lakes or wet- lands. Extensive wetland areas, such as the Mis- sissippi Delta, are found where sediment is de- posited at the mouths of rivers and streams. The deposition of sand, gravel, or silt also can create wetlands along the shores of, or adjacent to, lakes. Vast marshes of this type form along the Great Lakes. Beaver Dams At one time, beaver dams played a major role in forming smaller inland wetlands in the forested areas of the Nation. While beaver populations fluc- tuate due to variability in trapping pressure, their presence can be a major factor in increasing wedand acreage in some regions of the country. For exam- ple, in an analysis of wetland trends in 15 Massa- chusetts towns between 1951 and the 1970's, beaver activity was the third most important cause of in- creases in wetland acreage out of 1 1 identified fac- tors (9). Freezing and Thawing In the Arctic, wedands are created when the Sun melts the surface of frozen organic soils while the underlying soil remains permanently frozen. In ad- dition, frost action segregates rock and soil particles of various sizes and shifts them in such a way that shallow, water-filled basins are formed. Ch. 2— Wetland Types • 27 >*^ .i''^*^ Photo credit: Bob Friedman, OTA staff Waubesa marsh near Madison, Wis., began its development approximately 6,000 years ago with the filling in of a shallow lake created by a retreating glacier. The majority of wetlands in the Northern United States were created by similar processes Activities of Man Wetlands may develop naturally adjacent to resei-voirs, farm ponds, irrigation canals, and in pits and depressions created by mining. Poor drainage due to construction of highways, levees, and build- ings also can lead to the development of wetlands. Finally, manmade wetlands can be created inten- tionally by Federal, State, and local resource agen- cies and by conservation groups in shallow, pro- tected waters. Miscellaneous Processes Wetlands may be formed by other special proc- esses. In the Sandhills of Nebraska and in other areas of the arid West, depressions have been formed by wind action. The Everglades exist because of a flow of ground water and surface water over bedrock at and directly below the surface. In Kentucky, Indiana, and several other States, wet- lands are also found in sink holes and other areas where bedrock has been dissolved by percolating 28 • Wetlands: Their Use and Regulation water. Geologic movements have shaped still other wetlands. Reelfoot Lake in Tennessee, for exam- ple, was formed by the sudden sinking of the earth from earthquakes. Similarly, San Francisco Bay was formed by movement along the San Andreas Fault. HYDROLOGIC CHARACTERISTICS OF WETLANDS Wedands may be located on the transitional slop- ing areas between upland and deepwater environ- ments where the water is shallow and calm enough for emergent vegetation to grow. Wetlands also may form in basins that generally are isolated from larger water bodies. These basins: 1) are either at or below the ground water table, or 2) because of poor drainage, retain much of the water that flows into them. The interaction among the hydrologic regime, the wetland topography, and its underly- ing substrata (e.g. , soU) largely controls the general characteristics of a wetland and most, if not all, of the ecological services that it performs. The two hydrologic characteristics that have the greatest influence in ultimately determining the habitat values of a wetland are the depth of the water and the paf fern of fluctuation of water depth (8). The average depth of water varies greatly among wetlands. Bogs, for instance, typically are saturated to their surfaces, but rarely have stand- ing water. In contrast, a wooded swamp or deep marsh may have standing water several feet deep. Annual fluctuations in water level also vary wide- ly, ranging from those that are wet year-round, to those inundated irregularly for only a fraction of the year, to those flooded and exposed daily by tidal action. One of the most important factors influenc- ing average water depth and patterns of fluctua- tion is the source of water, whether from direct sur- face runoff of snowmelt, from a river during spring flooding, or from tidal action in coastal areas. Climate, in addition to influencing the source of water — precipitation, snowmelt, and flooding — also determines seasonal patterns of drying. In the prairie-pothole region of the United States, for in- stance, shallow wetlands may dry out completely in some years. WETLAND VEGETATION A diversity of plant forms is found in wetlands, ranging from deciduous trees to rooted floating plants, such as water lilies. Depending on the soil type, water availability, water quality, and temper- ature patterns, the dominant plants in wedand areas may be mosses, grasses, sedges, bulrushes, cattails, shrubs, trees, or any combination of these. A com- mon distinction among wetland types is the vege- tation type: trees or shrubs dominate swamps; grasses, sedges, cattails, and bulrushes dominate marshes; and mosses and lichens dominate bogs. With the exception of the severe, limiting effect of high salinity on plant type, water depth and fluc- tuation are perhaps the dominant physical factors influencing the type and distribution of plants. Plants often have a narrowly defined tolerance for hydrologic conditions. In a typical New England salt marsh, for instance, Spartina alterniflora (salt marsh cordgrass) dominates the water's edge; as the marsh gains elevation, Spartina patens (salt- meadow cordgrass), and then Juncus (rushes) dom- inate the marsh (see fig. 2). In a freshwater marsh, a typical progression from deep to shallow water would include hard-stemmed bulrush, narrowleaf cattail, and broadleaf cattail. Bald cypress, black willow, willow oak, and swamp chestnut oak are representative species found in a bottom land hard- wood forest, from the areas most regularly flooded to those irregularly inundated. Ch. 2— Wetland Types • 29 Figure 2.— Cross-Sectional Diagram of New England-Type Salt Marsh (from Miller and Egler, 1950) Tidal marsh ■ Spartina Alterniflora lower border Normal high tide Normal low tide Diagrammatic cross-section of the upland-to-bay sequence, showing the characteristics of the major vegetational units. Vertical scale much exaggerated. SOURCE: H, T. Odum, B J. Copeland, and E. A. McMahan, Coastal Ecological Systems of ttte United Stales, vol. 2 (Wastiington, D.C.: The Conservation Foundation, 1974). MAJOR TYPES OF WETLANDS AND CLOSELY RELATED HABITATS Although FWS has developed a comprehensive system for classifying wetlands, for the purposes of this general discussion, OTA has distinguished be- tween very broad types of wetlands using more ver- nacular terms. The primary factors distinguishing these types of wetlands are: 1. location (coastal or inland), 2. salinity (freshwater or saltwater), and 3. dominant vegetation (marsh, swamp, or bog). Inland Freshwater Marshes Inland freshwater marshes may occur at any lati- tude but are not common at very high altitudes. Their water depths generally range from 6 inches to 3 feet. Marsh vegetation is characterized by soft- stemmed plants, grasses, sedges, and rushes that emerge above the surface of the marsh. They in- clude such common plants as water lilies, cattails, reeds, arrowheads, pickerel weed, smartweed, and wild rice (3). 30 • Wetlands: Their Use and Regulation Inland Saline Marshes Inland saline wetlands occur primarily in shallow lake basins in the Western United States. They are usually saturated during the growing season and often covered with as much as 2 or 3 feet of water. Vegetation is mainly alkali or hard-stemmed bul- rushes, often with widgeon grass or sago pondweed in more open areas (13). Bogs Bogs occur mosdy in shallow lake basins, on flat uplands, and along sluggish streams. The soil, often consisting of thick peat deposits, usually is saturated and supports a spongy covering of mosses. Woody or herbaceous vegetation, or both, also may grow in bogs. In the North, leather-leaf, Labrador tea, cranberries, and cotton grass often are present. Cyrilla, persea, gordonia, sweetbay, pond pine, Virginia chain fern, and pitcher plants grow in southern bogs, which are found on the Southeast- ern Coastal Plain. These bogs are more common- ly known as "pocosins" (13). Tundra Tundra is essentially a wet arctic grassland dominated by lichens (reindeer moss), sphagnum mosses, grasses, sedges, and dwarf woody plants. It is characterized by a thick, spongy mat of living and undecayed vegetation that often is saturated with water. Its deeper soil layer or permafrost re- mains frozen throughout the year; the surface of the tundra is dotted with ponds when not complete- ly frozen. In Alaska, wet tundra occurs at lower elevation, often in conjunction with standing water; moist tundra occurs on slightly higher ground. An alpine tundra or meadow, similar to the arctic tundra, occurs in high mountains of the temperate zone (10). Shrub Swamp Shrub swamps occur mostly along sluggish streams and occasionally on flood plains (13). The soil usually is saturated during the growing season and often is covered with as much as 6 inches of water. Vegetation includes alder, willows, button bush, dogwoods, and swamp privet. Wooded Swamps Wooded swamps occur mostly along sluggish streams, on flood plains, on flat uplands, and in very shallow lake basins. The soil is saturated at least to within a few inches of its surface during the growing season and often is covered with as much as 1 or 2 feet of water. In the North, trees include tamarack, white cedar, black spruce, balsam, red maple, and black ash. In the South, water oak, overcup oak, tupelo gum, swamp black gum, and cypress are dominant. In the Northwest, western hemlock, red alder, and willows are common. Northern evergreen swamps usually have a thick ground covering of mosses. Deciduous swamps fre- quently support beds of duckweeds, smartweeds, and other herbs (13). Bottom Lands and Other Riparian Habitats Riparian habitats, those areas adjacent to rivers and streams, are most commonly recognized as bot- tom land hardwood and flood plain forests in the Eastern and Central United States and as stream- bank vegetation in the arid West. Riparian ecosys- tems are unique, owing to their high species diver- sity, high species densities, and high productivity relative to adjacent areas (1). Bottom lands occur throughout the riverine flood plains of the Southeastern United States, where over 100 woody species occur. Bottom lands vary from being permanently saturated or inundated throughout the growing season at the river's edge to being inundated for short periods at a frequen- cy of only 1 to 10 years per 100 years at the uplands edge (7). On the lowest sites that are flooded the longest, most frequently, and to the greatest depths, bald cypress, tupelo gum, button bush, water elm, and swamp privet are most abundant. As eleva- tion increases (and flooding frequency and depth decrease), overcup oak, red maple, water locust, and bitter pecan occur. Nuttall oak, pin oak, sweet gum, and willow oak appear where flooding occurs regularly during the dormant season but where water rarely is present at midsummer. Sites nearest the high-water mark, which are flooded only occa- sionally, have shagbark hickory, swamp chestnut oak, and post oak (4). Ch. 2— Wetland Types • 31 Photo credit: U.S. Fish and Wildlife Service Bottom lands occur throughout the riverine flood plains of the Southeastern United States. They vary from being permanently inundated at the river's edge to being inundated for only short periods at a frequency of 1 to 10 years per 100 years at higher elevations Riparian habitats in the arid West are scattered widely along ephemeral, intermittent, and perma- nent streams that commonly flow through arid or semiarid terrain. Woody vegetation associated with these wedands includes willows and alders at higher elevations; cottonwoods, willows, and salt cedar at intermediate vegetations; and salt cedar, mesquite, cottonwoods, and willows at lower elevations (5). Coastal Salt Marshes Salt marshes alternately are inundated and drained by the rise and fall of the tide. Because the plants and animals of the marsh must be able to adjust to the rapid changes in water level, salinity, and temperature caused by tides, only a relatively small number of plants and animals are able to tolerate these conditions. Thus, there is a high degree of similarity in the kinds of species present. Plants of the genus Spartina and the species J^un- ctis and Salicornia are edmost universal in their occurrence in U.S. salt marshes (12). Mangrove Swamps Mangrove is a term denoting any salt-tolerant, intertidal tree species. In the United States, man- groves are limited primarily to Florida coastal areas. Large mangrove-swamp forests are found only in south Florida and are especially extensive along the protected southwestern coast (2). On the northwest Florida coast, black mangrove occurs mostly as scat- 32 • Wetlands: Their Use and Regulation tered scrublands. On the eastern shore of Florida and along the Louisiana coast, mangroves are found behind barrier islands and on the shores of protected coastlines. Tidal Freshwater Marshes Tidal freshwater marshes occur in virtually every coastal State but are most abundant in the estuaries of the mid- Atlantic coast and along the coasts of Louisiana and Texas. Dominant intertidal plants include a mixture of grasses and broadleaf species, such as arrow arum, spatterdock, pickerel weed, and arrowhead, which form rather complex multi- layered plant zones. The upper marsh may have from 20 to 50 species of grasses, shrubs, ferns, and herbaceous plants (11). GEOGRAPHIC DISTRIBUTION OF WETLAND TYPES The various wetland types described in the pre- vious section are distributed unevenly across the United States. The regions of the United States with high concentrations of the various types are iden- tified in table 3. The regions described are based on Hammond's Physical Subdivisions (fig. 3), which are the same as those used in Chapter 5: Wetland Trends. Table 3.— Locations of Various Wetland Types in the United States Wetland type Primary regions States Inland freshwater marsh Dakota-Minnesota drift and lake bed (8); North Dakota, South Dakota, Nebraska, Upper Midwest (9); and Gulf Coastal Minnesota, Florida Flats (4) Inland saline marshes Intermontane (12); Pacific Mountains (13) Oregon, Nevada, Utah, California Bogs Upper Midwest (9); Gulf-Atlantic Rolling Wisconsin, Minnesota, Michigan, Maine, Plain (5); Gulf Coastal Flat (4); and Florida, North Carolina Atlantic Coastal Flats (3) Tundra Central Highland and Basin; Arctic Alaska Lowland; and Pacific Mountains Shrub swamps Upper Midwest (9); Gulf Coastal Flats (4) Minnesota, Wisconsin, Michigan, Florida, Georgia, South Carolina, North Carolina, Louisiana Wooded swamps Upper Midwest (9); Gulf Coastal Flats (4); Minnesota, Wisconsin, Michigan, Florida, Atlantic Coastal Flats (3); and Lower Georgia, South Carolina, North Carolina, Mississippi Alluvial Plain (6) Louisiana Bottom land hardwood Lower Mississippi Alluvial Plain (6); Louisiana, Mississippi, Arkansas, Atlantic Coastal Flats (3); Gulf-Atlantic Missouri, Tennessee, Alabama, Florida, Rolling Plain (5); and Gulf Coastal Georgia, South Carolina, North Carolina, Flats (4) Texas Coastal salt marshes Atlantic Coastal Zone (1); Gulf Coastal All Coastal States, but particularly the Zone (2); Eastern Highlands (7); Pacific Mid- and South Atlantic and Gulf Coast Moutains (13) States Mangrove swamps Gulf Coastal Zone (2) Florida and Louisiana Tidal freshwater wetlands Atlantic Coastal Zone (1) and Flats (3); Louisiana, Texas, North Carolina, Virginia, Gulf Coastal Zone (2) and Flats (4) Maryland, Delaware, New Jersey, Georgia, South Carolina SOURCE: This table is based on maps from Samuel P, Shaw and C. Gordon Fredine, "Wetlands of the United States: Their Extent and Their Value to Waterfowl and other Wildlife, " Fish and Wildlife Service, US Department of the Interior, Circular 39, 1956. Ch. 2— Wetland Types • 33 Figure 3.— Physical Subdivisions Atlantic Coastal Zone Gulf Coastal Zone Atlantic Coastal Flats Gulf Coastal Flats Gulf-Atlantic Rolling Plain Lower Mississippi Alluvial Plain Eastern Highlands 8 Dakota ■ fylinnesota Drift and Lake-bed Flats 9 Upper Midwest 10 Central Hills and Plains 11 Rocky Mountains 12 Intermontane 13 Pacific Mountains Scale 1-17,000.000 100 200 300 400 Miles CHAPTER 2 REFERENCES Brown, Sandra, Brinson, Mark M., and Lugo, Ariel E., "Structure and Function of Riparian Wet- lands," Strategies for Protection and Management ofFloodplain Wedands and Other Riparian Ecosys- tems, proceedings of a symposium sponsored by the U.S. Forest Service, in Callaway Gardens, N.J., Dec. 11-13, 1978. Clark, J. R., "Coastal Ecosystem Management" (New York: John Wiley & Sons, Inc., 1970), pp. 660-665. CouncU on Environmental Quality, "Our Nation's Wetlands," an Interagency Task Force Report, 1978, p. 70. Frederickson, L. H., "Lowland Hardwood Wet- lands: Current Status and Habitat Values for Wild- life," Wetland Functions and Values: The State of Our Understanding, proceedings of the National Symposium on Wetlands, P. E. Greeson, J. R. Clark, and J. E. Clark (eds.), Nov. 7-10, 1978. Johnson, Roy R., "The Lower Colorado River: A Western System," Strategies for Protection and Management of Floodplain Wetlands and Other Riparian Ecosystems, proceedings of a symposium sponsored by the U.S. Forest Service, in Callaway Gardens, N.J., Dec. 11-13, 1978. Kusler, J., "Our Wetland Heritage: A Protection Guidebook" (Washington, D.C.: Environmental Law Institute, 1983). National Wetlands Technical Council, Workshop Report on Bottomland Hardwood Wetlands, held at Lake Lanier, Ga., June 1-5, 1980. National Wetlands Technical CouncU, "Scientists' 34 • Wetlands: Their Use and Regulation 10 11 Report," National Symposium on Wetlands, Lake Buena Vista, Fla., Nov. 6-9, 1978, p. 32. New England/Massachusetts Case Study, OTA contractor: Water Resources Research Center, University of Massachusetts, Amherst, 1983. Odum, E. P., Fundamentals of Ecology, 3d ed. (Philadelphia: W. B. Saunders Co., 1971), pp. 380-383. Odum, W. E., Dunn, M. L., and Smith, T. J., Ill, "Habitat Value of Tidal Freshwater Wetlands," Wetland Functions and Values: The State of Our Understanding, proceedings of the National Sym- posium on Wetlands, P. E. Greeson, J. R. Clark, and J. E. Clark (eds.), Nov. 7-10, 1978. 12. Odum, H. T., Copeland, B. J., and McMahan, E. A. (eds.). Coastal Ecological Systems of the United States, vol. 2 (Washington, D.C.: The Con- servation Foundation, 1974). 13. Shaw, Samuel P., and Fredine, C. Gordon, "Wet- lands of the United States: Their Extent and Their Value to Waterfowl and Other Wildlife," Fish and Wildlife Service, U.S. Department of the Interior, Circular 39, 1956. Chapter 3 Wetland Values and the Importance of Wetlands to Man Illustration credit: US- Fisti and Wildlife Service, Alderson Magee Contents Page Chapter Summary 37 Attitudes Toward Wetlands 37 Intrinsic Values of Wetlands 39 Wetlands as Natural Areas 39 Wetlands for Recreation and Education 41 Other Intrinsic Values 42 Ecological Services or Resource Values of Wetlands 43 Floodpeak Reduction 43 Shoreline Erosion Control 46 Ground Water Recharge 47 Water Quality Improvement 48 Fish and Wildlife Values 52 Climatic and Atmospheric Functions 60 Chapter 3 References 61 TABLES Table No. Page 4. Summary of Input-Output Studies 51 5. Selected Commercial or Sport Fish and Shellfish UtULzing Coastal Marshes as Nurseries 56 6. Endangered Wetland Species on the Federal Endangered and Threatened Species List 57 7. Game and Fur AnimeJs Identified by State Game Managers as Found in Wetlands ■; . 58 8. The 10 Most Recreationally Important Marine Fish in the United States in 1979 Ranked by Number of Fish Landed 58 9. The 15 Most Important Fish and Shellfish Harvested by U.S. Fisheries in 1980 59 10. Wetland Plant Productivity 59 FIGURES Figure No. Page 4. Relationship Between Wetland Processes and Values 44 5. General Pattern of Duck Distribution in North America 53 Chapter 3 Wetland Values and the Importance of Wetlands to Man CHAPTER SUMMARY Some people value wetlands for their intrinsic qualities. They may wish to protect wetlands simply out of a desire to preserve natural areas for future generations or because they are often the last areas to be developed. Others value the varied and abun- dant flora and fauna that may be found in wetlands, and the opportunities for hunting, fishing, and boating and other recreational activities. While these recreational benefits can be quantified to some extent, the other intrinsic values of wetlands are, for the most part, intangible. For this reason, the justification for protecting wetlands has often fo- cused on the importance of the ecological services or resource values that wetlands provide, which are more scientifically and economically demonstrable than intrinsic qualities. These ecological services include floodpeak reduction, ground water re- charge, water quality improvement, food and hab- itat, food-chain support, and shoreline stabilization. The intrinsic values and ecological services pro- vided by wetlands can vary significantly from one wedand to another and from one region of the coun- try to another. Some wedands provide benefits that primarily are local or regional in nature; other ben- efits may be national or even international in scope. Because of the wide variation among individual wetlands, the significance of their ecological serv- ices and intrinsic values must be determined on an individual or regional basis. The dollar value of the ecological services that wedands provide sometimes can be quantified. The U.S. Army Corps of Engineers, for instance, esti- mated that the loss of the entire 8,422 acres of wet- lands within the Charles River Basin, Mass., would produce average annual flood damage of over $17 million. However, because the many intrinsic qual- ities of wedands cannot be quantified, it is difficult to place generally accepted dollar values on wet- lands. ATTITUDES TOWARD WETLANDS The use of wetlands has become a public policy issue because of conflicts between those who wish to develop them and those who wish to preserve them. Developers, for instance, regard wetlands as prime locations for development because of their typical proximity to open water. Farmers drain or clear wetlands to plant crops in their rich organic soil. While there also are private gains involved, the creation of new jobs or the production of food that results from the development of wetlands di- rectly benefits society. On the other hand, undeveloped wedands have important intrinsic qualities that are esthetically pleasing and provide numerous ecological services. such as flood control, that benefit society. The con- flict between developers and conservationists over wetlands often is viewed as an issue that "involves questions of public good as opposed to private gain" (21). However, the issue is not simply a matter of public versus private interests but of conflicting public interests. The values associated with wetlands were not always widely recognized. For example, in the 19th century when a national priority was placed on set- tling the country, wetlands were considered a men- ace, the cause of malaria, and a hindrance to land development. Through the Swamp Land Acts of 1849, 1850, and 1860, Congress granted to States 37 38 • Wetlands: Their Use and Regulation all swamps and overflow lands for reclamation to reduce the destruction caused by flooding and elim- inate mosquito-breeding swamps. A total of 65 mil- lion acres of wetlands were granted to 15 States for reclamation (81). With increasing concerns about preserving dif- ferent ecosystems, the public's perception of and attitude toward wetlands has changed gradually over the last half century. An inventory of wedands conducted by the U.S. Fish and Wildhfe Service (FWS) in the mid- 1 950' s perhaps did the most to change attitudes about wetlands over the past three decades (81). The introduction to the inventory stated: "So long as this belief prevails (that wedands are wastelands), wetlands will continue to be drained, filled, diked, impounded, or otherwise altered, and thus will lose their identity as wetlands and their value as wildlife habitat. " The inventory created the lasting perception that wetlands rapid- ly were disappearing — a perception that galvanized certain groups to preserve wetlands. Since the intrinsic values — recreation and a sense of the need to preserve the unique flora and fauna of scenic, natural areas — that motivated wetland protection at the outset were not appreciated uni- versally, proponents began to investigate more tan- gible, ecological services provided by wedands. Ini- tially, these other services were suggested in the FWS wetland inventory report: . . . the storage of ground water, the retention of surface water for farm uses, the stabilization of run- off, the reduction or prevention of erosion, the pro- duction of timber, the creation of firebreaks, the provision of an outdoor laboratory for students and scientists, and the production of cash crops, such as minnows (for bait), marsh hay, wild rice, black- berries, cranberries and peat moss (81). In his 1977 environmental message, President Carter conveyed an attitude about wetlands that stood in sharp contrast to the attitude of the early 1900's: The Nation's coastal and inland wetlands are vi- tal natural resources of critical importance to the people of this country. Wetlands are areas of great natural productivity, hydrological utility, and en- vironmental diversity, providing natural flood con- trol, improved water quality, recharge of aquifers, flow stabilization of streams and rivers, and habitat for fish and wildlife resources. Wedands contribute to the production of agricultural products and tim- ber and provide recreational, scientific, and esthetic resources of national interest.' Knowledge of the importance of the ecological services provided by wetlands has increased steadi- ly, especially over the past two decades. As wedands research continues, knowledge about the values of individual and different types of wetlands will, in all likelihood, improve. For example, some wedand services, such as ground water recharge, have been found to be less significant than once thought. On the other hand, the ecological services of inland freshwater wetlands with the exception of wildlife habitat are not widely recognized by the general public. It is quite possible that some wetlands may provide ecological services that are as yet unknown or poorly documented. In addition, the overall sig- nificance of continuing, incremental losses of wet- lands is well known only in a few cases. Waterfowl managers, for example, use the number of prairie potholes in the Midwest to predict fall duck popula- tions; without these wetlands. North American duck populations would decrease by about half. On the other hand, the importance of wedand-derived detritus for estuarine fish and shellfish populations relative to other sources of food, such as algae and detritus from upland areas, is not well known. Fu- ture research may resolve many of these uncertain- ties. 'Statement by the President accompanying E.xecutive Order 1 1990; 42 FR 26961 (1977). Ch. 3— Wetland Values and the Importance of Wetlands to Man • 39 INTRINSIC VALUES OF WETLANDS In recent years, the case for preserving wetlands has been based more and more on the ecological services provided by wetlands^ and on the avail- ability of scientific evidence documenting these ser- vices. For example, in a recent paper, William Reil- ly stated: Every bit of evidence that does exist suggests that our interior wetlands are vital elements of national estate. But there are many challenging voices — questioning voices. These will become stronger in future years. They will demand to be shown the scientific evidence behind wetland conservation decisions (81). This situation perhaps has obscured one funda- mental motivation of some for preserving wet- lands — the desire to preserve, intact and unspoiled, unique natural ecosystems. For many personal rea- sons, whether ethical, religious, esthetic, or recrea- tional in nature, people value wedands for their in- trinsic qualities. Because these intrinsic values are intangible and thus difficult to express in quanti- tative and economic terms, they are often over- looked in a society where decisions are based on numerical cost-benefit analyses. Although there have been attempts to quantify these values, this discussion simply identifies those characteristics of wetlands that people value. Wetlands as Natural Areas Some people are attracted to an environment that essentially is untouched by man's presence,^ which is an attraction akin to the lure of wilderness. One scientist, for instance, writes in the preface to a wet- land study: The river swamps are, for many of us in the Southeast, the last wilderness. True, they are nar- row, even the mighty Altamaha swamp scarcely ex- ^Massachusetts, for instance, the first State to enact a wetland law, recognizes seven wetland values: flood control, prevention of pollu- tion, prevention of storm damage, protection of the public and private drinking water supply, protection of ground water supply, protection of fisheries 1978-79; Act of Mar. 25, 1965; ch. 220, 1965; Massachusetts Acts 116; Act of May 22, 1963; ch. 426, 1963; Massachusetts Acts 240. 'In the following discussion, examples illustrating these character- istics of wetlands are presented. Unless otherwise noted, these exam- ples are taken fromj. Perry andj. G- Perry, Guide to Nawraj Areas of the Eastern United States (New York: Random House Publishers). ceeds 5 miles in width; yet in length they are large indeed, often stretching more than half the length of the state. Narrow as they are, many provide a true wilderness experience. Where else in this mechanized, modern world can we so quickly lose ourselves in wildness without evidence of the mas- sive civUization that surrounds us? (97). Part of the reason that marshes, swamps, bogs, and other wetlands are associated with natural, un- disturbed environments is that they are often the last areas to be developed. The difficulty and ex- pense of draining wetlands for development have encouraged people to develop other areas first. Various studies have found that wetlands rank high in esthetic quality in comparison to other land- scape types (82). One particular value of wetlands is the attraction of the land-water interface. Many people find the edge between land and sea, lake, or stream scenically appealing, and such areas often include wetlands as well as beaches and banks. Small wetlands are capable of being surveyed in a glance or traversed in a few minutes and offer a contrast to the adjoining land or water. Seen from a passing car or hiking trail, wetland edges buffer commercially or agriculturally developed lands, providing scenic variety. Small wetlands also con- trast with other types of natural areas, such as upland forests or open water. Large wetlands have a similar "variety" value along their edges but may have other esthetic at- tributes as well. Of all natural areas, the most mys- terious and haunting in appearance are the large cypress swamps draped with Spanish moss. Less exotic are wooded swamps, which are full of dif- ferent shapes, textures, plants, and animals. Ac- cess and visibility are important factors; for exam- ple, pleasing wooded swamps should not be choked with underbrush that greatly impedes passage by foot or canoe. A large, open, grassy marsh can pre- sent quite an esthetic contrast and a feeling of open space. In addition to the esthetic qualities of wetlands themselves, wetland flora and fauna lend a special esthetic attraction to wetlands. Waterbirds are a good example: herons, egrets, storks, terns, peli- cans, and cranes all are found commonly or pri- 40 * Wetlands: Their Use and Regulation Photo credit: U.S. Fist^ and Wildlife Service. C. Ker^neth Dodd. Jr. Draped with Spanish moss, the haunting Santee-Cooper River Swamp in South Carolina provides an uncommon wilderness experience Photo credit US Fish and Wildlife Service A number of distinctive and unusual plants grow In wetlands. Five genera of insectivorous plants, for instance, including this Venus fly trap, are found in North Carolina pocosins marily in wetland habitats. Other species are more unusual. Five genera of insectivorous plants can be found in a North Carolina pocosin, including round-leaved sundew, butterworts, Venus fly traps, bladderworts, and two species of pitcher plants. In addition, wetlands, particularly those whose origins were glacial, often provide habitat for "relict" plants and animals, that is, those that were once, but are no longer, endemic to an area. Cranesville Swamp in West Virginia has a number of relict spe- cies, including Tamarack, Swainson's, and hermit thrushes; Nashville and mourning warblers; and purple finch, that typically are found much farther north. Overall, wedands are characterized by many dif- ferent kinds of flora and fauna relative to other ecosystems. For example, approximately 5,000 spe- Ch. 3— Wetland Values and the Importance of Wetlands to Man • 41 cies of plants, 190 species of amphibians, and ap- proximately one-third of alJ bird species are thought to occur in wetlands across the United States (18, 22,45). A single, freshwater tidal marsh may have from 20 to 50 plant species. Over 100 woody plant species may inhabit bottom lands. (19). This diver- sity of plant types creates, in turn, a diversity of habitats for animals. Living in the Okefenokee Swamp in Georgia are over 200 species of birds, 41 species of mammals, 54 species of amphibians and reptiles, and all duck species found along the Atlantic flyway. In the Bombay Hook National Wildlife Refuge in Delaware, an area of 12,000 acres of brackish tidal marsh, over 300 bird species have been recorded. Tinicum Marsh, a national environmental education center outside of Phila- delphia, has more than 300 plant species and over 250 bird species. In addition to the many different kinds of flora and fauna, abundant populations of wildlife, espe- cially waterfowl and waterbirds, make wetlands even more attractive as natural areas. The Merrit Island National Wildlife Refuge in Florida, an area with over 34,000 acres of freshwater and saltwater marshes and swamps, has a wintering waterfowl population of nearly 70,000 ducks and 120,000 coots. Hundreds of thousands of robins arrive at the Okefenokee Swamp each year. Mass nestings of wood storks — as many as 6,000 pairs — occur at the Corkscrew Swamp Sanctuary in Florida. Wetlands for Recreation and Education Wetlands provide direct enjoyment to inhabi- tants, visitors, and passers-by in many ways. Rec- reational activities in or around wetlands, including hiking, boating, fishing, hunting, and the obser- vation of wildlife are pursued by millions of peo- ple and amount to billions of dollars in expendi- tures each year. For example, 19 of the 25 most visited National Wildlife Refuges (out of 309 refuge Pholo credit: US Fish ana '.Vildlife service. Lawrence S- Smith A Youth Conservation Corps group is instructed In marsh ecology at a National Wildlife Refuge. Environmental education is a major theme in many parks and public areas established around vi/etland areas 42 • Wetlands: Their Use and Regulation units) have substantial wetland components (90). These 19 refuges represent approximately 50 per- cent of the total visitation to all U.S. National Wildlife Refuge units. Several of these refuges are predominantly wetland environments: J. N. Ding Darling Refuge in Florida, considered one of the best birdwatching sites in the United States, had 671,000 visitors in 1981 (8th overall); Loxahatchee Refuge in Florida had 333,329 visitors (19th); Oke- fenokee Refuge, one of the oldest, largest, and wild- est swamps in the United States, had 257,927 visit- ors (21st); the Great Swamp Refuge, more than half of which is wilderness within the New York City Metropolitan Area, had 250,756 visitors (23d). Recreational use of the Everglades National Park in Florida averaged 675,000 from 1979 to 1981 (60). Wetlands also may provide learning opportuni- ties for the general public or sites for educational and scientific purposes. Research on such subjects as botany, ornithology, and anthropology frequent- ly is carried out in wetland areas. Environmental education is a major theme in many parks and pub- lic areas established around wetlands. For exam- ple, the environmental center at Tinicum Marsh on the outskirts of Philadelphia coordinates numer- ous public education programs. In 1981 it had 32,730 visitors (60). From a purely scientific standpoint, the concept of the ecosystem has played an important role in environmental research and in the formal teaching of ecology. Because of the importance of water to the biosphere, most ecosystem study areas are se- lected to include water bodies such as streams, lakes, and wetlands. Wharton, (97) for instance, describes the scientific opportunities available through the Alcovy River Swamp: The Alcovy River is ideally suited for educational uses: it is essentially unpolluted, it is located within easy driving distance of a large metropolitan area but is unaffected by it; and it contains a unique swamp ecosystem found nowhere else in the Geor- gia Piedmont. The river swamp has a diversity of habitats and a corresponding diversity of plants and animals. It offers aquatic communities of all types of water, both flowing and still. The periodically high bio- mass of certain plant and animal groups offers an approach to community ecology and productivity. The drying up of bodies of water imitates both Pa- leozoic and monsoonal climatic effects on life and can illustrate the evolutionary transition from water to land. The swamp shows rapid changes in physio- chemical conditions. The yearly import of decomposed mineral mat- ter can involve both geological and cultural (agri- cultural) concepts. The processes of photosynthesis and decomposition can be readily demonstrated. Both the aquatic and the terrestrial segments of this ecosystem are subject to an annual series of plant and animal communities (succession), rapidly en- forced by the regimen of the hydrocycle. Inverte- brates such as clams, snails, leeches, adult aquatic insects, and larvae of aerial forms are extremely abundant — some of the species are "indicators" of the degree of pollution present. Much of the swamp fauna (invertebrates, fish, salamanders, mammals, birds) are present in mid- winter, when other habitats are barren. Many of the vertebrate groups are yearly renewable by in- undation (fish), are fossorial (salmanders), or are extremely plentiful (frogs). Thus, the animal com- munity is not easily damaged or overcollected. There are few subsurface runways to crush, or delicate layers of litter and humus to compress, as in a terrestrial forest. Most of the mammals are renewable by migration from the river corridor if accidentally killed; the tracks, droppings, or other evidence of most are readily observable on the bare swamp floor (raccoon, otter, mink, wildcat, beaver, rodents, shrews). The ecosystem is adjusted to what might be called "annual catastrophism." Even the forest floor is changed and renewed to some extent annually. Other Intrinsic Values In addition to those values previously discussed, there may be other less obvious but just as impor- tant reasons for preserving natural areas, including wedands (28). Many plants and animals may have great potential resource value for food, chemicals, drugs, and so forth, but are as yet undiscovered or undeveloped. Some scientists believe that all species are an integral part of the natural environ- ment and contribute in some, perhaps unknown, way to its natural order and stability. The conserv- ative belief is that excessive manmade impact on this natural system could cause irreversible changes in the natural order of the environment that may Ch. 3— Wetland Values and the Importance of Wetlands to Man • 43 carry an unknown risk of serious damage to hu- mans and their civiHzation. Natural systems can provide baseHne conditions that help determine the extent to which the environment has been affected by man's activities and pollution. They may pro- vide models for restoring or replacing habitats that have been significantly affected or even models of long-term survival for redesigning gready modified, man-dominated systems that typically have not worked reliably over long periods of time. Many people believe that unaltered natural areas, including wetlands, are valuable in and of themselves, regardless of any tangible benefits or ecological services society may receive from them. The reassurance that wetlands and other types of natural areas exist for both present and future gen- erations can be a strong motivation to preserve wedands in an undisturbed state. The Nature Con- servancy, an organization whose goal is "the pres- ervation of natural diversity by protecting lands containing the best examples of all components of the natural world," has devoted 50 percent of its past preservation efforts to the protection of wet- lands. In the future, it plans to expand this to ap- proximately 75 percent (53). Similarly, the North Carolina Natural Heritage Program gives top pri- ority to protection of Carolina bays (bog swamps), bottom land swamps, and peat bogs (80). Under the South Carolina Heritage Trust Program, 60 percent of the areas preserved are shallow impound- ments, marshes, flood plains, and wetland depres- sions (80). In the Wisconsin Scientific Areas Pro- gram, which inventories unique natural areas, ap- proximately 50 percent of all inventoried areas are wetlands (36). ECOLOGICAL SERVICES OR RESOURCE VALUES OF WETLANDS The interaction between the hydrologic regime and the wetland topography, saturated soil, and emergent vegetation largely controls the general characteristics and the significance of the processes that occur in wetlands. The processes are in turn responsible for the ecological services the wetland may perform (fig. 4). Isolated wetlands may temporarily store runoff, and flood plain wetlands may provide additional conveyance capacity for flood waters, thereby re- ducing floodpeaks in downstream areas. During pe- riods of inundation, water flows over and through the wetland, depositing nutrient-rich organic and inorganic material suspended in the water. This suspended material is "trapped" along with any toxic materials that may be bound onto this sus- pended material. The nutrients and their substances thus become involved in many complex biochemical cycles within the wetland system. These nutrients help fuel the relatively high plant productivity characteristic of most wetlands during the growing season. The leaves of plants provide food and hab- itat for many forms of wildlife and endangered spe- cies during the growing season. At the end of the growing season, when the vegetation dies back, some of the leaf material remains in the wetland to support future plant growth in the coming sea- son. Other leaf material is flushed into adjacent water bodies where it provides a nutrient-rich source of food for many aquatic organisms in the food chain. The plant roots anchor the wetland soils and prevent their erosion in some flood plain and coastal environiaents. The ecological services of wetlands are described in more detail below.* Floodpeak Reduction The ability of wetlands to store and convey flood- water is primarily a function of their topography. Many isolated freshwater and river wetlands are ^Recent reviews of the scientific literature have been completed by: 1) P. R. Adamus and L. T. Stockwell, "A Method tor Wetland Func- tional Assessment," U.S. Department of Transportation, Federal Highway Administration, Office of Research, Environmental Divi- sion, Washington, D.C., 1983, p. 176; and 2) J. H. Sather and R. P. Smith, "An Overview of Major Wetland Functions," U.S. Fish and Wildlife Service, Washington, D.C.. 1983. 44 • Wetlands: Their Use and Regulation Figure 4.— Relationship Between Wetland Processes and Values Periodic inundation Wetland processes Ecological services C^^ Food and habitat !_[]> Food chain support I ^ Floodpeak reduction C^^Groundwater recharge t~~^\Na\p.r quality improvement r~^ Shoreline erosion control SOURCE: Office of Technology Assessment topographic depressions that retain runoff flowing into them, at least until they are full. Also, during flooding, the river overflows its banks and spreads laterally across the flood plain , increasing its cross- sectional area and conveyance capacity. By tem- porarily storing storm water and providing capacity to convey floodwaters, wetlands can reduce flood- peaks and the frequency of flooding in downstream areas. Vegetation in flood plain wetlands further reduces the flow velocity of the river, thereby reduc- ing potential floodpeaks in downstream areas and riverbank erosion. If the soil in a wetland is un- saturated, the soil itself will provide some storage capacity during periods of flooding. While the value of some wetlands for flood storage and conveyance is well known, analytical techniques for predicting the magnitude of this service still are being devel- oped. The value of inland wedands to reduce flood- ing in downstream areas generally depends on the area of the wetland, its location downstream, the magnitude of flooding, and the degree of encroach- ment on the wetland (16,31,67,88). Inflow-Outflow Measurements Only two studies were found that actually deter- mined the storage capacity of a wedand during flood conditions. One study measured water levels of a cypress-tupelo swamp adjacent to the Cache River in southern Illinois before and after flooding to cal- culate the amount of flood water storage. The 90- acre swamp, which is separated from the river by Ch. 3— Wetland Values and the Importance of Wetlands to Man • 45 a natural levee, stored 80,131 cubic meters (m') of water. If this amount of storage were extrapolated to the entire area of swampland in the watershed, total wetland storage would equal 8.4 percent of the total flood runoff as measured at a downstream gage (52). Bernot found that flow was about 5,000 cubic feet per second (ft'/s) into the Thief Run Wildlife Management Area and the Agassiz National Wild- life Refuge, while outflow was approximately 1,400 ft^/s. He calculated that the flood storage capacity and losses due to the other factors of these two wet- land areas reduced the floodpeak at Grand Forks, by about 0.5 foot and at Crookston by about 1.5 feet (8). Comparison of Floodpeaks From Wetland and Nonwetland Watersheds By studying floodpeaks in 15 watersheds, No- vitzki found that floodpeaks may be as much as 80 percent lower in watersheds with large lake and wetland areas than in similar basins with little or none. Watersheds with 40-percent lake and wedand area have floodpeaks only 20 percent as large as those with little or no wetland area. While flood- peaks were found to be lower in watersheds with a large percentage of wetlands, total streamflow in the spring was higher in basins with large lake and wetland areas (63). Analysis of Flood Hydrographs Flood hydrographs — graphs of the time distribu- tion of runoff from a drainage basin — of perched peat bogs and peadands indicate that these wedands temporarily store and slowly release storm waters (5,9). Long-term hydrographs from the Passaic River, N.J., and the Ipswich River, Mass., showed that the wetlands adjacent to the rivers play an im- portant role in delaying runoff (31). Synthetic hy- drographs (not calculated on historical data) for eight wetland areas also showed reductions in peak flows (94). Actual flood-storage capacity often will depend on environmental conditions prior to flooding or on the relationship of a particular wetland to the regional hydrology. For example, when evapo- transpiration rates are low and water is ponded in wetlands, runoff during periods of heavy precipita- tion may be greater from wetlands than from up- land areas (because the soil is saturated and the sur- face storage capacity quickly is exceeded) (51,77, 92). On the other hand, high rates of evapotran- spiration and low water tables favor storage of flood- waters. In some cases, wetlands provide no stor- age capacity for floodwaters. For example, a hy- drographic analysis of two Massachusetts swamps indicated that both wetlands contributed signifi- candy to floodpeaks because of their rapid discharge of ground water (64). The Role of Vegetation in Flooding There have been a few attempts to isolate the ef- fect of vegetation on flooding. The frictional drag on runoff flowing through wedand vegetation is rep- resented by a roughness coefficient called "Man- ning's 'n.' " The higher the value of "n," the greater the drag and the slower the flow velocity of floodwaters. Values of "n" vary widely and are highly dependent on the type and amount of vege- tative cover. In general, the value of "n" for a river wetlands in or adjacent to it can be approximately twice the value of channels without associated wet- lands (15). Impact of Wetland Filling and Development on Flooding The Corps has used model-generated hydro- graphs to estimate the volume of storm water that could be stored in the basin wetlands of the Charles River, Mass., and to determine the reduction in storage, assuming future encroachment (89). Fol- lowing a storm in 1955, approximately 50,000 acre- ft of storm water flushed past the Charles River Village gaging station with a peak flow of 3,220 ft^/s. This amount is equivalent to 5 inches of runoff from the 184-square-mile drainage basin. On the adjacent Blackstone River, which has few, if any, wedands, the storm discharge peaked at 16,900 ft'/s and the bulk of the storm water was discharged in a much shorter time period than on the Charles. Based on this analysis, it was predicted that a 40- percent reduction in wetland area along the river would result in a 2- to 4-foot increase in floodpeaks and would increase flood damages by at least $3 million annually. Hydrographs of the Neponset River Basin, Mass., were used to determine the impact of en- 46 • Wetlands: Their Use and Regulation croaching on the basin's flood plains and wetlands (1). The study predicted that the basinwide flood level for the 100-year flood would increase 0.5 feet if 10 percent of the flood plain/wetland storage capacity were lost, and 3 feet if 50 percent of the flood plain/wetland storage capacity were lost. Fill- ing a wetland will reduce its storage capacity; if the fill material rises above the level of the flood plain, flood conveyance value also may be reduced. The effects of drainage on floodflows are slightly more complicated. One point of view is that drain- age increases floodpeaks by synchronizing and speeding the runoff of water and by eliminating the potential storage of runoff in wetlands. A contrast- ing viewpoint is that drainage channels may reduce floodpeaks by draining away heavy rains that other- wise would have left the soil saturated through the winter, reducing the storage available during critical spring rain and snowmelt. Research to date has not yet resolved this controversy.^ Shoreline Erosion Control Shoreline erosion is a natural process caused by river currents during flooding, tidal currents in the coastal areas, and wind-generated waves along the shores of large lakes, broad estuaries, and ocean- facing barrier islands. Boat wakes also can cause considerable shoreline damage. Four characteristics of vegetated wetlands are responsible for reducing erosion: 1) the low-gradient shore that absorbs and dissipates wave energy (70); 2) the dampening and absorption of wave energy by the plants themselves (44,95); 3) the root struc- ture and peat development in wetlands that bind and sfabilize the shore (71,76); and 4) the deposi- tion of suspended sediment that is encouraged by dense growth of wetland plants.'' 'See the following references for reviews of information pertaining to the impacts of wetlands draining on flooding: 1) L. J. Brunn, J. L. Richardson, J. W. Enz, and J. K. Larsen, "Slreamflow Changes in the Southern Red River Valley of North Dakota," North Dakota Farm Research Bimonthly Bulletin, vol. 38, No. 5, 1981, pp. 11-14; 2) John M. Malcolm, "The Relationship of Wedand Drainage to Flooding and Water Quality Problems and Its Impact on the J. Clark Salyer National Wildlife Refuge," FWS, Upham, N. Dak., 1979; and 3) J. E. Miller and D. L. Frink, "Changes in Flood Response of the Red River of the North Basin, North Dakota-Minnesota," U.S. Geo- logical Survey, Open File Report 82-774, 1982. 'Recent reviews of the scientific literature have been completed by P. R. Adamus and L. T. Stockwell, "A Method for Wetland Func- Vegetated freshwater or saltwater wetlands lo- cated adjacent to open but usually sheltered bodies of water significantly reduce shoreline erosion caused by large waves generated by occasional storms and boat traffic' Wetlands adjacent to rivers also may reduce riverbank erosion from strong cur- rents during major flooding. Although it general- ly is agreed that wetland vegetation does not nat- urally establish itself in high-energy environments where the potential for erosion is greatest, wetland plants, once established, do help to control erosion, stabilize the soil, encourage deposition of sediments, and dampen wave energy. Isolated wetlands not associated with larger bodies of water will not have significant value for erosion control. Potential Economic Importance Shoreline erosion is a major problem in many coastal areas. In Virginia, for instance, it has been estimated that 1,476 hectares of tidal shoreline eroded away between 1850 and 1950. This amount represents approximately 20 percent of the 5 million metric tons of sUt and clay that wash into Virginia's estuaries annually (39). The impacts of shoreline erosion include: loss of public and private proper- ty and the subsequent loss of taxable income for localities, filling of navigable waters with eroded sediment, increased turbidity of waters, siltation offish and wildlife habitat, and loss of recreationally valuable sand beaches. Millions of dollars are spent each year to reduce shoreline erosion and main- tain the navigability of channels. Ability of Wetlands to Control Shoreline Erosion Wetlands not only resist erosion themselves, but also protect the more easily eroded upland areas shoreward of the wetland. Three studies have com- tional Assessment," U.S. Department of Transportation, Federal Highway Administration, Office of Research, Environmental Divi- sion, Washington, DC, 1983, p. 176. ^Most of the existing literature on this function has been reviewed in the following: 1) H. H. Allen, "Role of Wetland Plants in Erosion Control of Riparian Shorelines," Wetlands Functions and Values: The State of Our Understanding, P. E. Greeson, J. R. Clark, and J. E. Clark (eds.) (Minneapolis. Minn.: American Water Resources Association, 1979), pp. 403-414; 2) Carter, et al. (15); 3) R. G. Dean, "Effects of Vegetation on Shoreline Erosional Processes," Wetland Functions and Values: The State of Our Understanding, P. E. Greeson, J. R. Clark, and J. E. Clark (eds.) (Minneapolis, Minn.: American Water Resources Association, 1979), pp. 415-426; and 4) Institute for Water Resources (88). Ch. 3— Wetland Values and the Importance of Wetlands to Man • 47 pared the rate of erosion of uplands buffered by wetlands to that of unbuffered uplands. In a study of two similar sites on the Hacken- sack River in New Jersey, the marsh vegetation at one site was cut; at the other site, the marsh was left in its natural condition (26). Both sites were subjected to waves generated by heavy boat traf- fic. While the uncut site exhibited only a negligi- ble retreat of the bank over the year of monitor- ing, the bank at the second site retreated nearly 2 meters, with most of the change occurring imme- diately after the marsh was cut. In a second study, the rate of erosion of upland areas at three sites on the Chesapeake Bay over a 20-year period was measured with aerial photo- graphs. Wetlands eroded as fast as adjacent up- lands; however, erosion of uplands buffered by the wetlands was negligible (70). In a third study the retreat/ advance of the shore- lines of an artificially planted marsh (Juncus roe- merianus, Phragmkes australis, Typha latifolia, and Spartina alterniflora) and of an adjacent un- planted area were measured over a period of 8 years (7). Initial erosion of the planted area was followed by a period when the shoreline actively expanded before it appeared to reach equilibrium. In general, the volume of sediment eroded from the unplanted shore averaged 2.3 m^ per lineal meter-year (m'/ lineal m-yr.), nearly four times the average rate observed in the planted marsh. In addition, the un- planted shore retreated at a rate that was more than twice that observed for the marsh-fringed shore. Limitations of Wetlands to Control Erosion Natural wetlands are typically found in low-en- ergy environments, sheltered from extensive wave action (4,17). Artificial wetlands, however, often are constructed in higher wave-energy environments where natural wetlands would not typically occur. Young rooted plants are used rather than allow- ing the shoreline to seed itself naturally. In addi- tion, with many artificial plantings, a "toe" or low ridge is constructed below the marsh to contain the marsh soil and to reduce the impact of incoming waves until the plants are established firmly. Most of the literature citing the erosion-control functions of wedands is based on observations of marshes spe- cifically planted to control erosion. For example. in a 1981 survey of 86 marshes planted to control shoreline erosion in 12 coastal States, 33 plantings were found successful, 25 were partially successful, and 28 failed (43). Even planted marshes, however, were more frequently successful under less severe wave environments. Ground Water Recharge Ground water recharge is the ability of a wedand to supplement ground water through infiltration/ percolation of surface water to the saturated zone (88) . Some wetlands that are connected hydrolog- ically to a ground water system do recharge ground water supplies and assume an important local or regional role in maintaining ground water levels. However, owing to the low permeability of organic soils or the relatively impermeable layers of clay typically found in wedands, adjacent upland areas often have a greater potential to recharge ground water (16). In addition, wetlands may often serve as discharge rather than recharge areas. ^ Ground water recharge can occur in isolated (basin) wetlands, such as cypress swamps, prairie potholes, Midwestern and Northeastern glaciated wetlands, and flood plain wetlands. Cedarburg Bog, adjacent to Milwaukee, Wis., is an example of a high-value recharge area (58). Much of the precipitation falling on this basin percolates down- ward through the soil and enters openings in a dolo- mite aquifer. Since the bog occupies the basin of a former postglacial lake on a high point in the sur- rounding topography, the water percolates radial- ly away from the bog, influencing ground water supply over an area of 165 mi^. While some wetlands may recharge ground water, their recharge value relative to upland areas may be low. In three watersheds in Minnesota, for instance, the greatest amount of ground water re- charge was found to occur on upland sands, and the least in wetland peats (93). In addition, the quantity of water recharged may vary widely. For example, in one wetland studied only 39 gallons per day (gal/d), or 0.05 percent of the annual water budget, infiltrated the wetland (12). On the other hand, the average yearly natural recharge calcu- lated for Lawrence Swamp in Massachusetts was 'Adamus and Stockwell, op. cit. 48 • Wetlands: Their Use and Regulation 8 million gal/d (assuming 44 inches of precipita- tion/yr) (56). The quality of the ground water resource also determines the value of a particular recharge area. WhUe Lawrence Swamp recharges large quantities of water to the shallow aquifer direcdy underneath it, this aquifer has a high content of fine sands, iron, and manganese and cannot be used as a water sup- ply (56). Water Quality Improvement By temporarily retaining pollutants, such as sus- pended material, excess nutrients, toxic chemicals, and disease-causing micro-organisms, it is generally believed that wedands improve, to varying degrees, the quality of the water* that flows over and through them. Dissolved nutrients (i.e., nitrogen and phosphorous) may be taken up directly by plants during the growing season and by chemical absorption and precipitation at the wedand soil sur- face. Organic and inorganic suspended material also tends to setde out and is trapped in the wedand. Some pollutants associated with this trapped ma- terial may be converted by biochemical processes to less harmful forms; some may remain buried. Others may be taken up by the plants growing in the wedand and either recycled or transported from it. The accumulation of toxic chemicals, such as heavy metals and petroleum and chlorinated hydro- carbons by wetlands may be only temporary (from days to years). On the other hand, some toxic chemicals have accumulated in many wedands over a much longer time. With some toxic chemicals, like degradable pesticides, the fact that these pollutants are secured in the wetland long enough to degrade is important. Other toxics either remain buried or are taken up by the wetland plants. While wetlands may, under natural circum- stances, retain nutrients on a net annual basis, the value of a particular wetland for water quality im- provement depends on the effect of the nutrient storage on an adjacent or connected body of water. However, even if a wetland does not retain large amounts of nutrients on a net annual basis, it may influence the timing of nutrient inputs into adja- cent waters. By retaining nutrients during the grow- ing season, for instance, and exporting them after the growing season, wetlands may have a positive influence on water quality. Freshwater wetlands have been used successfully for secondary treatment of sewage effluents. Trapping Suspended Sediment Excessively high levels of suspended material in the water column can be detrimental. By increas- ing turbidity, suspended sediment can interfere with fishing, swimming, and the esthetic appeal of water. Reduction in light penetration due to increased tur- bidity can kill aquatic plants, and settling of the suspended sediment can smother bottom-dwelling invertebrates and impair fish spawning. If sus- pended sediment has a high organic content, the dissolved oxygen level in the water column may de- crease to levels that may adversely affect many or- ganisms. One of the major water quality functions of wet- lands is the removal of suspended sediment. By re- ducing wave energy and the velocity of water flow- ing through the wetland, wedand plants encourage the deposition of suspended sediment. In fact, sedi- mentation rates are related directly to the density of marsh vegetation (7). Measurements of sediment accretion, most of which are for marine or estuarine environments, range from 0.04 centimeters (cm) to 1,100 cm/yr.9 The ability of vegetated wetlands to trap sus- pended sediment more effectively than similar un- vegetated areas was shown clearly in an 8-year study on Currituck Sound in North Carolina. Dur- ing the first 5 years, planted marsh lost an average of 1 .4 m^/linear m of beach/yr, while an adjacent unplanted area lost 3.3 m'/yr. Between 1978 and 1979 the planted areas, however, captured an av- erage of 1 .5 m^ of sediment/yr; the unplanted area lost an additional 1.3 m'. From 1979 to 1980, the planted area gained 0.6 m' and the unplanted area lost 0.4 m'. During the last year of the study, the planted area appeared relatively stable, while the unplanted area lost 1.0 m' (7). *The term "water quality" is defined here as the chemical, physical, and biological condition of the water itself and not more broadly as the condition of the wetland and its associated habitat. 'Adamus and Stockwell, op. cit. Ch. 3— Wetland Values and the Importance of Wetlands to Man • 49 As the elevation of wetlands increases, accretion of sediment will slow. In one study, for instance, a Spartina marsh near the mean high-water level annually accreted from 2.0 to 4.25 millimeters (mm) of sediment. An area of colonizing Spartina at a lower elevation, however, accreted sediment at the rate of 9.5 to 37.0 mm/yr (10). Marshes tend to trap sediment as long as they are inundated by sediment-laden waters. Suspended organic and nonorganic material has a strong tendency to adsorb other pollutants, in- cluding nutrients, pathogens, and toxics, such as heavy metals and chlorinated and petroleum hydro- carbons, that then are deposited with the sediment in wetlands (10). The ability of wetlands to "trap" suspended material greatly influences the fate of pollutants associated with the suspended material and the potential ability of a particular wetland to improve water quality. Removing Toxic Substances Heavy metals, chlorinated and petroleum hydro- carbons, radionuclides, and other potentially harm- ful toxic substances may persist for many years. Because they tend to adsorb onto suspended ma- terial, toxics can be trapped in wedands, either tem- porarily or permanently. At the sediment surface, these metals remain immobilized. Once buried and exposed to the anaerobic conditions that typically prevail in sediment, metals again can become mo- bile; however, they will be trapped within the sedi- ment by the oxygenated zone at the sediment sur- face (54,55). Heavy-metal-removal efficiencies of wetlands vary from 20 to 100 percent, depending on the metals involved and the physical and bio- logical variations that exist in wedand habitats (85). For compounds such as heptachlor, lindane, or enderin, which degrade readily in soils, the trap- ping of the sediment results in a very efficient and permanent process for removing these contami- nants from the water. (Natural or manmade altera- tions of the wetland caused by lowering the water table, dredging, and the like, however, could mo- bilize large quantities of toxic materials.) However, in general, it is not known yet to what extent wet- lands processes are capable of removing toxic ma- teriads over the long term. Some toxics may be tciken up from the sediment by wetland plants and transferred through the food chain to higher trophic levels when the plant ma- terial is consumed, either directly by herbivores or as detritus. Food chain transfer will depend on the toxic chemical and its form as well as the charac- teristics of the plant species and the chemical's loca- tion in the plant. For example, food chain transfer is known to occur with some metals, such as mer- cury or cadmium, but may not occur with others, such as lead. Synthetic materials, including chlor- inated hydrocarbons, are taken up by wetland plants, but food chain effects are not known. There probably is some selectivity of uptake of toxics by particular wetland plant species, but the available data are insufficient to indicate any universal trends. In summary, though wedands may remove toxics from water, it is possible that such removal of heavy metals eventually may lead to contamina- tion of higher trophic levels by passage up the food chain (42). Influencing Nitrogen and Phosphorus Nitrogen and phosphorus are two nutrients that are necessary for the growth of algae. In excess, however, they can cause "blooms" of algal growth that can impart an unpleasant taste to drinking water and can interfere with recreational uses of water. In addition, the decomposition of algae can reduce levels of dissolved oxygen in the water col- umn to levels that may be harmful to other orga- nisms that need oxygen for survival. Nutrients are retained in wetland by similar mechanisms as other pollutants (85). Both nitrogen and phosphorus readily adsorb to sediment and thereby tend to become trapped in the anaerobic sediment of wetlands. As with other toxics, how- ever, nutrients are not necessarily permanently trapped; they may, for instance, be rapidly assim- ilated by rooted wetland plants. In fact, the bulk of the nitrogen and phosphorus for plant growth apparently comes from the sediment. At the end of the growing season, much of the assimilated nu- trients may be leached from the plants. Boyd, for instance found that about 50 percent of the phos- phorus in dead cattail tissue was leached over a 50 • Wetlands: Their Use and Regulation 20-day period.* Another fraction of the nutrients in the plant is exported from the wetland as detritus; this fraction is probably highly variable, depending largely on the hydrology of the wetland. The dead plant tissue remaining in the wedand is rapidly col- onized by bacteria and the byproducts of the de- composition process, including inorganic nutrients, are released into the water column. Nitrogen stored in the plant, for example, is converted by these de- composers to ammonia. Plant material remaining in the wedand is eventually reincorporated into the sediment. It has been hypothesized that a signifi- cant amount of the nitrogen and phosphorus avail- able from the sediment for plant uptake is recycled from the plant growth of the previous year (42). Water Quality Considerations Aggregate Effect. — Present understanding of the processes described above is not sophisticated enough to predict their aggregate effect on water quality. Nitrogen fixation, for instance, the opposite process of denitrification (atmospheric nitrogen is fixed by certain bacteria and algae), can contribute significant amounts of nitrogen to the wetland ni- trogen budget and therefore cancel the effects of denitrification. Some wetland studies have measured the quantity of all pollutants entering the wetland from all sources — ground water, surface water, precipitation, and so forth — and the amount leaving the wetland. The aggregate effect of all wetland processes on water quality is reflected by the difference between the amount of pollutant entering and leaving the wetland. In this manner, it can be determined whether wetlands act as a sink or a source of pollutants. Thirty-nine input-output studies, focusing for the most part on nitrogen and phosphorus, were re- viewed. These studies were screened carefully to meet a number of stringent criteria. First, since the behavior of the wetland varies greatly during dif- *The fate of nitrogen is more complicated than that of other pol- lutants thus far discussed. Nitrogen occurs in several forms in natural water; nitrite, nitrate ammonia, and organic nitrogen (proteins and other large molecules). In addition, the air contains over 78 percent nitrogen gas, which is exchanged continuously through the surface waters. Relatively large populations of micro-organisms in wetlands, under the right circurnstances, can convert nitrogen from one form to another. Thus, nitrogen can be removed ultimately from water by microbial conversion to gas through the process of denitrification, or conversely, fixed from the atmosphere and converted to inorganic ni- trogen. ferent seasons, only those studies sampling month- ly for at least a year were selected. Second, all chem- ical forms of nitrogen and phosphorus had to be measured: measurement of both organic and in- organic forms is necessary since the various forms are interconvertible. For nitrogen, total nitrogen (Kjeldahl) must have been measured in unfiltered samples and in nitrate and nitrite. For phosphorus, measurement of total phosphorus from unfiltered samples was required. Third, for studies of undis- turbed wetlands, all reasonable input and output sources had to be measured, including intermittent or temporary sources of surface runoff, ground water, and precipitation. In the case of an artificial pollution source, such as a sewage outfall, the failure to measure natural sources of nutrients was overlooked on the assumption that such sources were comparatively trivial. Measurement of all sig- nificant sources and sinks of water, however, was required, even if the quantity of naturally occur- ring nutrients was overlooked. Freshwater Systems. — Of 30 freshwater input- output studies reviewed, only seven (12,23,27,52, 62,98,99), met all the criteria listed above. A ma- jor drawback of these studies is that large quan- tities of pollutants doubtlessly flow into and out of wetlands during storms or floods. The chance of getting a good sample of nutrients flowing into a wetland during a major flood is small if outflow is sampled only monthly. One study (52), for in- stance, found that 99 percent of the nutrient flow into a flood plain swamp occurred during a single flood. The swamp floods approximately once every 1.13 years. Although Crisp (23) found a net export of nitro- gen and phosphorus in an eroding British peadand, all other authors found net reductions of nutrients in freshwater wetlands. Large percentage reduc- tions generally were observed where sewage was applied (12,27,98) and small percentage reductions were observed where nutrient sources were natural (52,62). One study (99) was unusual in that sewage and natural water were applied to artificially enclos- ed marsh plants so that surface outflow was pre- vented. Water that had filtered through the marsh sediments was sampled in outside wells. Since the natural hydrology of the marshes had been altered, the large percentage reductions in both the natural and sewage-treated marshes may not be represent- ative of activity of natural marshes. Ch. 3— Wetland Values and the Importance of Wetlands to Man • 51 Estuarine Systems. — Input-output studies are more difficult to conduct in estuarine or marine en- vironments owing to tidal fluctuations. Nine estua- rine studies were screened using the same criteria used for the freshwater studies. Findings from a single acceptable study (91) are reported in table 4. These results suggest that nitrogen was exported from a Massachusetts salt marsh. Evaluating Wetlands for Water Quality. — To evaluate the value of a wetland for improving water quality, a number of factors must be con- sidered. First is the condition of water in the water body adjacent to the wetlands. In many lakes, estuaries, and rivers, excessive nutrient concentra- tions cause undesirable algal blooms. In other bodies of water, however, desirable levels of primary productivity may be limited by a lack of these nutrients. If these waters have phytoplankton- based food chains, low nutrient concentrations can result in low productivity at all levels of the food chain. In this case, nutrients would be considered beneficial and not pollutants. The reduction of excess nutrients necessary to bring about an improvement in water quality is another consideration. For instance, an evaluation of a proposal to reconstruct wedands along the Kis- simmee River in Florida and thereby reduce nutri- ent loadings to Lake Okeechobee, concluded that a 50-percent reduction in phosphorous loadings would improve water quality, but a 10-percent re- duction would have little effect (41). In another study, lake-edge wetlands in Wisconsin did retain nitrogen and phosphorus; however, the levels of nu- trients flowing out of the wetland still were high enough to cause excessive algal growth (47). The timing of nutrient inputs and outputs also is important. A study of phosphorus inputs and out- puts from a forested riverine wetland in Illinois found that while the swamp took in 1 1 times more phosphorus than was discharged, nearly all of it was retained during flood periods (52). Disease-Causing Micro-Organisms Viruses and bacteria from sewage effluent or run- off from pastureland may contaminate drinking wa- ter, recreational water, and commercial fisheries. Because these micro-organisms are adsorbed onto particles suspended in the water column, they may be trapped along with the suspended material by wetlands. Pathogens can remain for many months in the soil matrix where they may be exposed to ultraviolet radiation or attacked by chemicals and other organisms, or they may naturally die off. Table 4.— Summary of Input-Output Studies Artificial/ Reference Wetland type Location natural Crisp (1966) Peat bog Britain N tvlitsch, et al. (1977) Flood plain Illinois N swamp Boyt, et al. (1977) Riverine Florida A swannp Dierberg and Brezonik (1978) . . Cypress Florida A swamp Novitzki (1978) Fresh marsfi Wisconsin N Yonika and Lowry (1979) Fresh marsh Massa- A shrub swamp chusetts Zoltek and Bayley (1979) Fresh marsh Florida A/N Valiela, et al. (1975) Salt marsh Massa- N chusetts Including ground water dilution calculated by chloride budget. SOURCE: References cited in column 1. Sampling frequency/duration Pollutant Input Output (kg/ha/yr) Percent change Weekly/1 year 745 38-57 4,864 71 + 552 ■^ 25 - - 87 Monthly and bimonthly 8,127 7,694 Monthly/1 year 90.0 11.5 -87 Monthly/2 years 144 113 12 -91 -96 Monthly (stream, wells); N 233 183 -21 periodically (runoff)/3 years P 5.0 4.6 -8 Sediment 3,909 735 -81 Monthly and bimonthly/ 1 year 4,782 859 1,817 205 -62 -76 Monthly/2 years 3,565 2,284^ -36 P(art.) 4,575 343^ -93 N(an.) 645 315^ -51 P(nat.) 46 16^ -65 Monthly/1 year N(nat.) 26,252 31,604 + 20 52 * Wetlands: Their Use and Regulation There is little published information on the fate of pathogens in wetland systems (3). Fish and Wildlife Values Wetlands are important to many species of fish and wildlife for food, habitat, and support of the food chain. The importance of plant productivity is reflected in the relatively high carrying capacity of wetlands for certain species. Bottom land hard- wood forests, for instance, have been found to sup- port nearly twice as many whitetail deer per unit area as do upland forests, owing, it is thought, to the abundance of food. Wetland vegetation also provides nesting material and sites for numerous birds and mammals; some freshwater fish rely on clumps of vegetation for depositing their eggs. Finally, emergent wetland plants provide the cover necessary for protection from predators or for stalk- ing prey for species of birds as well as fish and shellfish. Some species spend their entire life within a particular wetland; others are residents only dur- ing a particular lifecycle or time of year. Because of their value for food and habitat, wet- lands often become a focal point for varied wildlife populations within a particular region. The impor- tance of wetlands is reflected by the relatively large proportion of wetland in the National Wildlife Re- fuge System. While only 5 percent of the Nation's area (excluding Alaska) is wetland, nearly 40 per- cent of the area protected under the refuge system is wetland. In turn, these areas attract hunters, birdwatchers, and many other wildlife enthusiasts. Of the top 25 wildlife refuges most visited, 19 have a significant wetland component. Refuges contain- ing wetlands attracted nearly 14 million visitors in 1981 , approximately 50 percent of the number visit- ing all of the national wildlife refuges (90). Because of their numbers, it is impossible to de- scribe adequately all the different species that use wetlands. This section focuses on recreational and commercial species of prime importance to man and on endangered species that depend to varying de- grees on the food and habitat found uniquely in wetlands. Some species, termed "wetland special- ists," are heavily dependent on wetlands. They in- clude migratory waterfowl, mammals, the alligator, freshwater game fish, crayfish, and 35 endangered species. Because of the direct link between wetlands and these species, wetland losses will cause signifi- cant and adverse impacts on these indigenous pop- ulations. This section also identifies other wildlife that heavily use wetlands as well as other nonwetland areas. Deer, for instance, browse in bottom land hardwoods, but they are not limited to these areas. Wetland resources may, however, be a critical or limiting factor in their survival. Because these animals are not linked as strongly to wetlands as are wetland specialists, wetland losses would ad- versely affect populations of nonspecialists to a lesser extent. Finally, this section discusses the food chain val- ues of wetlands. Many commercially and recrea- tionally important species that do not directly use wetlands for feeding, nesting, or protection may feed on animals lower in the food chain that do rely directly either on wetlands or on detritus that floats from the wedand into adjacent bodies of water. The most important example of this food chain effect in terms of commercial and recreational value is the link between coastal wetlands and estuarine- dependent fish. Food and Habitat Migratory Waterfowl. — Wetlands are vital to many species of the duck, geese, and swan family of North America for nesting, food, and cover. These birds primarily nest in Northern freshwater wedands in the spring and summer, but use wet- lands for feeding and cover in all parts of the coun- try during migration and overwintering. The sur- vival, return, and successful breeding of many species, therefore, depend on a wide variety of wet- land types distributed over a large geographic area of the country (fig. 5). The major migratory routes, breeding and nesting areas, and overwintering areas roughly correspond with regions of greatest wetland concentration (see fig. 1). The most important areas for ducks and geese are the breeding areas of the North, like the prairie- pothole region, Canada, and Alaska. For over- wintering, the Chesapeake Bay, the gulf coast, the central valley of California, and the Mississippi River stand out (fig. 5). Also essentiad, but not in- Ch. 3— Wetland Values and the Importance of Wetlands to Man • 53 Figure 5.— General Pattern of Duck Distribution in North America SOURCE: M. Wellef, Freshwater Marshes: Ecology and Wildlife Managemenf (Minneapolis, Minn.: University of Minnesota Press, 1981). dicated on figure 5, are coastal saltwater and fresh- water tidal marshes, inland freshwater marshes, and bottom land hardwoods that are used as overwinter- ing and stopover areas by migratory waterfowl dur- ing their biannual migrations (33). Shrub swamps are used only to a limited extent by waterfowl, and bogs and mangroves are used only sparsely (81). While diets vary with any species and locality, depending on food preferences, availability, and the time of year, wedand vegetation generally com- prises a significant component of the diet of ducks, geese, and swans. A major distinction between feed- ing habits can be drawn between "dabbling," or surface, ducks and "diving" ducks, or pochards. 54 • Wetlands: Their Use and Regulation The mallard, for instance, the most commonly hunted waterfowl in the United States, is a dab- bling duck and feeds on plants and food just under the surface of the water. Bulrush, smartweed, and wildrice are the emergent wedand plants, and pond- weed and wild celer)' are submerged plants favored by the mallard. In contrast, the canvasback, a div- ing duck, typically feeds in deeper water. They pre- fer submerged plants, such as pondweed, wild cel- ery, and widgeon grass to emergent vegetation but still may feed on emergents when preferred foods are not available. Geese and swans, on the other hand, favor emergent wetland vegetation to sub- merged plants. Canadian and snow geese, in par- ticular, feed on the rootstocks of salt marsh cord- grass as well as on cultivated crops (81). Waterfowl also depend on wetlands for nesting sites. Inland freshwater and saltwater marshes and coastal tundra are the most important wedand types for waterfowl breeding (96). In general, waterfowl prefer wetlands where open water and vegetation are interspersed. Temporarily flooded wetlands have been known to have high breeding-pair densi- ties, probably because of plentiful invertebrates, which breeding waterfowl require for egg produc- tion (96). Northern freshwater tidal marshes are used to a more limited extent for breeding, and wooded swamps and bottom land hardwoods are used by wood ducks for nesting (66,78). Of the 44 species of waterfowl that use North American wetlands, 4 species of geese and 10 to 15 species of ducks are hunted in sizable numbers (6,59). In the 1980-81 season, for instance, 1.9 million people killed 12.9 million ducks and 1.7 million geese (13). FWS estimated that 50 percent of all hunters 16 years and older, or 5.3 million hunters, hunted migratory birds (includes non- waterfowl) in 1980, spending $638 million, or 11 percent of all hunting expenditures (32). In addi- tion, FWS estimated that of 100 million Americans 16 years and older who participated in outdoor ac- tivities related to fish and wildlife, 83.2 million par- ticipants spent $14.8 billion on observing and photographing fish and wildlife. Sixty-six percent of these participants were involved directly with observing or photographing waterfowl. Other Birds. — There are several other types of birds that are found commonly in wetlands (48). The American coot is physically and ecologically similar to the duck and is shot in considerable numbers. Coots have diets similar to those of ducks but build floating nests in emergent vegetation. Snipe also inhabit freshwater marshes and wet meadows and are strictly carnivores, feeding on aquatic invertebrates they puU from mud with their long bUls. The four rail species and the gallinules, which have special adaptations to wetlands, are commonly found there and are hunted to some ex- tent. Herons, egrets, cranes, storks, and ibises nest colonially in wetlands. Herons and egrets feed on fish, frog, and invertebrates in shallow marsh waters. Ibises and storks nest over water in pro- tected sites of deep marshes but feed in wet mead- ows and uplands. Mammals. — A number of mammals live in wet- lands. For example, muskrats may live in bank bur- rows or "houses" constructed of wetland vegeta- tion along the banks of freshwater and saltwater marshes, rivers, and streams.'" In freshwater their diets may consist of cattail, bulrushes, waterlilies, '"The following discussion is based on four sources of information: 1) Schamberger, et al. (80); 2) W. H. Burt and R. P. Grossenheider, A Field Guide to the Mammals, 3d ed. (Boston: Houghton-Mifflin, 1976); 3) F. C. Daibner, Animals of the Tidal Marsh (New York: Van Nostrand Reinhold, 1982); 4) Odum, et al. (68). Pholo credit: US Fishi and Wildlife Service, Jim Leupold A white-faced ibis tends its young in a marsh at Bear River National Wildlife Refuge. Many water birds depend on marsh vegetation for nesting sites Ch. 3— Wetland Values and the Importance of Wetlands to Man • 55 wildrice, and pondweed. In salt marshes, they feed heavily on cordgrasses. They occasionally eat in- sects, clams, and crayfish. In coastal areas, musk- rats reach their highest densities in brackish marshes dominated by bulrushes and cordgrasses. Another mammal, the nutria, is a related rodent that first was introduced from South America into Louisiana in 1938 for its fur. It is twice the size of the muskrat but is ecologically similar. Nutria prefer freshwater marshes, though they also may be found in low- to high-salinity marshes. Mink that inhabit wedands usually rely on cray- fish and frogs in the North-Central States and prey heavily on muskrats during droughts and periods of muskrat overpopulation. However, fish are the most important food for a North Carolina popula- tion of mink, and crayfish are most important for mink in Louisiana. Mink appear to use the different coastal wetlands with equal success. In general, however, densities of these mammals are higher in freshwater rather than saltwater marshes. Nutria are harvested for their fur in Louisiana, Maryland, the Carolinas, Texas, Oregon, and Washington. Mink and muskrat are taken in almost all States, though the majority are trapped in the wetland-rich States of the upper Midwest, the Dakotas, and Louisiana (68). In 1979-80, for in- stance, these species represented 32 percent of the total mammal-harvest value of approximately $295 million (for unfinished pelts)." This is a significant "Information on the economic value of wetland furbearers comes from two souixes; 1) Fur Resources Committee, International Associa- tion of Fish and Wildlife Agencies, fur harvest chart for the United Photo credit: U.S. Fish and Wildlife Service A nutria wading in a nriarsh at Belle Isle, La. These furbearers reach their greatest density In freshwater marshes, though they may also be found in low-to-high salinity marshes contribution to the fur industry, which recorded sales of almost $1 billion in 1980. Number Average Total value harvested' pelt price (rounded) Muskrat 8,634,753 $ 8.63 $74,526,548 Nutria . . 1,344,652 7.25 9,748,727 Mink . . . 394,214 22.42 8,838,277 •1979-1980 season. While mammals are harvested primarily for their pelts, they also are valuable for meat and various byproducts. During the 1979-80 season in Loui- siana alone, 582,000 lbs of nutria and 18,000 lbs of muskrat, both valued at $0.04/lb, were harvested for meat; their combined value was $24,000. Alligators. — Alligators are found in the wedands of the Southeast, from North Carolina to Texas, preying on a variety of vertebrates, including mam- mals, -birds, fish, and other reptiles. Alligators need shallow waters and banks for rest and warming in the sun. They use wetland vegetation for cover, protection, and nest construction. Controlled har- vest of wild alligators for their hides and meat is permitted in some areas of Louisiana. In 1979, over 16,000 alligators worth about $1.7 million were har- vested in the Louisiana coastal region (40). States and Canada (27 species), 1979-80. Figures in text for the United States alone; and 2) Eugene F. Deems, Jr., and Duzme Pursely, "North American Furbearers, A Contemporary Reference," International Association of Fish and Wildlife Agenrip<;, 1Q82 ./-■ ) i^^ Photo credit: U. S. Fish and Wildlile Service Alligators need shallow water and banks for rest and warming in the Sun. They use wetland vegetation for cover and nest construction 56 • Wetlands: Their Use and Regulation Crayfish. — Crayfish require the fluctuating water levels found in wetlands for mating and egg laying. Crayfish also feed primarily on wetland vegetation (46). Although there are commercial crayfish fisheries in Wisconsin and the Pacific Northwest, the most valuable crop comes from the Lower Mississippi River Basin, particularly Loui- siana. Approximately 25 million lbs, representing revenues of $11 million, are harvested annually.* Fish and Shellfish. — Many freshwater and salt- water fish require wetlands at some stage of their lifecycle.'^ Pike, pickerel, and muskellunge seem to prefer vegetated shallow water for broadcasting their eggs and may even spawn on land that is only temporarily flooded in the spring. '^ Large mouth bass spawn in the temporarily flooded zones of bot- tom land hardwoods. An abundant supply of in- vertebrates in these areas supply necessary food during a critical period after the fish eggs hatch (38). The alewife and the blueback herring spawn in freshwater tidal marshes and flood plain forests along the east coast (18). Members of the perch family (including wall- eyes), the sunfish family (including bluegUl, bass, and crappie), and the pike family (including pick- erel and muskellunge) commonly are found in veg- etated wetlands, owing to the protection from pred- ators afforded by the vegetation, strong currents, sunlight, and the fact that the prey of all these fish often take refuge in the wetland. Grey snapper, sheepshead, spotted sea trout, and red drum move into mangroves after spending their first few weeks in submerged seagrass beds. These fish feed heavily on either small fishes or amphipods (86). Juvenile marine fish and shellfish also use coastal marshes, particularly marshes of intermediate sa- linity, because this salinity excludes both marine and freshwater predators (2). (See table 5 for a list of species.) Pacific coast wetlands probably do not serve the same nursery function as do the Atlantic coast and gulf coast wetlands (68). •Calculation of the crayfish catch ($11 million, 25 million lbs), based on data supplied by Larry Delabreteonne. "Adamus and Stocl ■6 1 o o m o> •6 1 o u> c _o w w O > c o o < : S 5 ^ £ j >? o E >- 1. S cj o c o - J ^ S'S? « ^ C ro ^ O 5 - cf -5 ■= °^ 1 -D O _ — . ?|siis ™ ^ — ,c ! -o E 5 < - 5 OJ £ ^ <*i ; >- cu tn 1- fc ■ TO -2 aJ Q. I- ■ c: TO o . ^ ■D O O o -— — t_ O) I- '^ tn o ~ ■D nj c en o XI o c E EC o o 01 u c T3 ■r c c CO -E CO a. o n O UJ o ^ ■§ i = .2 ™ t: -So. o id ■ »- CI ^ n3 ^ C "3 CO ^g- ■D O 0) D) Q- S-5 c o til (1) >^ — T3 OJ E 5 c c s ™ ■CJ nj n> .^ Q ca •D O r = o o E " o c i. *> ? trt o Q. a. > o 00 - O "^ O S o "o ™ 0)£ fS cu (/I nJ E o? > — O — OJ E 3 to -is 'sit . (J J^ — 5 w) I- a> : ro o _ s ■=>■;; ^ ) c ^ en (U a> -<=> £3 ^ I— X3 in *-> o p -o ^ ^ 5 O) U) o o o >" S ' 2 £ o ! .2 "o Q- E > •* (J *- OJ TO f' ^- ™. *G E •^ S 5 = J2 £ o ™ — I -^"^ ~ E >-l 3 a> 5 S c5 _ Hi g 5g| en 5; == S < c E - — = g " " " T3 — S o TO 5 «.2 =^ (J in -n ™ »- lil o w -o E Z ~ " s ■^ lO (D O T3 03 > O a> — -^ = a> — CO 3 tr to cr e *= o ^ 2 S^ 7^ o> 2? O O o IT ai .^ CD « ^§ goo ■5=5 ™ o "5 U CO O. CD CO 5 E CO tu ^ CO to « c: a> o c ;2t3 t^ ts o I "> .E Pen = , ^il E . 1- T; in E o ™ :e s t ,_^-o tn C. CO C3> ^ CO r: :i to ^-^ ^ > C O ■? I ^ - ^ - 5 5 c ^ S E o to c/, 2 -= CO T3 -^ s *" s ™ 5 - ^ -o Ch. 5— Wetland Trends • 101 •a a> c o o ■o o 10 c _o 'io 91 > C o o a o < I ed n O (1) ■»- TD c c r 7= O 0) 1^ o O) " — T- E i; o r^ o m m ■^ (- o ^ E o ^ Q..E s en 5 i ^ ■p o CO 1^ en s B E t3 :=: a. -« "O __ o o c: o c i; TO (D CL "o ^ E t: CO -o ■o g in <-) i^ t ID CD lO o o O 3 to Ol ro b — m = (« > 2 -Q t« (D . 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Q. o '*— 1 £ 1 SS 8 Wl ■o « = c CO % re S CO £ TO <=> ^ -ac j= 3 9 i g o o "co o ^ cn o g X d) O) .E (U _c if ^ o en IZ g g ^ TD o o o ■ t: Q.-i= ■ CL> C CO " "(O — 5^ ; S "O Q. C O ^_^ s I"! & ^ (U s o 3 ° -o : E c^ E Q. ._ CO - E E CO- ™ O) rj E to "D E ™ «? c — > oj -Q E i ™ o e > E — Q. *" CO p o "s E-ir ■^ .„ o o CU CO Q. 03 o — - ^ m -C I- ^ (rt to O ■J- m •^ Q- CO to = ?-'■=: ^ S tf tf ^ c to o> = 11 c -o 03 a> . . ^ CO .Q ,^ > CO C k~ ^ e Q. S - Z - E O CO -=■ 5 S S 3 £ Moll I I (O ?:5 "55 S to 3 cn-Q ^ Ch. 5— Wetland Trends • 103 ■a « c o o o E UJ a. « o ■o c CD « « o. O « o «> c _o '« > c o o O) E 3 cn 5 if' .= £ |£ " cn o "5 ^ O o CO O "O ' o E ^ E , (U >v C "S "^ 5 s > > ^ a> o o o ^ o o o t f CD .2 « ■^ yj TO ^ £ s o <-^ i2 LO . " cn CD .Si. ■^ h- o c 'd O) CO c 3 O Jrt O S -^ I t tr a> ^ >^ 03 O c ~ > 3 O O C T3 O ,, ° 2 O. = 2? 5 ™ = o 2 <— ^ '^ OJ o C ■^ "O ~~ — <=• « -o -o trt c: 03 5 = - £ S3 I ■g " 3 E , 8! =3^ S =3 T3 O L= ■D ^ H 3 (rt 104 • Wetlands: Their Use and Regulation E Q. O CO E o M « M (0 o -I ■o c n « I d 10 CO ^ Q. "^ ^ O w E ° c= oj S O '(/J E o Q. F (J ■o o CD 2= (1) uy Q. ■2 ^ c c E C) U) =1= ra 0) 1 ? nr tT3 ^ 5 E E *" _■ E to .= ^ CD CT) O 3 O T- « «« «■, - <» X -^ « ™ cn * a> -^ ro o >• c= ^ ^ •- 9 ™ m V > J:; __ ™ " s s ■o o o o ^ * "O P o 2 e q: 1- Ol -^ O cu ^ ~ > rtj o ^ « tr; Q. CO o "IJ J2 b ™ I oj r^ "t E > CT) a> o ^~ 5 o .2 ra a> a> (D > F 2 g I ° I " •E S g lU ^ ^ e -o ^ o ra j; ^5 ^ •D Zi S x: o TO *5 " E I s SE I ^ -o S ! 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' si li >- CT •D C en S S -5^ E c - E S S to ^ o =£ c o o c « E a. o « > o CB E o « M ! n to (rt QJ f ; S g g i ■ S E CO a: E 2 E ^ If *- £ CD O 3 t/3 *i a> ™ c c P ro o o Tl CO ■" o QJ 2 xa : ui oj ^ i: , c: ^ « ^ S ^ o o cu o H s 8 -s e S s is E =1 c> en ^ ^ J5 c ^^ ^ to :> ^ ro CO ~ o °5 = > o c I c II i - 2 " -a ro cn ' C O ™ i5 *- 2? t: o Q. £ " E (T3 T3 -o -o C ,_ C C S o ra ro — a — — ra o fo i:; 3-0 £ ^ O O 03 ^ Q- CC QC £ ; £1 g s < ;.°s ! 5 _• 'fie i:; to ra s iie a> t § i_n en 01 T3 'm c r^ "O ci ci § 106 • Wetlands: Their Use and Regulation 0) U < E o (0 o « C4 to TD go ^ or, = .2 c: c c/l ^ — § O) ~ S s ^ -E I ^ C V> 03 O ^ o. o in E « — ^J ■p r\j o F 3 E O S a ?fi CL e CL fc CL Q. 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Si^ 5 S-o — r cn.TO c E — ■■ - 3 2 O) ^5 .— to o 9- c - o 03 rt] aj !i; m o> — o3 > TO t: (^ > 03 C o ™ . c -a TO CI. 5 C3 03 O w E p i» .9 o g !5 ■" sis "E S s ■o IS L^ Ol c to 1.1 "J ^ _ T3 ° O, = ™ (O c 2 *" c^ ? >; 55 cc a™ : 00 -J ■ oi TO UJ U- Ch. 5— Wetland Trends • 107 •a « o o (0 « < E p M 9 M 0) o « I, « n c o "- 6 ^ -•- o — to (/) — to "O I " s e|.e tn ai .52 > S =• c 1^ ■- t; ''^ 73 5:2 I c o « o - ^ f "i CL O Si 2 CD ■o E TO Is E"? ■~ « CD ■O TD c TO TO ■— 8 5>i — -° 2 .2 = 0-2 2 a "> g - I- O TO TO O c >. C E — TO t QJ C " » C O tJ to TO 2? Q. Qj O c e " - ._ - - 23 (rt ^- o ^ Q- (U to *- s c « ™ = » i * S o " ■■= 1= ic S S i = " ™ Ss-tl -i-o ~ o ■2 - S >^ TO S "^ ^ c — « g o TO 03 to -o ° : O ^ "= oj to S .E "o 3 o -^ £ o>a, ;;;■« '^ t/3 0) O C/l OJ (/I o "5 IS o 2 213 £ -sew™ TO o oj — « ■« > S = is <" o 1 ir- is ._? "O TO S23 E OJ o ■ o g " S E C3) O TO s i ^ s £ E c > Q. O TO ■o to — ■ 5 s F CD CO TO CD F O S W5 ~ ■H. to TO 5 * ID 1 TO ■o