Status and Trends of Wetlands from 2004 to 2009

8/13/2019 Status and Trends of Wetlands from 2004 to 2009

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U.S. Department of the Interior

Fish and Wildlife Service

and

National Oceanic and Atmospheric

Administration

National Marine Fisheries Service


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Status and Trends of WetlandsIN THE COASTAL WATERSHEDS OF THE CONTERMINOUS UNITED STATES

2004 to 2009


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Status and Trends of Wetlandsin the Coastal Watersheds of theConterminous United States2004 to 2009

Thomas E. DahlU.S. Fish and Wildlife ServiceandSusan-Marie StedmanNOAA, National Marine Fisheries Service


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Acknowledgments

The authors would like to recognize key individuals from their respective agencieswho have supported the completion and review of this study. Specifically, from the

U.S. Fish and Wildlife Service, Gary Frazer, Assistant Director, Ecological Services;

Paul Souza, Deputy Assistant Director, Ecological Services; Martha Balis-Larson,

Chief, Division of Budget and Technical Support; Jonathan Phinney, Chief, Branch

of Geospatial Mapping and Technical Support. From the National Oceanic and

Atmospheric Administrations National Marine Fisheries Service; Tom Bigford, Chief,

Habitat Protection Division, Office of Habitat Conservation; and Buck Sutter, Director,

Office of Habitat Conservation.

Peer review of the study findings and report was provided by the following subject mat-

ter experts: Jim Dick, U.S. Fish and Wildlife Service, Regional Wetlands Coordinator,

Albuquerque, NM; Mark Gernes, Research Scientist, Minnesota Pollution Control Agency,

St. Paul, MN; Virginia Hansen, U.S. Environmental Protection Agency, Gulf Ecology

Division, Gulf Breeze, FL; Dr. Mary Kentula, U.S. Environmental Protection Agency,

National Health and Environmental Effects Research Laboratory, Western Ecology

Division, Corvallis, OR; William Kirchner, U.S. Fish and Wildlife Service, Regional

Wetlands Coordinator, Portland, OR; Emily Sheehan, ORISE Fellow, U.S. Environmental

Protection Agency, Office of Wetlands, Oceans and Watersheds, Wetlands Division,

Washington, D.C.

A Technical Review Team from the U.S. Fish and Wildlife Service was responsible for

ensuring the validity of standard operating procedures, technical protocols, project

documentation and quality assurance. Key personnel from the National Standardsand Support Team in Madison, WI contributed considerable efforts to this project

including Mitchell T. Bergeson, Geographic Information Systems Specialist; Andrew Cruz,

Information Technology Specialist; Jane Harner, Geographic Information Analyst,

Rusty K. Griffin, Physical Scientist and Sydney Nick, Geospatial Analyst.

Myra Price, U.S. Environmental Protection Agency, Office of Wetlands, Oceans and

Watersheds, Wetlands Division, Washington, D.C. assisted in field verification work in

both the Gulf of Mexico and the Pacific coastal regions. Technical review and editorial

assistance was provided by Dr. Bill Wilen and Jo Ann Mills, U.S. Fish and Wildlife

Service, Headquarters, Arlington, VA.

Partial funding for this study was provided by the U.S. Environmental Protection Agency,Office of Wetlands, Oceans and Watersheds, Wetlands Division.

This report should be cited as:T.E. Dahl and S.M. Stedman. 2013. Status and trends of wetlands in the coastal watersheds

of the Conterminous United States 2004 to 2009. U.S. Department of the Interior, Fish and Wildlife Serviceand National Oceanic and Atmospheric Administration, National Marine Fisheries Service. (46 p.)


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Conversion Table

U.S. Customary to Metricinches (in.) x 25.40 = millimeters (mm)

inches (in.) x 2.54 = centimeters (cm)

feet (ft) x 0.30 = meters (m)

miles (mi) x 1.61 = kilometers (km)

square feet (ft) x 0.09 = square meters (m)

square miles (mi) x 2.59 = square kilometers (km)

acres (A) x 0.40 = hectares (ha)

Farenheit degrees (FE) 0.5556 (FE-32) = Celsius degrees (CE)

Metric to U.S. Customary

millimeters (mm) x 0.04 = = inches (in.)

centimeters (cm) x 0.39 = inches (in.)

meters (m) x 3.28 = feet (ft)

kilometers (km) x 0.62 = miles (mi)

square meters (m) x 10.76 = square feet (ft)

square kilometers (km) x 0.39 = square miles (mi)

hectares (ha) x 2.47 = acres (A)

Celsius degrees (CE) 1.8(CE) + 32 = Fahrenheit degrees (FE)

General Disclaimer

The use of trade, product, industry, or rm names or products in this report is for informativepurposes only and does not constitute an endorsement by any agency of the U.S. Government.

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v

Table of Contents

Executive Summary .........................................................................................................1Introduction.....................................................................................................................4

Coastal Wetlands.............................................................................................................6

Study Area .....................................................................................................................10

Study Methods...............................................................................................................12

Habitat Denitions ........................................................................................................13

Study Limitations ...........................................................................................................14

Results: Status of Wetlands in Coastal Watersheds, 2009 ...............................................16

Changes in Wetlands of the Coastal Watersheds, 2004 to 2009.....................................20

Trends in Saltwater Wetlands, 2004 to 2009 .................................................................22

Trends in Coastal Freshwater Wetlands, 2004 to 2009 ..................................................26

Discussion .....................................................................................................................32Summary ......................................................................................................................38

References Cited............................................................................................................40

Appendix: Denitions of Habitat Categories ..................................................................43


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List of Figures

Figure 1. Aerial view of saltwater (intertidal) wetlands that include emergentsalt marsh and non-vegetated shoals and sandbars ...............................................5

Figure 2. Coastal mangroves colonize intertidal areas along the coast of thesouthern United States ..........................................................................................7

Figure 3. Saltwater marshes of a coastal watershed along the Gulf Coast of Louisiana .....7

Figure 4. Freshwater wetlands of a coastal watershed in Alabama ...................................7

Figure 5. Storm damage and saltwater inundation resulting from Hurricane Irenealong the coast of North Carolina in 2011 ...........................................................8

Figure 6. Tidal waters ood a city street in Key West, Florida ..........................................8

Figure 7. Changes in population density in the United States from 1980 to 2008 ............9

Figure 8. Coastal Watersheds of the Conterminous United Statesas used in this study ............................................................................................11

Figure 9. Freshwater and saltwater wetland by area in the coastal watersheds, 2009 .....16Figure 10. Percent of all coastal wetland area by coastal region, 2009 ..........................17

Figure 11. Relative wetland density of the coastal watersheds along the Atlantic, Gulf of Mexico, Great Lakes and Pacic as determined by this study, 2009 ........17

Figure 12. Saltwater (intertidal) wetland distribution (area in acres) by coastalregions, 2009......................................................................................................19

Figure 13. Rocky shoreline along the coast of California................................................19

Figure 14. Freshwater wetland distribution (area in acres) by coastal regions, 2009 .......19

Figure 15. Wetland gains and losses in the coastal watersheds of eachcoastal region between 2004 and 2009 ..............................................................20

Figure 16. Attribution of loss or conversion of saltwater wetlands in the coastal

watersheds of the Atlantic, Gulf of Mexico and Pacic, 2004 to 2009 ................22Figure 17. Coastal watersheds of the upper Gulf of Mexico showing the magnitudeof intertidal (saltwater) wetland loss to open water, 2004 to 2009......................23

Figure 18. Tidal saltmarsh in coastal Washington ..........................................................25

Figure 19. Estimated losses and gains in area for the freshwater wetlandtypes in the coastal watersheds, 2004 to 2009 ....................................................26

Figure 20. Forested wetland losses in the coastal watersheds of theSoutheastern U.S. (North Carolina to Texas) as attributed to uplandland use categories, 2004 to 2009 ......................................................................27

Figure 21. This aerial image shows the proliferation of freshwater ponds in asouth Florida coastal watershed overtaken by development ................................30

Figure 22. Attribution of loss or conversion of freshwater wetlands in the

coastal watersheds, 2004 to 2009 .......................................................................31Figure 23. The term Other lands has been used to describe land in transition

when it was not possible to categorize a distinguishable land use(i.e. urban or agriculture) ....................................................................................33

Figure 24. A residential housing development built on lled wetland in the upperportion of a coastal watershed in Louisiana ........................................................35


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List of Tables

Table 1. Area (in acres) of coastal watersheds and shoreline (in miles)included in this study..........................................................................................10

Table 2. Wetland, deepwater and upland categories used to conduct this study. ...........14

Table 3. Estimated freshwater wetland area in the coastal watershedsof the Atlantic, Gulf of Mexico, Great Lakes and Pacic ascompared to the conterminous United States, 2009 ............................................18

Table 4. Changes in wetland area for the coastal watersheds of theAtlantic, Gulf of Mexico, Great Lakes and Pacic, 2004 to 2009 ........................21

Table 5. Estimated status and change in wetland area for selectedcategories in the coastal watersheds of the Atlantic,Gulf of Mexico, Great Lakes and Pacic, 2004 to 2009 ......................................21

Table 6. Estimated changes to saltwater (intertidal) wetlands of the Atlantic,

Gulf of Mexico and Pacic coastal watersheds, 2004 to 2009 ............................24Table 7. Estimated changes to freshwater wetlands of the Atlantic,

Gulf of Mexico, Great Lakes and Pacic, 2004 to 2009 ......................................28


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Executive Summary

Coastal wetlands in the United States are diverse andinclude both saltwater wetlands that occur along thecoastal shorelines and freshwater wetlands that extendinland within the coastal drainages. Inuenced by waterthat connects the upper reaches of the watershed withthe oceans or Great Lakes, these wetlands play a pivotalrole in the watershed. Wetlands in coastal watershedsprovide crucial habitat for wildlife by providingspawning grounds, nurseries, shelter, and food for nsh,shellsh, birds and other wildlife. These wetlands alsohelp improve water quality by ltering and detoxifyingrunoff from residential, agricultural, and urban areas.Furthermore, there is an increasing awareness of the

important role these coastal wetlands play in bufferingcoastlines against storm and wave damage and instabilizing shorelines in the face of climate changeimpacts.

In 2008, the U.S. Fish and Wildlife Service (USFWS) incoordination with the National Oceanic and AtmosphericAdministration (NOAA) released a report documentingwetland trends in the coastal watersheds of the Atlantic,Gulf of Mexico and Great Lakes (Stedman and Dahl2008). That study did not include the wetlands in thecoastal watersheds along the Pacic coast. Findingsfrom that study indicated that there was a net loss of

an estimated 361,000 acres of wetland in the coastalwatersheds of the eastern U.S. between 1998 and 2004.There was considerable variation in trends among thethree coastal regions studied. Watersheds of the GreatLakes experienced net gains in wetlands, whereaswatersheds along the Atlantic and Gulf of Mexico

coasts experienced an overall net loss of an estimated60,180 acres annually. Attribution of these lossespointed to development and other human activities asthe principle cause of loss in the Gulf of Mexico and saltwater intrusion or inundation as the primary cause of thelosses observed in the mid-Atlantic region. The release ofthat information stimulated discussion at the Federal levelcentering on the need for increased wetland protectionand restoration measures in the coastal watershedsand the role of federal, state or local mechanisms inprotecting these coastal resources.

Working in conjunction with principal Federal agencies

the USFWS and NOAA have produced updated data onmore recent trends of wetlands in the coastal watershedsto help prioritize conservation planning efforts andcontribute additional information on coastal wetlandtrends.

This report updates and expands previous information oncoastal wetland loss by incorporating new data for thecoastal watersheds of the Atlantic, Gulf of Mexico andGreat Lakes and in addition, providing information forthe Pacic coast along the States of Washington, Oregonand California. It presents the latest status informationon coastal wetland resources and provides estimates of

losses or gains that occurred in the coastal watershedsin the conterminous U.S. between 2004 and 2009. Theinformation presented provides data on the areal extent ofwetlands but does not assess wetland condition or otherqualitative changes to wetlands in coastal watersheds.

Suison Marsh, California


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2 Status and Trends of Wetlands in the Coastal Watersheds of the Conterminous United States 2004 to 2009

To estimate wetland extent and change, this studyused randomly selected 4.0 square mile (2,560 acresor 1,036 ha) sample plots and digital high-resolution

imagery to identify change in wetlands, deepwaterhabitats and uplands. A total of 2,614 plots were used tosample the coastal watersheds and ground vericationwas done for 380 plots (14.5 percent). Wetlands anddeepwater habitats were described using the USFWSbiological denition of wetland (Cowardin et al.1979)and followed the procedural, quality control and analysisprotocols as have been developed for the NationalWetlands Status and Trends reporting conducted byUSFWS.

In 2009, there were an estimated 41.1 million acres ofwetlands in the coastal watersheds of the United States.

This area represented 37.3 percent of total wetlandarea in the conterminous U.S. Of the wetland area inthe coastal watersheds, an estimated 34.6 million acres(84.3 percent) were freshwater wetlands and 6.4 millionacres (15.7 percent) were saltwater wetlands. Between2004 and 2009, wetland area in the coastal watershedsof the U.S. declined by an estimated 360,720 acres. Theaverage annual rate of change was an estimated loss of80,160 acres, a 25 percent increase in the rate of wetlandloss from the previous reporting period1. The increase inthe rate of coastal wetland loss was statistically signicant(p = 0.007) when results from this study were comparedto the coastal wetland loss estimates from the 1998 to

2004 study as reported by Stedman and Dahl (2008).

The watersheds of the Atlantic and Gulf of Mexico hadvery similar amounts of wetland area (15.9 million and15.4 million acres, respectively) in 2009. Watershedsof the Great Lakes had an estimated 8.5 millionacres of wetland. The Pacic coastal watersheds hadthe least amount of wetland area with an estimated1.3 million acres. The Atlantic, Gulf of Mexico, andPacic coastal regions experienced net wetland lossesbetween 2004 and 2009 of 111,960 acres, 257,150 acresand 5,220 acres, respectively. The watersheds of theGreat Lakes region experienced a net gain in wetland

area of an estimated 13,610 acres. Seventy one percentof the estimated wetland losses were in the coastalwatersheds of the Gulf of Mexico.

1The average annual rate of loss for the six years between 1998 and2004 was 59,000 acres compared to the average annual rate of loss forthe 4.5 years between 2004 and 2009 being 80,160 acres.

Saltwater wetlands sustained an estimated net loss of95,000 acres as modest gains in marine and estuarinenon-vegetated wetlands (ats, shoals and bars) were

overshadowed by losses of estuarine vegetated wetlands,which declined by 2.4 percent. Most of the vegetatedestuarine losses were to open saltwater deepwater habitats,and virtually all of these losses occurred in the Gulf ofMexico.

In the freshwater system, emergent marshes and shrubwetlands increased in area; however, freshwater forestedwetlands declined by an estimated 405,700 acres resultingin a net loss of freshwater vegetated wetland area of328,800 acres (1.0 percent) between 2004 and 2009.Forested wetlands lost to uplands in silviculture accountedfor an estimated 179,080 acres or 65 percent of the

freshwater wetland losses to upland land uses. Regionally,the Pacic coast sustained a small net loss (5,180 acres) offreshwater wetlands, while the Atlantic experienced largernet losses of 112,290 acres, the Gulf of Mexico sustainednet losses of 161,870, and the Great Lakes saw a modestnet gain of 13,610 acres in their coastal watersheds.

The area of freshwater ponds increased by almostsix percent, although many were located in urban orsuburban developments as likely water detention pondsor ornamental ponds as opposed to targeted wetlandreestablishment projects. The vast majority of these newponds (99 percent) were constructed in the watersheds of

the Atlantic and Gulf of Mexico.

Although both saltwater and freshwater wetlands sustainednet losses between 2004 and 2009, some coastal wetlandgains occurred through reestablishment projects. Thesewere most prevalent on agricultural lands primarily in thecoastal watersheds of the Great Lakes, South Carolina,Georgia, and the upper reaches of the watersheds incentral Florida. In general, wetland reestablishment incoastal watersheds has lagged behind reestablishment ratesobserved nationally for a variety of reasons. A strategyof achieving no net loss by offsetting wetland acreagelosses with wetland creation or reestablishment does not

appear to be effective in the coastal watersheds as wetlandlosses have increased in some coastal regions. Continuinglosses of wetlands in coastal watersheds have direct costsfor people and longer-term resource implications for sh,wildlife and other natural resources.


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Executive Summary 3

Black Skimmers (Rynchops niger), Laughing Gulls (Leucophaeus atricilla), Sandwich Terns (Thalasseus sandvicensis), Gulf coast

of Florida

This report is the result of a cooperative effort between the U.S. Department of the Interiors Fish and

Wildlife Service and the National Oceanic and Atmospheric Administrations National Marine Fisheries

Service. Continuing efforts to monitor coastal wetland status and trends described in this report have

been supported by the Federal Interagency Coastal Wetlands Workgroup a multi-agency group

comprised of members from the Environmental Protection Agency, NOAA, USFWS, U.S. Army Corps

of Engineers, Natural Resources Conservation Service, the Federal Highway Administration and the

U.S. Geological Survey.


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Introduction

Coastal wetland ecosystems include not only thewetlands adjacent to the ocean coast or Great Lakesbut also those within the coastal watershed boundary(NOAA 2012). Thus coastal wetlands included in thestudy can be described as all wetlands in each 8-digithydrologic unit code2watershed that drains directly tothe ocean coast and contain a tidal waterbody, as wellas watersheds that drain directly to one of the GreatLakes. Both saltwater and freshwater wetlands areincluded within this watershed-based ecosystem concept.Mangrove forests, fresh and saltwater marshes (Figure 1),forested and shrub wetlands, coastal shoals, tidal mudats, sand spits (bars), beaches, tidal pools and freshwater

ponds occur in coastal wetland ecosystems.

The Federal Government, working closely withStates, other partner organizations, and the publichas a crucial role to play in identifying stressorsfacing coastal environments and in developing andimplementing actions that ensure the continued healthand availability of our Nations ocean, coastal, and GreatLakes resources. The U.S. Fish and Wildlife Service(USFWS) and the National Oceanic and AtmosphericAdministrations National Marine Fisheries Service(NOAA Fisheries) have collaborated in a number ofefforts to produce information on coastal wetland habitats

as they inuence sh and wildlife species distribution,enhance the physical or ecological condition of coastalareas (e.g. storm surge protection and water qualityimprovement) and provide socioeconomic benets tomany Americans.

In 2008, USFWS in conjunction with NOAA releaseda report documenting wetland trends in the coastalwatersheds of the Atlantic, Gulf of Mexico and GreatLakes (Stedman and Dahl 2008). The ndings fromthat study indicated that an estimated 38 percent of allwetland acreage in the conterminous United States wasfound in these coastal watersheds. Coastal watersheds

had sustained an estimated 361,000 acres of wetlandloss between 1998 and 2004 or an average of nearly60,000 acres each year. The loss of these coastal habitatsdiminished the health of these ecosystems and reducedtheir ability to provide environmental and socioeconomicservices (Wolanski et al.2009). The release of that reportstimulated discussion at the Federal level centering onincreased wetland protection and restoration measures inthe coastal watersheds. Monitoring of coastal indicators

including wetland loss has shown that coastal planningand management policies over the past 30 years havelimited, but not curtailed, harmful cumulative impactson coastal ecosystems (USEPA 2012). As a result, thereis continuing interest in the effectiveness as well as thelimitations of federal, state or local mechanisms to protectthese coastal resources.

In response to concerns about the rate of wetlands loss incoastal watersheds, the Environmental Protection Agency(EPA) has been leading an interagency effort to examinewetland losses in coastal watersheds and identify stressors,strategies, policies and information to protect and restore

coastal wetland resources. This interagency effort hasa goal to raise awareness of coastal wetland functions,threats and conservation opportunities to reverse losses ofwetlands in coastal watersheds. The Interagency CoastalWetlands Workgroup (ICWWG) established by EPA alsoincludes NOAA, USFWS, U.S. Army Corps of Engineers,Natural Resources Conservation Service, Federal HighwayAdministration and the U.S. Geological Survey. With thesupport of the ICWWG, EPA and NOAA held a seriesof seven workshops in coastal watersheds3, solicitinginformation and views from those most familiar withwetland issues in those watersheds regarding wetlandstressors, effective tools and strategies for reducing wetland

loss in coastal watersheds. The results of those workshopshave been published in a set of regional reports availableon the EPA and NOAA web sites (USEPA 2013a; 2013b).

At roughly the same time, USFWS embarked on a nationalupdate of the National Wetlands Status and TrendsStudy for the time period from 2004 to 2009. Workingin conjunction with principal Federal agencies,4thatstudy formed the basis for this update on the status and

2 Drainage basins in the United States have been divided and sub-divided at four different levels and each assigned a unique hydrologicunit code consisting of eight digits based on these four levels.

3 Workshops were conducted in the following watersheds: Cape Cod,Delaware Estuary, York River (VA), Lower and Middle Neuse River (NC),Indian River (FL), Mississippi Coastal, and Galveston Bay.

4Funding or technical assistance for the National Wetlands Status andTrends study was provided by the Environmental Protection Agency,Department of Agriculture (Natural Resource Conservation Service),Department of the Army (Army Corps of Engineers), National Oceanic andAtmospheric Administration (National Marine Fisheries Service) and theDepartment of the Interior (Fish and Wildlife Service). Additional supportfor work in the coastal watersheds was provided by EPA and NOAA.


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more recent trends of wetlands in coastal watersheds.This report expands the information for the coastalwatersheds of the conterminous U.S. by updating datafor the coastal watersheds of the Atlantic, Gulf of Mexicoand Great Lakes, which were included in the previouscoastal watersheds report, and adding information for thePacic Coast along the States of Washington, Oregon andCalifornia.

This report presents the latest status information oncoastal wetland resources and provides estimates oflosses or gains5that occurred in the coastal watershedsin the conterminous U.S. between 2004 and 2009.

The information presented provides data on theareal extent of wetland types, both past and present,to help prioritize conservation planning efforts forcoastal wetland resources and contribute additionalinformation to the ICWWG to facilitate strategy andpolicy development. Additional wetland impactshave occurred in non-coastal watersheds whichcumulatively drain to coastal waters and thus have anadditive inuence on coastal ecosystems (Dahl 2011).This increases the importance of coastal wetlandsin ecosystem interchange and function. This studydoes not assess wetland condition or other qualitativechanges to wetlands in coastal watersheds. Readersare referred to the National Coastal Condition ReportIV (USEPA 2011) for information on the qualitativeaspects of coastal resources.

5Wetland loss or gain as used in this report is dened as a decline orincrease in wetland area.

Introduction 5

Figure 1. Aerial view of saltwater (intertidal) wetlands that include emergent salt marsh and non-vegetated shoals

and sandbars (foreground). Atlantic coastline of Virginia, 2008.


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Coastal Wetlands

Wetlands in coastal watersheds are part of a diverse andcomplex set of ecosystems that are vital to the Nationseconomy and an important part of our natural heritage.Centuries ago, coastal wetlands and estuaries providedthe sh, waterfowl and building materials that supportednative populations and European settlers. That vital rolecontinues today, with more than half of the sh caughtfor recreational or commercial purposes in the U.S.depending on estuaries and their coastal wetlands atsome point in their life cycles (Lellis-Dibble et al.2008).Other wetlands in the coastal watersheds providenurseries, shelter and food for nsh (Figure 2), shellsh,shorebirds and marine mammals (Twilley et al.1996;

Spalding et al.2010). Coastal wetlands also provideresting, feeding and breeding habitat for 75 percent ofthe Nations waterfowl and other migratory birds (USEPA2005; 2012). Healthy coastal wetlands are among themost productive ecosystems on the planet, comparableto rainforests and coral reefs. That productivity isparticularly important to the nearly 45 percent of theNations endangered and threatened species that dependon wetland habitats (USFWS 1995).

In addition to providing habitat for sh and wildlife,wetlands in the coastal watersheds benet humansby improving water quality (through the ltering and

detoxifying of runoff), protecting coastal communitiesagainst damage from erosion and ooding, and providingrecreational opportunities for wildlife viewing andexploration, hunting, shing and tourism. The overalllevel of economic activity generated in all coastalcounties in the U.S. is over $6.6 trillion or just under halfof the Nations gross domestic product in 2011 (NOAA2012). Because they provide such crucial services it isin our national interest to responsibly use, conserve andprotect these coastal resources.

Coastal wetland types are diverse and include saltmarshes (Figure 3), mangrove swamps, freshwater

forested swamps (Figure 4), at-woods, freshwatermarshes, shrub depressions and wetlands adjacent totidal rivers. The denitive factor in describing coastalwetlands is the tidal inuence and hydrologic connectionof the watershed with the ocean (or the Great Lakes).

For this reason, coastal wetlands can be described as allwetlands in watersheds that drain to the Atlantic Ocean,Gulf of Mexico or Pacic Ocean, and contain a tidalwaterbody; as well as wetlands that drain directly toone of the Great Lakes.6All wetlands in these coastalwatersheds formed the target population included inthis study.7This landscape-level or ecosystem-basedapproach encompasses concepts fundamental to workingtoward integrated, comprehensive policy development,management and conservation of our coastal resources.

The distribution and condition of wetlands in coastalwatersheds are strongly inuenced by natural processes.

Both man-made and natural stressors inuence wetlandabundance, type, distribution and vulnerability tochanges. Saltwater wetlands are found at the interface ofland and sea where they form linkages between inlandlandscapes and the ocean. These intertidal wetlandsexperience oceanic inuences in areas of high energywhere tides, winds, waves and currents alter shorelinesand inundate coastal landscapes (Figures 5 and 6).Wetlands along this interface are subject to erosion,saltwater inundation, salinity changes, land subsidenceand changes in sediment deposition patterns. Coastalwetlands in the upper parts of a watershed are subjectto less erosion, but may still be affected by the other

factors mentioned. In some situations coastal wetlandscan adapt to these changes in a number of ways, such asmoving inland with rising sea level, changing vegetationcomposition or distribution in response to salinitychanges, or colonizing new areas when spits or barrierislands change location. However, human impacts on thelandscape can impede the ability of coastal wetlands toadapt to their dynamic environment.

6NOAA has used a specic methodology to identify coastal water-sheds using hydrologic unit boundaries that contain tidal water bodies.This excludes several areas that actually drain to one of the coastlines(i.e. surrounded by coastal watersheds) but do not contain tidal water

bodies. There may also be limitations due to the precision of watershedboundary demarcation.

7 The Pacic coast included watersheds in Washington, Oregon andCalifornia.


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Figure 3. Intertidal (saltwater) marshes of a coastal

watershed along the Gulf of Mexico, Louisiana.

Figure 4. Freshwater wetlands of

a coastal watershed, Alabama.

Coastal Wetlands 7

Figure 2. Mangroves colonize

intertidal areas along the coast of the

southern United States.


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Figure 5. Storm damage and saltwater inundation resulting

from Hurricane Irene along the coast of North Carolina, 2011.8

In addition to the property damage and threats to coastal

residents, the frequency and intensity of coastal storms can

also influence coastal wetland types and distribution through

erosion, deposition of sediments or by increasing salinity.

8The impacts of Hurricane Irene (2011) or Hurricane Sandy (2012)

were not included in this study timeframe.


Figure 6. Tidal waters flood a city street in Key West, Florida.

Rising sea levels, saltwater inundation or coastal storms are a

concern along certain coastlines.


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Losses and degradation of wetlands in coastal watershedscan be directly traced to population pressures andconversion of wetlands to developed or agricultural uses,

with resulting changes in water ow, increased pollutionand habitat fragmentation (Stedman and Dahl 2008).As human habitation in coastal areas has increased,population density in the coastal counties has risen tobe far greater than that of non-coastal counties (Crossettet al.2004). For example, in coastal North Carolina,the lands situated between the ocean and the interiorhave exhibited consistently higher growth of residentialdevelopment than lands far from the coast (Crawford2007), and that same trend can be seen elsewhere inmany coastal states. However, census data understate theimpacts of development in many coastal areas becausethey do not account for seasonal inuxes of residents

and the related infrastructure needed to support coastal

oriented tourism and growth (Beach 2002). Coastaldevelopment often contributes to land use changes thatincrease impervious surface area, affect water quality

or disturb natural habitats through loss or fragmentation(Crawford 2007). The effects of development onwetlands are important as some estimates indicate thatdevelopment will cover one quarter of the land area ofthe Nations coastal watersheds by 2015 (Beach 2002).Figure 7 shows the increase in population in coastalcounties in the conterminous U.S. These increases inpopulation density are frequently associated with greaterdemands for resources (USEPA 2013a) and wetlands incoastal watersheds are more likely to be lost or degradedwhen wetlands come into conict with land developmentinterests or other stressors associated with urbanization,infrastructure development, or land-use changes that alter

hydrology (Dahl 2011).

Non Coastal Counties

Coastal Counties

1970 1980 1990 2000 2010

Year

450

400

350

300

250

200

150

100

50

0

PersonsperSquareM

ile

Coastal Wetlands 9

Figure 7. Changes in population density in the conterminous United States from 1970 to 2010. Data adapted from NOAA

(2012).


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Study Area

The study area was the coastal watersheds of the

Atlantic, Great Lakes, Gulf of Mexico and Pacic coasts(Figure 8). NOAA uses a specic methodology (NOAA1999) to identify coastal watersheds by combininginformation on the extent of ocean-derived tidalinuence and the mapping of watershed (drainage)boundaries. The 8-digit hydrologic unit watershedsthat contained tidal water bodies were used to denotecoastal watersheds for this study. A similar method wasused in the Great Lakes region to identify the extent ofnon-tidal coastal watersheds of the Great Lakes.

The outer coastal boundary was determined by theextent of the coastal sampling frame used by the

FWS National Wetlands Status and Trends Studyfor the Atlantic, Gulf of Mexico, Pacic and GreatLakes coastal areas. The total area sampled in thesefour coastal areas was 246.9 million acres9(Table 1).The inland study boundary coincided with thecorresponding coastal watershed boundaries asprovided by NOAA however, along the Pacic coast,this inland boundary was truncated by the Coast RangePhysiographic Region boundary. The San Francisco Baywas also modied to include Sourin Bay.

The Atlantic coastline extends approximately2,070 miles from Maine to south Florida. Coastal

regions vary considerably from the steep rockyshorelines of New England to broad, at coastalmarshes in the Carolinas and the limestone landscapesof south Florida. Much of the Atlantic coast is typiedby large coastal bays and sounds including DelawareBay, Chesapeake Bay, Albemarle Sound, PamlicoSound and the Indian River Lagoon. Barrier islands

such as North Carolinas Outer Banks provide physical

barriers between waves and tidal energy of the oceanand mainland features. Tidal stages range between a fewinches in the Carolinas to 7 to 13 feet in parts of NewEngland (USEPA 2012). The negative effects of humanhabitation on coastal wetlands and other natural resourcescan be readily seen in the urban corridor that stretchesfrom New York City to Washington D.C. (National FishHabitat Board, 2010). The coastal counties along theSoutheast Atlantic had the largest rate of populationincrease (79%) of any coastal region in the conterminousUnited States between 1980 and 2006.

The Gulf of Mexico has about 1,630 miles of shoreline

extending from the subtropical reefs of the Dry Tortugasin Florida to the extensive coastal ats and marshes of theTexas coast. The Mississippi delta (including Baratariaand Terrebonne Bays) and its associated habitats are amajor feature of this coastal area, as are Tampa Bay,Mississippi Sound and Galveston Bay. Engle (2011) hassummarized some of the ecosystem services provided bywetlands along the Gulf coast. The economic importanceof the resources in the Gulf were recently underscored bythe Deepwater Horizon oil spill in 2010,10which affectedhundreds of species of resident and migratory wildlife,commercial and recreational shing, tourism and regionalbusinesses of many types. A majority of the wetland loss(61,800 acres) found in coastal watersheds between 1998and 2004 occurred along the Gulf of Mexico. Some of thatloss was associated with the long-term continuing erosionand subsidence of the Mississippi delta, but more wasrelated to development and other human activities alongthe entire coastline (Stedman and Dahl, 2008).

9 This study incorporated some estuarine embayments not includedin the total land area gure.

10This study did not include any wetland losses due to the DeepwaterHorizon oil spill in 2010 since the effective dates of data collection forthis study were between 2004 and 2009.


Table 1. Area (in acres) of coastal watersheds and shoreline (in miles) included in this study (shoreline information courtesy of

NOAA, National Ocean Service).Coastal Watershed

Area of Coastal Watersheds(acres)

Coastline (miles) Tidal Shoreline (miles)

Atlantic Coast 89,096,000 2,070 28,670

Gulf Coast 67,562,000 1,630 17,140

Great Lakes (United Statesonly)

55,869,000 5,180(including connecting rivers)

NA

Pacic Coast 34,372,000 1,290 7,860

Total 246,899,000 10,170 53,670


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Recognized collectively in federal law as the Nationsfourth seacoast, the Great Lakes and their connectingchannels and rivers comprise the worlds largest bodyof freshwater (U.S. Commission on Ocean Policy 2004).The watersheds of the Great Lakes encompass a diversityof habitats including glacial scours, coniferous forests,rocky shorelines and sand dunes. The coastal wetlandecosystems of the Great Lakes include about 30,000

islands, bogs, fens, coastal marshes, coastal ridges andswales, shrub swamps, wet prairies, forested wetlandsand alvars. Only a small percentage of the original extentof wetlands remains around the Great Lakes after over200 years of intensive development and urbanization(Mitsch and Wang 2000).

For the rst time this study included wetlands inthe coastal watersheds of Washington, Oregon andCalifornia. These three states have 1,290 miles ofshoreline extending from Puget Sound to the California Mexico border, with more than 410 estuaries and bays(USEPA 2012). The Pacic coast lacks the extensivecoastal plain found elsewhere in the U.S. and instead ischaracterized by steep topographic relief between land

and sea. As a result, saltwater marshes and estuarineats are found only in discontinuous segments. Intertidalwetlands are located principally in coastal embaymentssuch as Grays Harbor, Willapa Bay and Puget Soundin Washington; the Columbia River Estuary, Coos Bay,Tillamook Bay and Yaquina Bay in Oregon; andHumboldt Bay, San Francisco Bay, Bolsa Chica Bayand the Tijuana Estuary in California. Since the 1850s90 percent of Californias original coastal wetlandacreage has disappeared, and many of the remainingwetlands are in danger of being further degraded ordestroyed due to lling, diking, dredging, pollution andother human disturbances (CA Natural Resources Agency2013). The coastal areas of Oregon and Washingtonare somewhat less degraded than those of California,but dams and other water diversions affect the timing,quantity and quality of freshwater ows down rivers andinto estuaries (Gleason et al.2011).

Study Area 11

Freshwater wetland on Madeline Island, Wisconsin.

Figure 8. Coastal Watersheds of the

Conterminous United States (shown in

darker green) as used in this study.


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Study Methods


In the previous study by Stedman and Dahl (2008), andin the present study analysis of the USFWS NationalWetlands Status and Trends dataset was conducted toprovide updated information specically on the statusand extent of wetland resources in the coastal watershedsand the recent changes that had occurred. Randomlyselected plots were assessed using digital high-resolutionimagery to identify change in wetlands, deepwaterhabitats and uplands. Imagery used to detect changesincluded digital high resolution (


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Habitat Definitions 13

Habitat Definitions

During the mid-1970s USFWS began work on abiological denition of wetland and standardizednomenclature for the classication of wetland types. Thissystem described by Cowardin et al.(1979), was adoptedas a standard by USFWS and subsequently became aFederal Geographic Data Committee (FGDC) Standardfor mapping, monitoring and reporting on wetlands(FGDC 1996). This institutionalization of a biologicaldenition and classication system has facilitated itsuse in numerous Federal applications and has providedconsistency and continuity by dening the biologicalextent of wetlands and common descriptors for wetlandtypes. It is a two-part denition as indicated below:

Wetlands are lands transitional betweenterrestrial and aquatic systems where the watertable is usually at or near the surface or the landis covered by shallow water.

For purposes of this classification wetlandsmust have one or more of the following threeattributes: (1) at least periodically, the landsupports predominantly hydrophytes, (2) thesubstrate is predominantly undrained hydric soil,and (3) the substrate is nonsoil and is saturatedwith water or covered by shallow water at some

time during the growing season of each year.

Cowardin et al.(1979) and other researchers (Gosselinkand Turner 1978; Mitsch and Gosselink 1993) recognizedthat hydrology was universally regarded as the mostbasic feature of wetlands and that hydrology, not thepresence of vegetation, determines the existence ofwetland (Cowardin and Golet 1995). For this reason,in areas that lack vegetation or soils (e.g. coastal mudats, sand beaches, rocky bars and shorelines) hydrologydetermines that these areas are wetlands. In practice,three indicators - hydrophytic vegetation, undrainedhydric soil, and wetland hydrology; two indicators- hydrophytic vegetation and wetland hydrology orundrained hydric soil and wetland hydrology; or a singleindicator - wetland hydrology, may be used to identifywetland based on the conditions at any particular site(FGDC 2013).

Cowardin et al.(1979) dened estuarine and marinewetlands as saltwater systems; consequently no estuarineor marine wetlands were identied in the coastal

watersheds of the Great Lakes portion of this study.Shoreline wetlands of the Great Lakes were includedwith other freshwater wetlands in the Great Lakes coastalwatersheds.

Ephemeral waters, which are not recognized as a wetlandtype, and certain types of farmed wetlands as denedby the Food Security Act were not included in this studybecause they do not meet the Cowardin et al.denition.Habitat category denitions used in this study are givenin synoptic form in Table 2. Complete denitions ofwetland types and land use categories used in this studyare provided in Appendix A.

Wetlands and deepwater habitats are dened separatelyby Cowardin et al.(1979) because the term wetland doesnot include deep, permanent water bodies. Deepwaterhabitats are permanently ooded land lying below thedeepwater boundary of wetlands. Deepwater habitatsinclude environments where surface water is permanentand often deep, so that water, rather than air, is theprincipal medium in which the dominant organismslive, whether or not they are attached to the substrate.For the purposes of conducting status and trends work,all lacustrine (lake) and riverine (river) waters as wellas deep, open water estuaries and marine waters were

considered deepwater habitats.

Upland included lands not meeting the denition ofeither wetland or deepwater habitats. An abbreviatedupland classication system patterned after theU. S. Geological Survey land classication schemedescribed by Anderson et al.(1976), with ve generalizedcategories, was used to describe uplands in this study.

Blue Crab (Callinectes sapidus), Monroe County, Florida


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Study Limitations

The identication and delineation of wetland habitatsthrough image analysis formed the foundation forderiving the wetland status and trends data resultsreported here. Because of the limitations of aerial imageryas the primary data source to detect some wetlands,certain wetland types were excluded from study. Theselimitations included the inability to detect small wetlandareas; inability to accurately detect or monitor certaintypes of wetlands such as seagrasses that may requirehyperspectral or other specialized imagery or analysistechniques (Dierssen et al.2003; Peneva et al.2008),submerged aquatic vegetation, or submerged reefs (Dahl2005); and inability to consistently identify certain

forested wetlands either because of their small size,canopy closure, or lack of visible hydrology.

Freshwater wetland, Weeks Bay, Alabama

Table 2. Wetland, deepwater, and upland categories used to conduct this study. The definitions for

each category appear in the Appendix.

Saltwater Habitats Common Description

Marine Subtidal* Open ocean

Marine Intertidal Near shore

Estuarine Subtidal* Open-water/bay bottomsEstuarine Intertidal Emergents Salt marsh

Estuarine Intertidal Forested/Shrub Mangroves or other estuarine shrubs

Estuarine Intertidal Unconsolidated Shore Beaches/bars/shoals

Riverine* (may be tidal or non-tidal) River systems

Freshwater Habitats

Palustrine Forested Forested swamps

Palustrine Shrub Shrub wetlands

Palustrine Emergents Inland marshes/wet meadows

Palustrine Unconsolidated Bottom (ponds) Open-water ponds/aquatic bed

Lacustrine* Lakes and reservoirs

Uplands

Agriculture Cropland, pasture, managed rangeland

Urban Cities and incorporated developments

Silviculture Planted or intensively managed forests; silviculture

Rural Development Non-urban developed areas and infrastructure

Other Uplands Rural uplands not in any other category barren lands*Constitutes deepwater habitat



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Freshwater wetlands, Big Pine Key, Florida

Study Limitations 15

Coastal marsh, Pettaquamscutt Cove, Rhode Island


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Results: Status of Wetlands in Coastal Watersheds, 2009

In 2009, there were an estimated 41.1 million acres of

wetlands in the coastal watersheds of the United States.13This area represented 37.3 percent of total wetland area inthe conterminous U.S. Of the wetland area in the coastalwatersheds, an estimated 34.6 million acres (84.3 percent)were freshwater wetland types and 6.4 million acres(15.7 percent) were saltwater as shown in Figure 9.

Saltwater wetlands were composed of estuarine emergentmarshes, estuarine shrub wetlands and estuarine or marinenon-vegetated wetland areas such as beaches, shoals,mud ats, coastal spits and sand bars. Estuarine emergentmarshes were found to be the most prevalent saltwaterwetland type making up an estimated 66.2 percent of all

saltwater wetlands. Estuarine shrub wetlands and non-vegetated saltwater wetlands comprised an estimated12.4 percent and 21.3 percent by area, respectively, in2009.

Freshwater wetlands were found in each of the coastalwatershed regions and made up an estimated 84 percentof the total wetland area of these watersheds in 2009.Freshwater wetlands were least prevalent in the Pacicwatersheds and most abundant in the watersheds of theAtlantic. There were an estimated 20.8 million acres offorested wetland (this represented 60.2 percent of thearea of all freshwater wetlands in the coastal watersheds).

Freshwater shrub wetland area was estimated to havebeen 6.7 million acres (19.4 percent) with an estimated5.9 million acres (17.1 percent) of freshwater emergentmarshes and 1.2 million acres (3.3 percent) of freshwaterponds in 2009.

The watersheds of the Atlantic and Gulf of Mexico havevery similar amounts of wetland area (15.9 million and15.4 million acres, respectively) with the Atlantic coastlinehaving an estimated 460,000 acres more than the Gulf ofMexico. Watersheds of the Great Lakes had an estimated8.5 million acres of wetland. The Pacic coastal watershedshad the least amount of wetland with an estimated1.3 million acres. The percent of wetland area for each ofthe coastal regions in shown in Figure 10.

The distribution and relative wetland density of wetlandswithin the coastal watersheds in this study are shown inFigure 11.

13Stedman and Dahl (2008) found 39.8 million acres of wetlands in thecoastal watersheds. This study includes the additional coastal watershedarea of the Pacic coast in Washington, Oregon and California.

Freshwater

wetland area

Saltwa

wetland

84.3%

15.7%

Wetland Density

02%

34%

58%

912%

1315%

1625%



27/58

05%

610%

1115%

1625%

2640%

>40%

Wetland Density

Atlantic

20.7%

37.5%

38.7%

3.1%

Gulf of Mexico

Great Lakes

Pacific

Results 17

Figure 9. (Far left) Freshwater and saltwater wetland by

area in the coastal watersheds (Atlantic, Gulf of Mexico,Great Lakes and Pacific), 2009.

Figure 10. (Left) Percent of all coastal wetland area by

coastal region, 2009.

Figure 11. Relative wetland density of the coastal

watersheds along the Atlantic, Gulf of Mexico, Great

Lakes and Pacific as determined by this study, 2009


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All saltwater (intertidal) wetlands in the conterminousU.S. (6.4 million acres) are located in the coastalwatersheds. The distribution of saltwater wetlandarea in the coastal watersheds of the Atlantic, Gulf ofMexico and Pacic14is shown in Figure 12. The coastalwatersheds along the Gulf of Mexico had the largestsaltwater wetland area in 2009 with 3.4 million acres.The Atlantic had an estimated 2.4 million acres and thePacic slightly over 700,000 acres. There were fewer

wetlands along the Pacic coast of Washington, Oregonand California as these coastlines are characterized by rockoutcrops, and less extensive areas of coastal plain (Figure 13).

Coastal watersheds of each coastal region alsosupport considerable freshwater wetland types. Anestimated 33.2 percent of all freshwater wetland areain the conterminous U.S. (Table 3) is located in thesecoastal watersheds. The Atlantic watersheds had thehighest percentage with about 13.5 million acres offreshwater wetland. The Gulf of Mexico had slightly over12 million acres and the Great Lakes had 8.5 million acres.The Pacic coastal watersheds had the least amount of

freshwater wetland area with an estimated 556,000 acres(Figure 14).

14Because Cowardin et al.(1979) denes marine and estuarinewetlands as saltwater systems, no estuarine or marine wetlands wereidentied in the coastal watersheds of the Great Lakes portion of this

study. All wetlands of the Great Lakes watersheds were freshwaterwetlands.

Table 3. Estimated freshwater wetland area in the coastal watersheds of the Atlantic, Gulf of Mexico, Great Lakes and Pacific as

compared to the conterminous United States, 2009. The coefficient of variation (CV) for each entry (expressed as a percentage) is

given in parentheses.

Wetland Category

Area in Acres

Wetland in Coastal Watersheds,2009

Wetland in Conterminous U.S.,2009

Percent Wetland Area in CoastalWatersheds, 2009

Freshwater Non-vegetated(ponds)1

1,145,503 6,709,300 17.1%

(4.5) (4.5)

Freshwater Forested 20,838,893 51,623,300 40.4%

(3.2) (2.7)

Freshwater Shrub 6,713,742 18,511,500 36.3%

(5.7) (4.2)

Freshwater Emergent 5,922,215 27,430,500 21.6%

(5.9) (7.6)

Freshwater Vegetated2 33,474,851 97,565,300 34.3%

(2.8) (2.9)

All Freshwater Wetlands 34,620,353 104,274,600 33.2%

(2.7) (2.8)

1Includes the category: Palustrine Unconsolidated Bottom.

2Includes the categories: Palustrine Forested, Palustrine Shrub and Palustrine Emergent.



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(52%)

(37%)

(11%)

3,349,800

2,377,700

713,800

Gulf of Mexico

Atlantic

Pacific

Great Lakes

Figure 12. Saltwater (intertidal) wetland distribution

(area in acres) by coastal regions, 2009.

(34.8%)

(39%)

(1.6%)

12,061,700

13,490,900

555,700

8,512,100(24.6%)

Figure 14. Freshwater wetland distribution (area in

acres) by coastal regions, 2009.

Results: Staus of Wetlands in Coastal Watersheds, 2009 19

Figure 13. Rocky shoreline along the coast of California.


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Changes in Wetlands of the Coastal Watersheds, 2004 to 2009

The estimated wetland area and changes for the coastalwatersheds of the Atlantic, Gulf of Mexico, Great Lakesand Pacic from 2004 to 2009 are presented in Table 4.Differences between the 2004 estimates of all wetlandsin coastal watersheds in this study as compared toestimates for the same time period reported by Stedmanand Dahl (2008) were due to the addition of the Paciccoast wetland area that was not included previously.15Collectively, saltwater and freshwater wetland areadeclined by an estimated 360,720 acres between 2004and 2009. The average annual rate of change for allwetlands in the coastal watersheds was a loss of 80,160acres over the period of this study. This was a 25 percent

increase in the rate of coastal wetland loss reported forthe period between 1998 and 2004.

The Atlantic, Gulf of Mexico and Pacic coastal regionsexperienced net wetland losses of 111,960 acres,257,150 acres and 5,220 acres, respectively. Thewatersheds of the Great Lakes region experienced a net

gain in wetland area of an estimated 13,610 acres. Seventyone percent of the estimated wetland losses between 2004and 2009 were in the coastal watersheds of the Gulf ofMexico.

There was an estimated net loss of 95,000 acresof saltwater wetlands. Modest gains in marine andestuarine non-vegetated wetland (ats, shoals and bars)were overshadowed by losses of estuarine vegetatedwetlands which declined by 2.4 percent (Table 5). Mostof the vegetated estuarine losses were to open saltwater(deepwater habitats) and virtually all of these lossesoccurred in the Gulf of Mexico.

Freshwater wetlands overall, experienced a net loss ofmore than 265,000 acres. Freshwater pond area increasedby almost six percent and freshwater emergent marshesand shrub wetlands also increased in area. However,freshwater forested wetlands declined by 405,700 acresresulting in a net loss of freshwater vegetated wetland areaof 328,800 acres (1.0 percent) between 2004 and 2009.

Changes to wetland area between 2004 and 2009 bycoastal region are graphically displayed in Figure 15.

15When normalized the difference in the estimated total wetlandarea for 2004 between the two studies is


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Table 4. Changes in wetland area for the coastal watersheds of the Atlantic, Gulf of

Changes in the Wetlands of the Coastal Watersheds 21

Mexico, Great Lakes and Pacific, 2004 to 2009.

Coastal RegionWetland Area 2004

(acres)Wetland Area 2009

(acres)Net Change

(acres)PercentChange

Atlantic 15,980,550 15,868,594 -111,957 -0.7 %

Gulf of Mexico 15,668,626 15,411,472 -257,153 -1.6 %Great Lakes 8,498,448 8,512,056 13,608 +0.2 %

Pacic 1,274,725 1,269,504 -5,221 -0.4 %

Total 41,422,348 41,061,625 -360,723 -0.9 %

*

Table 5. Estimated status and change in wetland area for selected categories in the coastal watersheds of the Atlantic, Gulf of

Mexico, Great Lakes and Pacific, 2004 to 2009. The coefficient of variation (CV) for each entry (expressed as a percentage) is given

in parentheses.

Wetland Category Area in AcresEstimated Area, 2004 Estimated Area, 2009 Change, 2004 to 2009 Change (percent)

Marine Intertidal 231,221 239,658 8,437 3.6%

(15.2) (14.8) (50.1)

Estuarine IntertidalNon-vegetated1

1,114,614 1,135,468 20,854 1.9%

(12.9) (12.7) (44.3)

Estuarine IntertidalVegetated2

5,190,437 5,066,146 -124,290 -2.4%

(4.5) (4.5) (17.2)

All Intertidal (Saltwater)Wetlands

6,536,271 6,441,272 -94,999 -1.5%

(4.5) (4.5) (21.1)

Freshwater

Non-vegetated31,082,424 1,145,503 63,079 5.8%

(4.6) (4.5) (23.3)

Freshwater Forested 21,244,634 20,838,893 -405,741 -1.9%

(3.2) (3.2) (19.6)

Freshwater Shrub 6,657,614 6,713,742 56,128 0.8%

(5.7) (5.7) (*)

Freshwater Emergent 5,901,405 5,922,215 20,811 0.4%

(5.9) (5.9) (*)

Freshwater VegetatedWetlands4

33,803,653 33,474,851 -328,802 -1.0%

(2.7) (2.8) (19.6)

All Freshwater Wetlands 34,886,077 34,620,353 -265,723 -0.8%

(2.6) (2.7) (23.8)All Wetlands 41,422,349 41,061,625 -360,723 -0.9%

(2.3) (2.3) (19.0)

Statistically unreliable

1Includes the category: Estuarine Intertidal Unconsolidated Shore

2Includes the categories: Estuarine Intertidal Emergent and Estuarine Intertidal Shrub

3Includes the categories: Palustrine Unconsolidated Bottom

4Includes the categories: Palustrine Emergent, Palustrine Forested and Palustrine Shrub.


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Trends in Saltwater Wetlands, 2004 to 2009

The majority of saltwater (estuarine and marine) wetlandsfall into three types: estuarine intertidal emergentwetlands (salt and brackish water marshes), estuarineshrub wetlands (mangrove swamps and other salt-tolerantwoody species), and marine or estuarine intertidal non-vegetated wetlands. The latter category included exposedcoastal beaches subject to tidal ooding, as well as sandbars, tidal mud ats, shoals and sand spits.

There were an estimated 6,441,300 acres of saltwaterwetlands in the conterminous U.S. in 2009. Non-vegetated wetland types experienced considerableamount of change related to the constantly changing

shape of the coastline. Estuarine vegetated wetlandsexperienced a decline of 124,300 acres between 2004and 2009. As was seen in the earlier study covering 1998to 2004, loss to open saltwater was responsible for themajority of these losses (Figure 16).

Saltwater wetland (vegetated and non-vegetated) areadeclined by an estimated 1.5 percent. This representeda 35 percent increase over the rate of saltwater wetlandloss reported by Stedman and Dahl (2008) for the periodbetween 1998 and 2004. The increased loss rate wasattributed to accelerated losses in the Gulf of Mexicowhere the estimated rate of saltwater wetland loss morethan doubled from 44,800 acres between 1998 and 2004to 95,300 acres between 2004 and 2009 (Figure 17).These losses accounted for 99 percent of all saltwaterwetland losses to open deepwater between 2004 and2009. Saltwater wetland losses in the Gulf of Mexicohave been attributed to the effects of severe coastal

storms16such as Hurricanes Katrina and Rita in 2005 andHurricane Ike in 2008, which inundated wetlands withstorm surge, abnormally high tides, increased rainfall,runoff, increased sediment and debris deposition and

16Coastal storms include tropical storms, hurricanes and winterstorms.

FreshwaterWetlands

UplandDevelopment

OtherUplands

OpenSaltwater

20,000

-40,000

-120,000

-100,000

-80,000

-60,000

0

Acres

-20,000


Figure 16. Attribution of loss or conversion of saltwater wetlands in the coastal watersheds of the Atlantic, Gulf of Mexico and

Pacific, 2004 to 2009


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Acres

0100

101300

301700

7012500

25014510

TEXAS

LOUISIANA MISSISSIPPIALABAMA

FLORIDA

Trends in Saltwater Wetlands 23

Figure 17. Coastal watersheds of the upper Gulf of Mexico showing the magnitude of saltwater (intertidal) wetland loss to open water, 2004

to 2009.

erosion. Considerable losses of wetland area resultedfrom Hurricane Katrina alone (Costanza et al.2006).By comparison, a small percentage of saltwater wetlandlosses have been traced to discrete anthropogenicactions17in the Gulf of Mexico.

In contrast, the coastal watersheds of the Atlanticexperienced a small net gain of about 330 acres(


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Table 6. Estimated changes to saltwater (intertidal) wetlands of the Atlantic (A), Gulf of Mexico (B) and Pacific (C)

coastal watersheds, 2004 to 2009. (The Coefficient of Variation [CV] for each entry is given in the parentheses.)

A. Estimated Changes to Saltwater Wetlands of the Atlantic Coast

Wetland CategoryArea in Acres

Estimated Area, 2004 Estimated Area, 2009 Change, 2004 to 2009 Change (percent)


(23.4) (23.2) (*)


302,473 304,684 2,211 0.7%

(17.5) (17.4) (98.5)

Estuarine Emergent 1,846,327 1,838,965 -7,362 -0.4%

(6.8) (6.8) (61.9)

Estuarine Shrub 122,037 126,433 4,397 3.6%

(15.3) (15.1) (73.9)


1,968,363 1,965,398 -2,965 -0.2%

(6.5) (6.5) (*)


2,377,362 2,377,691 329 0.0%

(6.5) (6.4) (*)

B. Estimated Changes to Saltwater Wetlands of the Gulf of Mexico Coast




(35.5) (30.7) (52.3)


406,222 424,865 18,643 4.6%

(13.9) (13.3) (48.1)

Estuarine Emergent 2,332,470 2,211,674 -120,796 -5.2%

(6) (6.1) (17.4)Estuarine Shrub 673,236 672,750 -486 -0.1%

(14.8) (14.6) (*)


3,005,706 2,884,424 -121,282 -4.0%

(5.7) (5.8) (17.3)


3,445,073 3,349,788 -95,285 -2.8%

(5.3) (5.4) (20.4)





*


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Trends in Saltwater Wetlands 25

Figure 18. Tidal saltmarsh in coastal Washington. This study found 30 percent of saltwater wetlands along in the Pacific coastal

watersheds were emergent saltmarsh.

Table 6. Estimated changes to saltwater (intertidal) wetlands of the Atlantic (A), Gulf of Mexico (B) and Pacific (C)

coastal watersheds, 2004 to 2009. (The Coefficient of Variation [CV] for each entry is given in the parentheses.)Continued

C. Estimated Changes to Saltwater Wetlands of the Pacific Coast



Marine Intertidal 91,549 91,549 0 0.0%

(23.9) (23.9) (0)


405,919 405,919 0 0.0%

(29.9) (29.9) (0)

Estuarine Emergent 216,313 216,269 -43 0.0%

(39.4) (39.4) (99)

Estuarine Shrub 55 55 0 0.0%

(98.7) (98.7) (0)


216,367 216,324 -43 0.0%

(39.4) (39.4) (99)


713,836 713,793 -43 0.0%

(24) (24) (99)




*


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Trends in Coastal Freshwater Wetlands, 2004 to 200

Overall, freshwater wetlands declined by an estimated265,720 acres (0.8 percent) between 2004 and 2009.Regionally, there was a small net loss (5,180 acres) alongthe Pacic, net losses of 112,290 acres along the Atlantic,large net losses (161,870 acres) along the Gulf of Mexicoand a modest net gain of 13,610 acres in the watershedsof the Great Lakes. The estimated changes to freshwaterwetland types by coastal region are shown on pages2829 in Table 7. There were gains in area of freshwatershrub wetlands, emergent wetlands, and ponds; howeverthese gains were offset by large losses of freshwaterforested wetlands (Figure 19).

Forested wetland area declined by an estimated405,740 acres between 2004 and 2009, a decreaseof 1.9 percent. Forested wetlands declined in each ofthe coastal watershed areas with the exception of theGreat Lakes. The greatest amount of change occurredin coastal watersheds from North Carolina to Florida

on the Atlantic, and Florida to Texas on the Gulf ofMexico, where forested wetland area declined by anestimated 443,780 acres between 2004 and 2009. Ofthis total change in forested wetland area, 63 percentof the acreage was cleared and converted to otherwetland types, such as freshwater shrubs. An estimated36 percent (158,340 acres) was lost to upland landuses. A comparatively small increase of an estimated47,940 acres of forested wetlands in the Great Lakesregion offset some of the large losses of forestedwetlands in the southeastern U.S. The estimated lossesof freshwater forested wetland in the coastal watershedsmade up over 64 percent of all forested losses in the

conterminous U.S. between 2004 and 2009; thus thecauses for those losses have far reaching implicationsfor wetland management, protection and regulationstrategies. The activities that converted forested wetlandto upland in the southeastern U.S. and the amount ofloss attributed to those activities are shown in Figure 20.

100,000

-100,000

-500,000

-400,000

-300,000

-200,000

0

Emergent Shrub Forested Ponds All FreshwaterTypes

Acres


Figure 19. Estimated losses and gains in area for the freshwater wetland types in the coastal watersheds of the Atlantic,

Gulf of Mexico, Great Lakes and Pacific, 2004 to 2009


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44.3%

39.1%

10.2%

6.1%

Development

Silviculture

Other Uplands

Agriculture

Figure 20. Forested wetland losses in the coastal watersheds of the Southeastern U.S. (North Carolina to Texas)

as attributed to upland land use categories, 2004 to 2009. Total forested wetland losses to upland in this region were

estimated to have been 158,340 acres over the years covered by this study.

Trends in Coastal Freshwater Wetlands 27

Freshwater forested wetland near Weeks Bay, Alabama.


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Table 7. Estimated changes to freshwater wetlands of the Atlantic (A), Gulf of Mexico (B), Great Lakes (C), and Pacific (D)

coastal watersheds, 2004 to 2009. (The Coefficient of Variation [CV] for each entry is given in the parentheses.)

A. Estimated Changes to Freshwater Wetlands of the Atlantic Coast




424,868 457,646 32,778 7.7%

(8.8) (8.4) (29.3)


(3.9) (3.9) (29.6)


(7.9) (8) (*)

Freshwater Emergent 1,862,415 1,906,028 43,614 2.3%

(10.3) (9.9) (83.9)Freshwater Vegetated2 13,178,320 13,033,256 -145,064 -1.1

(3.4) (3.4) (29.4)


(3.3) (3.3) (37.3)

All Wetlands3 15,980,550 15,868,594 -111,957 -0.7%

(2.9) (2.9) (37.3)

B. Estimated Changes to Freshwater Wetlands of the Gulf of Mexico Coast




376,721 407,641 30,919 8.2%

(6.5) (6.3) (30)


(5.1) (5.1) (19.3)


(9.6) (9.5) (77.3)

Freshwater Emergent 2,790,041 2,788,005 -2,035 -0.1%

(9.5) (9.4) (*)

Freshwater Vegetated2 11,846,831 11,654,043 -192,788 -1.6%

(4.1) (4.2) (24.3)


(4) (4) (28.6)

All Wetlands3 15,668,626 15,411,472 -257,153 -1.6%

(3.3) (3.3) (20.8)


Statistically unreliable1Includes the category: Palustrine Unconsolidated Bottom2Includes the categories: Palustrine Forested, Palustrine Shrub and Palustrine Emergent3Includes all freshwater and saltwater wetlands

*


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Table 7. Estimated changes to freshwater wetlands of the Atlantic (A), Gulf of Mexico (B), Great Lakes (C), and Pacific (D)

coastal watersheds, 2004 to 2009. (The Coefficient of Variation [CV] for each entry is given in the parentheses.) Continued

C. Estimated Changes to Freshwater Wetlands of the Great Lakes Coast




230,418 229,254 -1,163 -0.5%

(9) (9.6) (*)

Freshwater Forested 5,066,597 5,114,536 47,940 0.9%

(9.2) (9.1) (41.3)

Freshwater Shrub 2,191,113 2,174,479 -16,635 -0.8%

(12.3) (12.3) (*)

Freshwater Emergent 1,010,320 993,787 -16,534 -1.6%

(11.7) (11.9) (93.3)

Freshwater Vegetated2 8,268,030 8,282,802 14,771 0.2%

(7.7) (7.7) (73)

All Freshwater Wetlands 8,498,448 8,512,056 13,608 0.2%

(7.5) (7.5) (74.5)

All Wetlands3 8,498,448 8,512,056 13,608 0.2%

(7.5) (7.5) (74.5)

D. Estimated Changes to Freshwater Wetlands of the Pacific Coast


Estimated Area, 2004 Estimated Area,2009 Change, 2004 to 2009 Change(percent)


50,417 50,961 544 1.1%

(12) (12.3) (*)

Freshwater Forested 158,150 157,085 -1,064 -0.7%

(27.8) (28) (46.9)

Freshwater Shrub 113,693 113,269 -424 -0.4%

(23.1) (23.2) (*)

Freshwater Emergent 238,629 234,395 -4,234 -1.8%

(22.6) (23) (65)

Freshwater Vegetated2 510,472 504,750 -5,722 -1.1%

(15.9) (16.1) (53.7)

All Freshwater Wetlands 560,889 555,711 -5,178 -0.9%

(14.7) (14.8) (59)

All Wetlands3 1,274,725 1,269,504 -5,221 -0.4%

(15.5) (15.5) (58.5)

Statistically unreliable1Includes the category: Palustrine Unconsolidated Bottom2Includes the categories: Palustrine Forested, Palustrine Shrub and Palustrine Emergent3Includes all freshwater and saltwater wetlands


*


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Although there was an overall increase in freshwateremergent wetland area, emergent marshes declinedalong every coastline with the exception of the Atlantic

where there was a net gain of an estimated 43,610 acres.The majority of this increase was attributed to thereestablishment of emergent wetlands in areas formerlyclassied as upland agriculture, other conservationpractices or land retirement.

Freshwater shrubs exhibited an increase of 56,120 acresin the conterminous U.S. Freshwater shrub wetlandsdeclined in the coastal watersheds of the Pacic andGreat Lakes but increased in the coastal watersheds of theAtlantic and Gulf of Mexico. Freshwater shrub wetland

area increased as freshwater forests in the southeasternU.S. were cleared and the areas were reclassied asshrub wetlands.

Freshwater ponds increased in area by an estimated5.8 percent between 2004 and 2009. Urban pondsincreased in area by 19 percent or 55,700 acres whilenatural ponds declined in area by 3.9 percent or16,400 acres. The vast majority of these new ponds(99 percent) were constructed in the watersheds of theAtlantic and Gulf of Mexico and many were locatedin urban or suburban developments as likely waterdetention or ornamental ponds as opposed to targetedwetland reestablishment projects (Figure 21).


Figure 21. This aerial image shows the proliferation of freshwater ponds in a south Florida coastal watershed overtaken by development.

Many vegetated wetlands have been replaced by artificially created, open water ponds (darker areas).


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Overall, the largest land use associated with freshwaterwetland loss in coastal watersheds was silviculture,followed by development (both urban and rural),

which together account for 84 percent of the wetlandloss. Freshwater wetland loss to deepwater habitats or

saltwater wetlands is a smaller percentage of the total loss(16 percent), and a small amount of freshwater wetlandswere gained from agricultural lands and other uplands.

The loss or conversion of all freshwater wetlands from2004 to 2009 is shown in Figure 22.

100,000

50,000

-200,000

-150,000

-100,000

-50,000

0

Acres

Deepwater IntertidalWetlands

Agriculture OtherUplands

Silviculture Urbanand Rural

Development


Figure 22. Attribution of loss or conversion of freshwater wetlands in the coastal watersheds, 2004 to 2009.


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Discussion

Similar to the previous coastal wetland study conductedby Stedman and Dahl (2008), the majority of theestimated wetland losses in coastal watersheds between2004 and 2009 occurred in the freshwater system andwere attributed to different types of human activitythat converted wetlands to uplands. Understandingthe underlying cause(s) of these losses is important,particularly as they relate to efforts to adjust policy ormanagement strategies to reverse this trend. Based onthis study, the following issues appear to be central tounderstanding the ongoing loss of wetlands in coastalwatersheds.

Lack of Reestablishment of

Wetlands in Coastal Watersheds

Past studies of wetlands in the conterminous UnitedStates have documented losses that total about half of thewetland acreage that existed pre-European colonization(Dahl 1990). The Clean Water Act of 1977 (CWA) 20andother federal and state laws protecting wetlands havedecreased losses, and reestablishment programs havereversed some losses. For the Nation as a whole, therehas been a marked decrease in the overall rate of wetland

loss since 1998. One of the federal strategies to helpreduce wetland losses has been to promote and enablewetland reestablishment and creation projects. Thisstrategy has enjoyed some success and some wetlandlosses have been offset by wetland reestablishment,especially in agricultural areas (Dahl 2011).

Results from this study indicated that some wetlandlosses in coastal watersheds were being offset by wetlandreestablishment and creation projects. For example,there were net gains in freshwater wetland area fromagricultural lands (50,230 acres) and lands classiedas other uplands (15,290 acres) (Figure 23). Coastal

wetland gains occurred through reestablishment projects,changes in coastal geomorphology and in responseto changing hydrology. Wetland reestablishment asmeasured by the conversion from upland to wetland21

was most prevalent on agricultural lands primarily inthe coastal watersheds of South Carolina, Georgia andthe upper reaches of the watersheds in central Floridaand in the watersheds of the Great Lakes. In the GreatLakes watersheds historical conversion of wetlands toagricultural land uses through ditching and draining(Miller et al.2012) has provided ample possibilities forwetland reestablishment.

However, the strategy of offsetting wetland losses withwetland reestablishment and creation does not appearto be as effective in coastal watersheds as it has beennationally. Wetland losses in coastal watersheds have

continued to outdistance wetland gains, by an estimated360,720 acres between 2004 and 2009. This rate of lossincreased by 25 percent since the previous reportingperiod of 1998 to 2004,22and these continued losses ofwetlands have direct costs for people and longer-termresource implications for sh, wildlife and other naturalresources.

Several factors are likely responsible for wetlandreestablishment in coastal watersheds lagging behindreestablishment rates nationally, including the logisticaldifculties of working in coastal ecosystems, competingland use interests and higher costs to reestablish coastal

wetlands (Stedman and Dahl 2008). The reestablishmentof intertidal wetlands poses unique challenges related totheir complex linkages to terrestrial and marine habitats(Atkinson 2003). Sustainable wetland reestablishmentopportunities in coastal watersheds are further limited bygeography, human encroachment, land-use resulting infewer suitable sites, geophysical processes from the seathat hamper reestablishment efforts (i.e. coastal storms,sea level rise, erosion and subsidence) and the amount ofhistoric wetland area available for reestablishment. Somecoastal watersheds have been developed to a point wherewetland reestablishment or mitigation opportunities maybe very limited given the changes in regional hydrologyor the current land use. These changes reduce thechances for successful implementation of a watershed-based approach for compensatory mitigation of wetlandlosses.

20The Clean Water Act of 1977 [P.L. 95217] (U.S. Army Corps ofEngineers 1987)

21 Emergent wetlands typify wetland reestablishment projects.

22Some of these increased losses were due to the addition of thePacic coastal watersheds which contributed about 1,160 acres per yearto the overall wetland loss rate.


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33

Figure 23. The term Other lands has been used to describe land in transition

when it was not possible to categorize a distinguishable land use (e.g. urban or

agriculture). In this photograph, a coastal freshwater wetland has been filled

(loss in area) but the land use could not be determined (Louisiana, 2009).

Wetland Gains and Loss Examples on Other Lands (Undetermined Land Use)

This study found an estimated 15,290 acre net increase in freshwater wetland came from uplands

classified as other lands or lands with undetermined land use.

Other lands have included areas such as prairie, unmanaged or non-patterned upland forests,

scrub lands, barren and abandoned land, lands enrolled in set-aside programs, conservation

easement or other lands designated as wildlife management areas. Lands in transition may also

fit into this category when land has been cleared but not yet developed to the point of a

distinguishable land use (Figure 23).


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Tidal salt marsh, Washington


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Losses to Development

Of the estimated freshwater wetland losses to upland,urban and rural development accounted for an estimated

97,800 acres or 37 percent (Figure 24). Urban and ruraldevelopment was an important factor in wetland lossin coastal watersheds during the previous time period(1998-2004) as well (Stedman and Dahl, 2008). Coastaldevelopment has been identied by local stakeholdersas a serious threat to coastal wetlands due to the directand indirect effects of residential and commercialdevelopment, associated recreational developmentand expansion of supporting infrastructure includingroads, bridges and utilities (USEPA 2013a). There isgeneral recognition that once wetlands are lost throughdevelopment, the loss of their functions and valuesis often irreversible (Mitsch and Gosselink 2000).

Recognizing the potential for degradation of the Nationswaters, the U.S. Congress enacted the CWA to maintainand restore the chemical, physical and biologicalintegrity of the waters of the United States. Section 404

of the Act requires avoidance and minimization ofimpacts to aquatic resources, including wetlands, and

requires compensatory mitigation to offset losses thatresult from authorized development. Development canand does occur without authorization or in wetlandsnot under CWA jurisdiction. An area considered to be awetland under the Cowardin classication system mayor may not be a wetland under jurisdiction or it may beexempt from protection under the CWA for a number ofreasons including how wetlands are delineated per theArmy Corps of Engineers Wetland Delineation Manual(U.S. Army Corps of Engineers 1987) or recent SupremeCourt rulings that have limited the CWAs jurisdiction.The CWA has undoubtedly reduced the loss of coastalwetlands to development, but not eliminated it.

Some states have implemented wetland regulatoryprograms governed by rules and/or state statutes that mayextend protection beyond the jurisdiction of the CWA.

Discussion 35

Figure 24. A residential housing development built on filled wetland in the upper portion of a coastal watershed in Louisiana.


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Forested Wetlands and Silviculture

This study found that forested wetland area declined byan estimated 443,780 acres in the coastal watersheds of

the southeastern U.S. between 2004 and 2009. Of thistotal change in forested wetland area, 63 percent of theacreage was cleared and converted to other wetlandtypes, but was not considered a wetland loss, and anestimated 36 percent (158,340 acres) was lost to uplandland uses. Of the forested wetland area lost to upland,an estimated 44 percent or 69,700 acres were attributedto silvicultural practices in the southeastern coastalwatersheds. Other studies have also reported substantialchanges to wetlands due to silviculture practices (USEPA2013a; Swords 2012; Dahl 2011; 1999; NCSU 2008).

Harvesting or the removal of trees from forested wetlandsdoes not, in itself, constitute a wetland loss.23However,

some activities associated with forested plantationsinvolve drainage ditching, intensive site preparations,timber stand management and harvest practices thatcan alter or eliminate site hydrology, thereby causinga loss of wetland. Under Section 404 of the CWA apermit is not required for the discharge of dredged or llmaterial associated with normal silviculture activitiesor the construction of and maintenance of forest roads.However, the CWA and implementing reg

Status and Trends of Wetlands from 2004 to 2009

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