U.S. Fish & Wildlife Service

National Wetlands Inventory 

Wetlands Status and 

Trends Reports 

Wetlands Status and Trends 

reports provide science-based

information on the status of 

America’s wetlands through

time. 

Project Overview 

Recognizing the importance of 

America’s wetlands, Congress enacted 

the Emergency Wetlands Resources 

Act (Public Law 99-645) of 1986. It 

requires the U.S. Fish and Wildlife 

Service (Service) to map wetlands in 

the United States, as well as conduct 

national status and trends studies 

and report to Congress every decade. 

These mandates are carried out by the 

Service’s National Wetlands Inventory 

Program (NWI), which provides 

foundational data for wetland science, 

management, and policy actions, from 

the individual wetland to the national 

scale. 

Five national Status and Trends 

reports and seven regional reports 

have been published to date (https:// 

www.fws.gov/wetlands/status-andtrends). The earliest national report 

addressed the status of America’s 

wetlands in the mid-1950s through 

mid-1970s, and the latest report covers 

the years 2004 through 2009. Regional 

reports build off national reports by 

focusing on areas within the United 

States that are experiencing relatively 

high rates of wetland loss. To date, two 

coastal watersheds, four state, and one 

prairie pothole regional report have 

been produced. Currently, data are 

being collected to produce the sixth 

national report to Congress, covering 

the years 2009 through 2019. The 

report is due for publication in 2022. 

Study Design 

More than 5,000 randomly distributed 

four square mile sample plots are 

assessed to support the national 

report. For each sample plot, imagery 

is analyzed for the beginning and end 

of the study period to assess land use 

and land cover. Field verifcation is 

then completed for a portion of the 

plots to ensure the accuracy of fndings. 

Any relevant changes in land use and 

land cover between the time periods are

recorded, and a statistical estimate 

Coastal wetland at St. Marks National Wildlife Refuge in Florida. 

Steve Hillebrand/USFWS 
USFWS 

of wetland and deepwater areas and 

change is calculated for the study area. 

The Status and Trends studies use a 

biological criterion for classifcation 

of wetlands (Cowardin et al. 1979), 

and collect data independent of land 

ownership. All major wetland types 

are examined in the study, including 

freshwater (palustrine) and saltwater 

(marine or estuarine) wetlands. 

Wetland types are further divided 

into nine subcategories, including 

freshwater forested, estuarine 

intertidal emergent, and marine 

intertidal. Data are also collected 

on lacustrine, marine, and estuarine 

deepwater habitats. 

These studies have high standards for 

data quality, and incorporate the latest 

technologies to enhance effciencies and 

decrease uncertainty. Improvements 

in the availability and spatial resolution 

of remotely sensed imagery, as well 

as other advancements, have enabled 

the Service to better monitor change. 

We subject our reports to expert peer 

review to ensure that the results meet 

the highest scientifc standards. 

Mapping Change 

Wetlands Status and Trends studies 

track changes in wetland area and type 

at the local level, and use statistical 

analysis to summarize this information 

at the regional or national scale. In 

the example to the right, we found 

high levels of wetland loss due to 

development in an area that was once 

dominated by wetlands (93 percent of 

total area). Examination of imagery 

from 1998 and 2004 in this area found a 

loss of 668 acres of freshwater wetlands 

within this six-year study period. An 

additional 290 acres of wetlands were 

lost between 2004 and 2009. 

These dramatic losses greatly reduce 

the important benefts that wetlands 

provide, such as water fltration and 

storage during foods, as well as habitat 

for fsh, wildlife, and plants. 

Conservation Results 

Wetlands Status and Trends reports 

have generated tremendous interest in 

wetland conservation and restoration. 

They have catalyzed policy actions 

that substantially slowed wetland 

loss. For example, the Swampbuster 

provision in the 1985 Farm Bill and 

the 1989 U.S. federal policy of “No 

Net Loss” of wetlands were greatly 

infuenced by the 1984 Status and 

Trends report, which found that 

Wetland Loss 

1998-2004 

2004-2009 

Approximately 93 percent of this 4-square-mile area was once vegetated wetland. This 

image indicates cumulative wetland losses due to development between 1998 and 2009. 

between the mid-1950s and 1970s 

there was a national net loss of wetland 

area equal to about twice the size 

of New Jersey. These U.S. federal 

wetland policy changes were partially 

responsible for the substantial decline 

in net wetland loss since the mid1900s. The Status and Trends reports 

continue to infuence wetland policy 

and management today by driving 

collaboration and cooperative planning 

between federal, state, and local 

partners. 

Informing Future Conservation 

Accurate, up-to-date information 

on wetland area and change is 

an invaluable conservation asset, 

supporting the adaptive management 

of wetlands and the benefts they 

provide the Nation, including those 

related to public health, safety, and 

recreation benefits. 

Within the Service, Wetlands Status 

and Trends reports are used to guide 

wetland restoration and enhancement 

projects, species habitat availability 

assessments, strategic habitat 

conservation planning, and ecosystem 

management activities. Recently, these 

data have been used in Species Status 

Assessments, helping to inform species 

listing decisions under the Endangered 

Species Act. The upcoming sixth 

national report will provide information 

on wetland gains and losses from 2009 

to 2019, further supporting America’s 

knowledge of, engagement in and 

informed decision-making around 

wetlands, wildlife, and natural resource 

management. 

Visit https://www.fws.gov/wetlands/ 

status-and-trends to learn more 

and access Status and Trends 

reports. For general questions, email 

wetlands_team@fws.gov. 

U. S. Fish and Wildlife Service 

Ecological Services 

5275 Leesburg Pike 

Falls Church, VA 22041 

703-358-2171 

www.fws.gov/ecological-services 

January 2020