Estuary habitat loss is visible in both recent national wetland trends and long historical declines. In the conterminous United States, coastal watersheds held an estimated 41.6 million acres of wetlands in 2019, but lost 191,000 acres between 2009 and 2019. The pattern varied sharply by region and habitat type, with some coastal areas gaining wetland area while saltwater vegetated habitats declined.
Contents
- The national coastal-wetland baseline
- Recent national losses and habitat shifts
- Regional patterns across coastal watersheds
- Saltwater and estuarine wetland change by coast
- Long-term West Coast and Gulf losses
- Local collapse and restoration responses
The national coastal-wetland baseline
The National Oceanic and Atmospheric Administration’s Status and Trends of Wetlands in the Coastal Watersheds of the Conterminous United States 2009 to 2019 provides the central national baseline. In 2019, coastal watersheds covered 13% of the conterminous United States by area but contained 36% of its wetlands. Their estimated wetland total was 41.6 million acres. NOAA, Status and Trends of Wetlands in the Coastal Watersheds of the Conterminous United States 2009 to 2019
Freshwater wetlands made up 85% of coastal-watershed wetlands in 2019. They were 96% vegetated and totaled 34.0 million acres. Saltwater wetlands were 79% vegetated and totaled 5.0 million acres. These figures describe the broader coastal-watershed system, not only the open-water channels of individual estuaries.
Saltwater habitat was divided among several distinct forms. Estuarine emergent salt marsh was the largest saltwater wetland type, covering 4.2 million acres in 2019. Saltwater non-vegetated areas, including mud flats, beaches, shoals and sand bars, covered 1.3 million acres. Saltwater forested and shrub wetlands covered 871,000 acres.
The same 2019 baseline shows the scale of the two largest regional wetland inventories. Atlantic coastal watersheds contained 16.0 million acres of wetlands, while Gulf of Mexico coastal watersheds contained 15.8 million acres.
Recent national losses and habitat shifts
Between 2009 and 2019, coastal watersheds experienced a net wetland loss of 191,000 acres. NOAA reported an approximate net loss rate of 18,190 acres per year for that period. Wetland area declined 0.5% in coastal watersheds, compared with 0.2% across the entire conterminous United States. Although coastal watersheds covered 13% of the country, they accounted for 86% of its net wetland losses during those years.
The net figure conceals movement between habitat categories. Vegetated wetlands declined by 314,000 acres, while non-vegetated wetlands increased by 133,000 acres. Deepwater categories increased by 87,000 acres. The resulting changes show why a stable-looking total in one category would not necessarily mean stable estuary habitat: vegetation, exposed wetland surfaces and deeper-water areas can shift in different directions.
Saltwater wetlands declined by a net 31,000 acres from 2009 to 2019. Saltwater vegetated wetlands declined by 68,000 acres, or 1.3%, while saltwater non-vegetated wetlands increased by 37,000 acres, or 2.8%. Estuarine emergent marsh declined by 74,000 acres, or 1.8%. All freshwater wetlands in coastal watersheds declined by 160,000 acres over the same period.
| Measure | Change, 2009–2019 |
|---|---|
| All coastal-watershed wetlands | -191,000 acres |
| Vegetated wetlands | -314,000 acres |
| Non-vegetated wetlands | +133,000 acres |
| Deepwater categories | +87,000 acres |
| Saltwater wetlands, net | -31,000 acres |
| Saltwater vegetated wetlands | -68,000 acres (-1.3%) |
| Saltwater non-vegetated wetlands | +37,000 acres (+2.8%) |
| Estuarine emergent marsh | -74,000 acres (-1.8%) |
| Freshwater wetlands | -160,000 acres |
All figures in this table are from NOAA’s 2009–2019 coastal-watershed assessment.
Regional patterns across coastal watersheds
The national decline was not evenly distributed. North Atlantic coastal watersheds gained 19,883 acres of wetlands, a 0.5% increase, between 2009 and 2019. Pacific coastal watersheds also gained 12,722 acres, or 0.9%. These gains occurred alongside losses in other regions.
South Atlantic coastal watersheds lost 77,546 acres, a 0.6% decrease. Gulf of Mexico coastal watersheds lost 113,557 acres, a 0.7% decrease. Great Lakes coastal watersheds lost 32,552 acres, a 0.4% decrease.
| Coastal-watershed region | Wetland change, 2009–2019 | Percentage change |
|---|---|---|
| North Atlantic | +19,883 acres | +0.5% |
| South Atlantic | -77,546 acres | -0.6% |
| Gulf of Mexico | -113,557 acres | -0.7% |
| Great Lakes | -32,552 acres | -0.4% |
| Pacific | +12,722 acres | +0.9% |
Earlier intervals show a faster rate of loss. Coastal watersheds lost an estimated 360,720 acres of saltwater and freshwater wetlands between 2004 and 2009, an average annual loss rate of 80,160 acres. Saltwater wetlands alone declined by more than 95,000 acres in that interval.
For the eastern United States, NOAA estimated a loss of 361,100 acres of wetlands between 1998 and 2004. Gulf of Mexico watersheds lost an estimated 397,000 acres of freshwater vegetated wetlands from 1998 to 2004. These historical estimates cover different periods from the 2009–2019 assessment and should not be treated as a single continuous annual series.
Saltwater and estuarine wetland change by coast
The coastal data distinguish saltwater non-vegetated wetlands from estuarine intertidal vegetated wetlands. That distinction matters because increases in exposed or non-vegetated areas occurred alongside losses in vegetated habitats.
In the North Atlantic from 2009 to 2019, saltwater non-vegetated wetlands increased by 10,165 acres, or 4.4%. Estuarine intertidal vegetated wetlands declined by 5,365 acres, or 0.7%. In the South Atlantic, saltwater non-vegetated wetlands increased by 3,498 acres, or 3.3%, while estuarine intertidal vegetated wetlands increased by 2,048 acres, or 0.2%.
Across the Atlantic, saltwater non-vegetated wetlands increased by 13,663 acres, or 4.0%. Atlantic estuarine intertidal vegetated wetlands declined by 3,317 acres, or 0.2%. The Atlantic-wide figures combine the North and South Atlantic regions and therefore should not replace their separate measurements.
The Gulf of Mexico recorded a different pattern. Saltwater non-vegetated wetlands increased by 18,500 acres, or 3.4%, but estuarine intertidal vegetated wetlands declined by 59,377 acres, or 2.0%. All Gulf of Mexico saltwater wetlands declined by 40,877 acres, or 1.2%, between 2009 and 2019.
Pacific estuarine intertidal vegetated wetlands declined by 5,434 acres, or 1.7%, in the same period. Taken together, these coast-specific statistics show that regional wetland gains do not necessarily represent recovery of vegetated estuarine habitat.
Long-term West Coast and Gulf losses
The historical record is substantially larger than the recent decade. NOAA’s feature on West Coast mapping reports that historical tidal wetlands in California, Oregon and Washington declined by about 85% after more than a century of development. West Coast estuaries historically covered nearly 2 million acres before the documented losses.
The mapping project estimated nearly 450 estuaries in the contiguous U.S. West Coast study area. Among the 55 larger West Coast estuaries with historic and current wetland data, about 85% of their original vegetated wetlands had been lost. Those 55 estuaries represented about 97% of the historical estuary area on the West Coast.
The losses varied by estuary. San Francisco Bay lost about 85% of its original vegetated tidal wetlands. The Columbia River estuary lost about 74% of its original vegetated tidal wetlands. These are historical comparisons to original extent, not measurements of loss during the 2009–2019 national assessment. NOAA, New Mapping Reveals Lost West Coast Estuary Habitat
Seagrass losses provide another long-term indicator. In the USGS Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002, all 14 estuarine systems assessed experienced some decline in seagrass habitat during 1940–2002. USGS, Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002
Local collapse and restoration responses
The Indian River Lagoon illustrates how a local estuary can combine a long-term habitat loss with a defined restoration program. NOAA describes the lagoon as a 156-mile-long estuary undergoing a system-wide restoration effort. Harmful algal blooms killed an estimated 89% of its seagrass between 2011 and 2020, and the lagoon has lost more than 140,000 acres of seagrass after years of degradation. NOAA, A System-Wide Effort to Restore Florida’s Indian River Lagoon
NOAA provided $9.4 million for 15 Indian River Lagoon restoration projects during 2023–2026. The restoration plan includes reconnecting 2,125 acres of wetlands and restoring 45 acres of seagrass. Those are planned or funded response measures for the period identified by NOAA, not completed habitat gains.
A national comparison also separates loss from restoration. The United States lost 139,552 acres of estuarine wetlands, equal to 2.5% of the 1996 area, between 1996 and 2010. Federally funded voluntary restoration covered 145,442 acres of estuarine wetlands between 2006 and 2015. These measurements come from NOAA’s Voluntary Restoration: Mitigation’s Silent Partner in the Quest to Reverse Coastal Wetland Loss in the USA. NOAA repository, Voluntary Restoration: Mitigation’s Silent Partner in the Quest to Reverse Coastal Wetland Loss in the USA
NOAA reported nearly 80,000 acres of U.S. coastal wetlands lost each year to development, draining, erosion and sinkage in a 2020 coastal-wetland infographic. The same infographic reported that NOAA and partners had restored nearly 50,000 acres of U.S. wetland habitat since 2008, as of 2020. NOAA, Infographic: Value of Coastal Wetland Habitat
At the estuary-program level, National Estuary Program partners reported more than 2.5 million acres restored or protected since 2000, reported in 2025. U.S. Environmental Protection Agency, National Results from the National Estuary Program