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Tidal Wetlands Abundance

As of 2010, there were approximately 282,291 acres of tidal wetlands in the Chesapeake Bay watershed’s estuarine drainage area. This marks an increase of 1,289 acres between 2005 and 2010, but a long-term loss of 1,566 acres between 1992 and 2010.

July 22, 2011

A team of wildlife professionals is on a mission to eradicate the destructive, invasive rodent nutria from the Chesapeake Bay’s marshes. Steve Kendrot, wildlife biologist with the USDA Animal and Plant Health Inspection Service (APHIS), leads us on a journey through an Eastern Shore marsh to find signs of nutria, and explains why it’s so important for local landowners to support the eradication project.


Healthy wetlands are vital to a healthy Chesapeake Bay. Located where land meets water, wetlands trap polluted runoff and slow of the flow of nutrients, sediment and chemical contaminants into rivers, streams and the Bay. By soaking up stormwater and dampening storm surges, wetlands slow the erosion of shorelines and protect properties from floods. Wetlands also provide critical habitat for fish, birds, mammals and invertebrates, and support recreational fishing and hunting across the watershed.

Shoreline development, sea level rise and invasive species pose the biggest threats to tidal wetlands. Development along beaches and shorelines blocks the formation of wetland habitat and sends excess sediment into the Bay. Sea level rise floods wetlands with saltwater, destroying plants faster than they can populate higher ground. And invasive plants and animals can crowd out native species or damage wetland habitat.

Chesapeake Bay Program partners will use this indicator to target management approaches toward those areas shown to be the most vulnerable to tidal wetland loss and conversion.


This indicator does not track progress toward a goal. Instead, it measures how many acres of tidal wetlands are in the Chesapeake Bay’s estuarine drainage area and identifies trends in abundance.

This indicator will inform partners’ work to achieve the wetlands outcome to create or reestablish 85,000 acres of wetlands and enhance the function of an additional 150,000 acres of degraded wetlands by 2025.

Assessment of the long-term data shows a declining trend in tidal wetland abundance, with a small rebound of 1,289 acres between 2005 and 2010, scattered throughout the watershed. According to land change statistics, the Chesapeake Bay’s estuarine drainage area lost 1,566 acres of tidal wetlands between 1992 and 2010. These changes are not significant on a Bay-wide scale.

Additional Information

This indicator is a quantitative tool that is not intended to speak to the quality or health of the wetlands being analyzed.


This indicator uses data from the National Oceanic and Atmospheric Administration’s Coastal Change Analysis Program (C-CAP) to determine the abundance of tidal wetlands in acres.

C-CAP produces a nationally standardized database of land cover and land change information for the coastal United States. C-CAP products include land cover maps and information about what land cover changes have taken place and where these changes were located. These products provide inventories of coastal intertidal areas, wetlands and adjacent uplands with the goal of monitoring these habitats by updating the land cover maps every five years.

This indicator will be improved over time. In the future, the Chesapeake Bay Program will be able to conduct high-resolution sampling verification of C-CAP data. In addition, NOAA is working to analyze data from 1984, which the Bay Program will include once available.


Fred Irani
U.S. Geological Survey (USGS)
(410) 267-9845

410 Severn Avenue / Suite 112
Annapolis, Maryland 21403
Tel: (800) YOUR-BAY / Fax: (410) 267-5777
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