The 2011 National Wetland Condition Assessment

Background/Question/Methods

The ecological condition of wetland resources across the conterminous United States is poorly understood.  To address this issue, the U.S. Environmental Protection Agency (USEPA), in collaboration with states, tribes, and other federal partners, is conducting the first-ever National Wetland Condition Assessment (NWCA).  The NWCA is the fifth in a series of National Aquatic Resources Surveys (NARS) completed by USEPA to improve understanding of the quality of the Nation’s aquatic resources.  The analysis approach of the NWCA, and other NARS studies (e.g., National Lakes Assessment,  National Rivers and Streams Assessment), is to identify and develop indicators of ecological condition, which are evaluated in relation to measures of stress, disturbance, and reference condition.   Understanding these relationships facilitates identification of potential causes of decline in, or threats to, ecological condition.  The 2011 NWCA will provide baseline description of wetland quality across the Nation, with subsequent iterations at 5-year intervals, dependent on funding.  Results of the NWCA will be valuable in informing decision-making regarding use, management, and protection of wetland resources.

Results/Conclusions

Field work for the first NWCA was conducted in spring and summer of 2011.  Data describing vegetation, algae, soil characteristics, soil chemistry, water chemistry, hydrology, and stressors were collected from 1,179 wetland assessment areas (0.5 ha) across the contiguous United States, representing eight US Fish and Wildlife Status and Trends wetland classes.  The assessment areas represented 898 probability-selected sites based on the NWCA survey design, 131 intensification sites added to increase sample size within particular states, and 150 hand-picked candidate reference sites.  Preliminary water chemistry results indicate that among sites with water at the date of sampling, 68% were freshwater systems and 32% were brackish/saltwater systems.  Across all sites, 63% occurred on private, 20% on federal and 17% on state and tribal land.  Here we present 1) field methodology for data collection, emphasizing vegetation, 2) status of data entry and validation for vegetation, including reconciliation of species names to a standard nomenclature, and 3) preliminary results on the extent of wetland resources by wetland class.

A report describing results from the 2011 NWCA is scheduled for completion in 2013, and will describe status of wetland condition across the Nation (e.g., based on a variety of metrics or multimetric indices such as a Vegetation Index of Biotic Integrity or an Index of Wetland Condition), the extent of wetland area impacted by stressors, and relationships between stressors and ecological condition.