Wetland acreage in the US declined during 2004-2009, reversing a slightly positive trend of net wetland gains during 1998-2004, according to the latest assessment from the US Fish and Wildlife Service, released Oct. 6, 2011. Prior to 1998, huge wetland losses were occurring, though the magnitude had generally been diminishing since the 1950s.
- "Status and Trends of Wetlands in the Conterminous United States, 2004 to 2009"  (dated September 2011).
The worst recent net wetland losses were in freshwater forested areas or estuarine intertidal areas, and the geographic areas most affected were the Southeast, the Great Lakes region, the Prairie Pothole region, and many metropolitan areas. Among the causes of ongoing losses were sea-level rise, coastal storms, climate change, development, and resource extraction. Reconstruction, expansion, and improvements to wetlands have offset acreage losses to a certain extent, but the report didn't assess the quality or functional capabilities of these constructed settings.
There is considerable detail in the report, as well as a map of the nation's 37 physiographic regions, allowing you to cover this topic at the national, regional, and local scales.
The list of agencies and individuals in Appendix A provides numerous possible sources of expertise. Other sources are available through:
- Association of State Wetland Managers  (includes links to many other organizations  that have some type of interest in or responsibility for wetlands).
This report is a product of a bigger effort: