The surface waters component of the Environmental Monitoring and Assessment Program (EMAP): an overview

The U.S. EPA is developing a new monitoring program, the Environmental Monitoring and Assessment Program (EMAP), to monitor and assess the ecological health of major ecosystems, including surface waters, forests, near-coastal waters, wetlands, agricultural lands, arid lands, and the Great Lakes, in an integrated, systematic manner. The program is designed to operate at regional and national scales, for decades, and to evaluate the extent and condition of entire ecological resources. EMAP has a common sampling framework for all resource types. The frame consists of a systematic grid of about 12,500 points in the conterminous United States that can be subdivided into subgrids of varying densities. A subset of 3,200 40 km² hexagons will be selected for field sampling of surface water resources. A four-year resampling cycle will allow approximately 800 lakes and 800 stream sites to be evaluated annually. Ecological assessments for surface waters will address three environmental values of concern: biotic integrity, fishability, and trophic state. The focus will be on biological assemblages, including fish, zooplankton, macroinvertebrates, birds and diatoms, as response indicators of ecological condition.