The U.S. Environmental Protection Agency (USEPA) is working to develop watershed diagnostic tools to assess the causes and pollutant sources of impairment in aquatic systems in New England. A previous USGS New England study (Coles and others, 2004 ) showed that urbanization in the region could be effectively characterized by an index of urban intensity, and that several biological, physical, and chemical factors of the aquatic ecosystem were strongly and consistently affected by urbanization. USEPA, in cooperation with the USGS, is working to refine a method for establishing ecological reference conditions and apply the methodology to specific regulatory needs within New England.
USGS contributions to this effort will include providing the watershed attributes for sampling stations throughout New England necessary to define and refine a watershed development index, using the USGS urban intensity index (UII) as a starting template. Basin characteristics such as land cover classification, mean annual flow and velocity, mean annual temperature and precipitation, slope of the stream segment, proportions of impervious surface and forest canopy, road density, number of point source discharges, number of dams, number of toxic release sites, and Census demographic data will be calculated for the watersheds of 438 ecological sampling sites. Values will be generated for the local catchment and the cumulative total of upstream catchments for each site. Each monitoring station has been assigned to a catchment in the National Hydrography Dataset Plus (NHDPlus), in order to take advantage of this extensive network of hydrologic features and attributes. This work will be completed in 2008.