Characterization of selected biological, chemical, and physical conditions at fixed sites in the Upper Colorado River basin, Colorado, 1995-98

Biological community samples were collected at 15 sites in the Upper Colorado River Basin (UCOL) in Colorado as part of the National Water-Quality Assessment (NAWQA) Program. Sites sampled in two physiographic provinces, the Southern Rocky Mountains and the Colorado Plateau, represented agriculture, mining, urban and recreation, and mixed land uses and background conditions. Nine measures of water quality, which include information on nutrients, specific conductance (a surrogate for salinity), trace elements in streambed sediment, pesticides in fish tissue, fish communities, and macroinvertebrate richness and composition and stream habitat were used for comparisons among sites within the two physiographic provinces. Sampling sites from three other NAWQA study units-the Rio Grande Valley, the South Platte River Basin, and the Upper Snake River Basin study units-were categorized on the basis of land use and stream size in order to develop a larger data set for comparison to sites in the