Quality of rivers of the United States, 1974 water year: based on the National Stream Quality Accounting Network (NASQAN)
The National Stream Quality Accounting Network (NASQAN) was established by the U.S Geological Survey to determine and compare the quality at key locations on the Nation 's major rivers. There are 345 stations in the network--data from the first 101 of these (those operating during the 1974 water year) are summarized in this report. Temperature data from NASQAN stations have been summarized for each station. At most stations the harmonic provides an estimate of daily temperatures with a standard error of estimate of 2.5 degrees C or less. According to 1974 water-year data summarized from NASQAN operations, water quality of the rivers of the United States is best (by most standards) in the Northeast, Southeast, and Northwest. Waters there generally are low in dissolved solids and major and minor chemical constitutents, generally are soft (except in Florida), and carry relatively small amounts of sediment. However, many of these waters carry moderate or high levels of major nutrients and have correspondingly high populations of attached and floating plants. High counts of indicator bacteria also show signs of local pollution at some sites. Rivers of most of the Midcontinent and Southwest are characterized by moderate to high levels of dissolved major and minor constituents, sediment, major nutrients, and biota (floating and attached aquatic plants and indicator bacteria. (Woodard-USGS)