Stations in the USGS's National Stream Quality Accounting Network (NASQAN)

These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release. This is a point coverage of stations in the U.S. Geological Survey's National Stream Quality Accounting Network (NASQAN). NASQAN was established in 1973. Water-quality data currently is collected at NASQAN sites on bimonthly and quarterly intervals. However, some of the bimonthly stations will be sampled only five times a year beginning in 1992. Separate coverages exist for the conterminous United States, Alaska, Hawaii/Guam, and Puerto Rico. The coverages [...]