stablished in 1973 to obtain information on the quality and quantity of water draining into the oceans, describe geographic variability in water quality, detect temporal trends, and provide a nationally consistent database. Most NASQAN stations are located at the mouths of rivers and tributaries. As a result, this programís stations are broadly representative of their basins, but they cannot provide specific, detailed data to characterize the basins. This has limited the ability of the program to analyze geographic patterns in water quality. In the early 1990s, this program experienced a significant reduction in size declining from ten NASQAN stations in Minnesota in 1993 to four in 1994. Existing stations are located on the Minnesota River at Jordan, the Mississippi River at Royalton and Nininger, and the St. Louis River at Scanlon. Figure 5.1 shows the locations of the NASQAN stations, the USGS Hydrological benchmark stations and other USGS water quality monitoring stations.
Figure 5.1 Locations of NASQAN, USGS Hydrological Benchmark and other water quality monitoring stations. U.S. Geological Survey, 1993.
To assess the quality of the nationís surface and ground water, the National Water-Quality Assessment Program (NAQWA) began in 1991. The program was designed to describe the status and identify trends in water quality and identify natural and anthropogenic factors affecting water quality. The scope of the program is large, covering approximately 60 to 70% of the water used by the entire U.S. population. This information will provide water managers and policy makers with a better understanding of the geographic differences water quality and concomitant causes.
Two basins that lie partially within Minnesota are being studied as part of NAWQA: the Red River of the North Basin and the Mississippi Basin in the Minneapolis-St. Paul metropolitan area. The Red River of the North project began in 1991 and the Mississippi River project in 1994. Both projects were recently completed. USGS Water Resources Investigations Reports contain information summarizing the water quality of the basin. (See reports 3 and 4 in this series of WRC River reports for further information on these studies.)