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5,000 CHRISTOPHER M. KAVANAUGH 9 ,-""', I " I I I I I / / / / / 4,000 "ii) E 3,000 & li &. cJ <II is 2,000 1,000 - ".. ,/ ---_/ -- Fig. 2. Instantaneous discharge (cfs) in the Minnesota River in August 1989 and August 1990. - o 463 436 383 352 327 283 243 216 193 172 146 62 River Kilometer 1989 1990 Physical and Chemical Monitoring The objectives of physical and chemical moni- toring are to (1) identify sources and loadings of nutrients, suspended sediment, biochemical oxy- gen demand, and organic carbon in the river; (2) calculate the movement of sediment and associ- ated pollutants between points on the river; and (3) identify areas of bank erosion and associated deposition of sediment to determine the magni- tude and impact ofloadings of sediment within the river channel versus from upland areas. Physical and chemical characteristics were monitored at 11 mainstem sites, 10 tributary sites, and 3 reservoir sites (Table 2). Monitoring began in 1989 and continued through 1992. Loadings and concentrations of nutrients and sediments were much higher than expected consid- ering the size and gradient of the mainstem. Con- centrations of nutrients, specifically nitrates, in- creased in a downstream progression. Concentration of cWorophyll a, attributable mainly to algae, in the river exceeded normal levels and also increased in a downstream progression. Coli- form bacteria, of human and animal origin, also exceeded normal levels. Although preliminary at this point, the hypothe- sis is that dramatic alteration of drainage within the basin from ditching and tiling activities prob- ably increased concentrations and total loading of nutrients in the river. The Blue Earth River (rkm 180) seems to be the most significant contributor of nutrients to the Minnesota River and is currently being studied intensively to identify sources of nu- trient loading. Land Use Subcommittee More than 75% of the land use within the Min. nesota River basin is agricultural (row crops--com, soybeans, sugar beets). The number of anirnRI feed. lots is decreasing; however, the size of individual feedlots, particularly hogs and poultry, is increas- ing within the basin. Open ditch and tile drainage systems are found on more than one-third of the cultivated land, contributing soil and nutrients to the river (King 1985). The Minnesota River basin can be separated into 1,208 minor watersheds that make up the surface water flow to the river system. Of these, 1,113 are in Minnesota, 18 in Iowa, and 77 in South Dakota. Any activity within a watershed has the poten- tial to affect water quality and biotic integrity within the watershed, and what happens in minor watersheds may ultimately have an effect in the mainstem. The land use subcommittee is studying existing land use characteristics within the basin on the four levels described below.