Preimpoundment Water Quality of The Wild Rice River, Norman County, Minnesota

Water samples have been collected at two sites on the Wild Rice River since September 1974 to establish baseline water-quality characteristics before construction of a reservoir near Twin Valley, Minnesota for recreation and flood control. A decline in water quality between the sites is shown by mean total phosphorus concentrations, which Increase from 0.06 to 0.10 milligrams per liter downstream, and mean turbidity, which increases from 12 to 24 units downstream. Phosphorus and ammonia concentrations as high as 0.31 and 2.7 milligrams per liter, respectively, could be the result of domestic waste input to the river upstream from Hendrum. Biochemical oxygen demand concentrations were significantly higher during spring runoff than during the rest of the year. Four out of 90 bacteria samples taken at Twin Valley indicate the presence of human fecal material, though bacteria densities do not exceed recommendations of the U.S. Environmental Protection Agency for public-water supplies. The dominance of organic-pollution tolerant phytoplankton in 49 out of 78 samples might indicate degradation of the river quality at Twin Valley. Nutrient concentrations at Twin Valley have no apparent effect on phytoplankton concentrations. None of the constituents sampled were found to exceed concentrations recommended by the Environmental Protection Agency for public-water supplies.