RED RIVER OF THE NORTH BASIN, MINNESOTA, NORTH-DAKOTA, AND SOUTH-DAKOTA

The environmental setting of the Red River of the North basin within t he United States is diverse in ways that could significantly control t he areal distribution and flow of water and, therefore, the distributi on and concentration of constituents that affect water quality. Contin ental glaciers shaped a landscape of very flat lake plains near the ce nter of the basin, and gently rolling uplands, lakes, and wetlands alo ng the basin margins. The fertile, black, fine-grained soils and lands cape are conducive to agriculture. Productive cropland covers 66 perce nt of the land area. The principal crops are wheat, barley, soybeans, sunflowers, corn, and hay. Pasture, forests, open water, and wetlands comprise most of the remaining land area. About one-third of the 1990 population (511,000) lives in the cities of Fargo and Grand Forks, Nor th Dakota and Moorhead, Minnesota. The climate of the Red River of the North basin is continental and ranges from dry subhumid in the wester n part of the basin to subhumid in the eastern part. From its origin, the Red River of the North meanders northward for 394 miles to the Can adian border, a path that is nearly double the straight-line distance. The Red River of the North normally receives over 75 percent of its a nnual flow from the eastern tributaries as a result of regional patter ns of precipitation, evapotranspiration, soils, and topography Most ru noff occurs in spring and early summer as a result of rains falling on melting snow or heavy rains falling on saturated soils. Lakes, prairi e potholes, and wetlands are abundant in most physiographic areas outs ide of the Red River Valley Lake Plain. Dams, drainage ditches, and we tlands alter the residence time of water, thereby affecting the amount of sediment, biota, and dissolved constituents carried by the water. Ground water available to wells, streams, and springs primarily comes from sand and gravel aquifers near land surface or buried within 100 t o 300 feet of glacial drift that mantles the entire Red River of the N orth basin. Water moves through the system of bedrock and glacial-drif t aquifers in a regional flow system generally toward the Red River of the North and in complex local flow systems controlled by local topog raphy. Many of the bedrock and glacial-drift aquifers are hydraulicall y connected to streams in the region. The total water use in 1990, abo ut 196 million gallons per day, was mostly for public supply and irrig ation. Slightly more than one half of the water used comes from ground -water sources compared to surface-water sources. Most municipalities obtain their water from ground-water sources. However, the largest cit ies (Fargo, Grand Forks and Moorhead) obtain most of their water from the Red River of the North. The types and relative amounts of various habitats change among the five primary ecological regions within the R ed River of the North basin. Headwater tributaries are more diverse an d tend to be similar to middle-reach tributaries in character rather t han the lower reaches of these tributaries for the Red River of the No rth. Concentrations of dissolved chemical constituents in surface wate rs are normally low during spring runoff and after thunderstorms. The Bed River of the North generally has a dissolved-solids concentration less than 600 milligrams per liter with mean values ranging from 347 m illigrams per liter near the headwaters to 406 milligrams per liter at the Canadian border near Emerson, Manitoba. Calcium and magnesium are the principal cations and bicarbonate is the principal anion along mo st of the reach of the Red River of the North, Dissolved-solids concen trations generally are lower in the eastern tributaries than in the tr ibutaries draining the western