The estimated population in the largely rural study unit is 418,000 people. Minn. About 12,000 Native Americans live on the Fort Totten, Red Lake, Sisseton, Turtle Mountain, and White Earth Indian Reservations, which are either wholly or partly within the study unit. Principal crops include wheat, barley, oats, sugar beets, potatoes, corn, beans, hays, and sunflowers. The Red River of the North receives most of its flow from its eastern tributaries largely as result of regional patterns in precipitation, evapotranspiration, soils, and topography. Annual runoff varies greatly, but most runoff occurs in spring and early summer from rains falling on saturated soils.
Flooding is a major problem aggravated by the flat slope of the Red River of the North.
Channel obstructions such as ice jams, felled trees, and man-made structures can cause backwater that increases flood elevations locally. Natural lakes, ranging in surface area from 10 to 13,800 acres, occur at a density of greater than 10 lakes per 10 square miles in the southeastern part of the study unit. The study unit also contains thousands of natural wetlands. Ground water that is discharged to streams and springs or is pumped from wells primarily comes from sand and gravel aquifers near land surface or buried within the glacial drift that mantles the entire study unit. Eutrophication-Nitrate and phosphate in surface runoff from cropland fertilizers and industrial and municipal sewage effluent accelerates enrichment of nutrients in lakes, reservoirs, and streams.