Simulation of Effects of Ground-Water Development on Water Levels in Glacial-Drift Aquifers in The Brooten-Belgrade Area, West-Central Minnesota

Ground-water flow in the confined- and unconfined-drift aquifers in the Brooten-Belgrade area of west-central Minnesota was simulated with a threedimensional finite-difference ground-water-flow model. Model results indicate that about 96 percent of the total inflow to the modeled area is from precipitation. Discounting evapotranspiration, 63 percent of the total outflow is ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers, and 34 percent is ground-water pumpage. The model was used to simulate the steady-state effects of below-normal precipitation (drought) and hypothetical increases in ground-water development. Model results indicate that reduced recharge and increased pumping during a hypothetical 3-year extended drought would lower regional water levels from 2 to 5 feet in each aquifer and as much as 20 feet in the lowermost aquifer zone; ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers would be reduced by 38 percent. The addition of 10 to 20 hypothetical wells in confined aquifers, pumping 123 to 246 million gallons per year, would result in regional water-level declines of 0.1 to 0.5 feet. Simulated water-level declines in wells completed in the lower part of the system would be as much as 5.0 feet as a result of pumping 246 million gallons per year from 20 hypothetical wells. Water-level declines in overlying and underlying aquifers would range from 0.4 to 2.8 feet. Ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers would be unaffected by the pumpage.