Groundwater is the water beneath the land surface that fills the spaces in rock and sediment. It is replenished by precipitation.
Under natural conditions much of that recharge returns to the atmosphere by evaportranspiration from plants and trees or dicharges to surface waters. Groundwater discharge to surface waters allows streams to flow beyond rain and snowmelt periods and sustains lake levels during dry spells.
Groundwater supplies about 75 percent of Minnesota's drinking water and nearly 90 percent of water used for agricultural irrigation. Availability varies throughout the state and may be limited in some ares for larger withdrawals.