Supplemental irrigation of well-drained sandy soils has prompted an evaluation of ground water in the Appleton area. Glacial drift aquifers are the largest source of ground water. The surficial outwash sand and gravel is the most readily available and the most areally extensive drift aquifer, and it underlies much of the sandy soil area. Saturated thickness of the outwash is more than 80 feet (24 m) in places, and potential well yields may exceed 1,200 gal/min (76 1/s) in some areas. In about 17 percent of the area, yields of more than 300 gal/min (19 1/s) are obtainable.
Recharge to the outwash aquifer occurs primarily during the spring thaw and averages about 5 inches (12.7 cm) annually. Most discharge from the aquifer appears as base flow in the Pomme de Terre River. Despite dissolved-solids concentrations ranging from 280 to 1,350 mg/1, the water is chemically suitable for irrigation.
Mathematical models of a part of the aquifer were made to evaluate the effects of 20 successive years of ground-water withdrawal for three irrigation-development patterns. It was estimated that the present annual withdrawal rate of 1,410 acre-ft (1.74 hm3) would result in water-level declines of less than 3 feet (0.9 m). However, annual withdrawals of 8,450 acre-ft (10.4 hm3) would cause aquifer dewatering and decreased well yields in some places. After a new state of equilibrium was established in response to withdrawals, most of the withdrawal would be supplied by diverted base flow from the Pomme de Terre River.
