In general, yield of water from individual wells in unconsolidated surficial deposits is low (0-10 gallons per minute). Several small, unconsolidated deposits may yield moderate quantities (50-100 gallons per minute) but these have not been adequately tested.
Yields from 160 wells in the crystalline bedrock range from 0.5 gallons per minute to 100 gallons per minute, with a median yield of 10 gallons per minute. Wells in zones of extensive fracturing or faulting generally have higher than average yields. Zones of fracturing may correspond to lineations which have been mapped by interpretation from topographic maps and aerial photographs.
In general, ground water is of suitable chemical quality for public supply. Most ground water is low in dissolved solids and is soft. Iron exceeds 0.3 milligrams per liter and manganese exceeds 0.05 milligrams per liter in water from some wells. Brackish (salty) water is present in only a few wells at the coast or adjacent to saltwater bodies. Elevated concentrations of Radon-222 have been reported from wells in the granite aquifer.