Ground water favorability and surficial geology of the Portland area, Maine

This hydrologic atlas describes the surficial geology and groundwater resources of about 240 square miles in Cumberland County, Maine. The most productive aquifers are outwash and ice-contact deposits. Their locations and the most favorable areas for obtaining large yields from them are indicated on the map. The largest reported yield from a well in unconsolidated deposits is 100 gpm, but it is likely that in places as much as 500 gpm can be obtained from properly located and developed wells. Ground water is available to drilled wells in bedrock in sufficient quantity for domestic use. The average yield from bedrock wells is 11 gpm, the median yield is 5 gpm, and the maximum reported yield is 150 gpm. The quality of the water is generally good, although brackish or salty water is obtained by some wells on the coast. (Woodard-USGS)