Groundwater

The principal aquifers in the Mystic River basin are composed of sand and gravel deposited in stream channels during the last glacial period. The most productive aquifers can sustain well yields of several hundred gallons per minute and are located in the Aberjona, Malden, and Mystic River valleys. Aquifers that sustain well yields of less than 200 gal/min occur in many stream valleys and swampy areas throughout the basins. These aquifers usually cover a small surface area and are less than 50 ft thick, although their size is unknown where they adjoin or underlie fine-grained marine or lake deposits.

Bedrock is near or at the land surface in most of the basin and, in most places, can supply the few gallons per minute of water needed for domestic wells. Although bedrock wells can yield up to 110 gal/min, they generally yield 10 gal/min or less.