Groundwater

The most productive aquifers in the French and Quinebaug River basins are composed of glacial sand and gravel outwash and occur in thin, narrow, discontinuous deposits beneath valleys and lowlands in about 16 percent of the basins. Major aquifers, such as in the Quinebaug River valley, yield at least 300 gal/min to municipal wells and smaller aquifers, such as in the tributary streams of Cady, Hammett, Hachet, and Hollow Brooks, yield less than 100 gal/min to wells.

Bedrock in the French and Quinebaug River basins is used as a source of water for domestic wells. Bedrock wells in the basin yield from less than a gallon per minute to 210 gal/min, and average about 10 gal/min. Wells with the highest yields, more than 100 gal/min, are in the town of Leicester in the northern part of the French River basin. This area has some of the very few municipal wells completed in bedrock in Massachusetts.