Evaluation of yields of wells in consolidated rocks, Virginia to Maine

In the North Atlantic region, Virginia to Maine, yields of industrial and municipal wells are the most reliable indicators of the water-yielding potential of consolidated rocks. Generally, such wells represent efforts to develop a maximum supply of water, they are 350 to 500 feet deep, and they utilize 60 to 150 feet of drawdown. In multiple-well developments, average yields of wells per 100 feet of drawdown range from less than 75 gallons per minute in the least favorable rocks such as shale or granite gneiss to as much as 300 gallons per minute in limestone. In any one rock type, substantially greater than average sustained yields are possible in structurally deformed areas or in areas where recharge potential is especially favorable.