Ground-water resources of the Mattapoisett River aquifer, Plymouth County, Massachusetts: Summary for water-resource managers

Proposed increases in municipal pumpage in the Mattapoisett River valley will triple ground-water withdrawals in the next two decades. Because of State and local concern about the long-term effects of these withdrawals on ground-water levels and streamflow, a digital ground-water-flow model was developed to assist water-resource management. Ten development scenarios representing existing and proposed withdrawals were simulated using drought conditions. Under conditions simulating 1965, the driest year of record, predicted water levels in the aquifer are as much as 9 feet lower than average. Under severely dry conditions, simulating only enough recharge to keep the river flowing with no pumping, the predicted water levels are as much as 19 feet lower than average. During the greatest pumping demands, the predicted drawdown in five wells could cause well failure. Simulated pumping demands in six scenarios use all available ground-water discharge. Under severely dry conditions, it is predicted that the downstream half of the river will stop flowing under most pumping plans. (USGS)