Withdrawals from the Potomac-Raritan-Magothy aquifer system in New Jersey, which includes the Upper, Middle, and Lower Potomac-Raritan-Magothy aquifers, are the principal source of groundwater supply in northern Gloucester and northeastern Salem Counties in the New Jersey Coastal Plain. Water levels in these aquifers have declined in response to pumping. With increased population growth and development expected in Gloucester County and parts of Salem County over the next 2 decades (2005-2025), withdrawals from these aquifers also are expected to increase.