This illustration demonstrates the aquifers that provide potable water to southern Maryland.
BALTIMORE (September 21, 2007) A new report from the Maryland Department of Natural Resources (DNR) Maryland Geological Survey (MGS) presents the results of a five-year study of groundwater supply potential from confined aquifers in southern Maryland. MGS geologists presented the report, Water-Supply Potential of the Coastal Plain Aquifers in Calvert, Charles, and St. Marys Counties, Maryland, With Emphasis On The Upper Patapsco and Lower Patapsco Aquifers, to the Tri-County Council this week.
Currently water needs of southern Maryland are predominantly supplied by five major aquifers - Piney Point, Aquia, Magothy, Upper Patapsco, and Lower Patapsco. Declining water levels are a concern in the Aquia, Magothy, and Upper and Lower Patapsco aquifers. Elevated arsenic levels in parts of the Aquia Aquifer have prompted water-supply managers to consider shifting a portion of ground-water withdrawals from the Aquia aquifer to the deeper Upper Patapsco and Lower Patapsco aquifers.
A groundwater flow model was used to estimate future water levels in each major aquifer through 2030, based on future pumpage scenarios compiled in conjunction with county planning departments. Simulations indicate that Calvert and St. Marys Counties could meet projected water needs by increasing usage of the Aquia Aquifer, or by shifting up to 50 percent of public supply withdrawals from the Aquia Aquifer to the Upper Patapsco Aquifer.
Given the future scenarios simulated in this study, areas in central and western Charles County would not be able to supply future water needs in 2030 without causing drawdowns exceeding Maryland Department of Environment management levels. Simulated future drawdowns also indicate potential problems in the shallow portions of the Upper Patapsco and Lower Patapsco aquifers, such as river-water intrusion, and possibly reduced base flow to streams and altered ecology of wetlands. Alternative water-supply options that could reduce these water-level declines in Charles County include utilizing the Patuxent aquifer, or replacing current production well fields with new wells in the Patapsco aquifers farther southeast.
The study, which was a cooperative effort between the Maryland Geological Survey, the U.S. Geological Survey, and Charles, Calvert, and St. Marys Counties, was undertaken to address these concerns. Funding for the five-year project was provided by Calvert, Charles, and St. Marys Counties, the U.S. Geological Survey, Maryland Geological Survey, and the Chesapeake Ranch Water Company.
The complete presentation is available at