|Hydrogeology & Hydrology Program|
|Anne Arundel County Project||
contact: David Andreasen (email@example.com)
[Final Report in PDF format (1,449 kb)]
Water for domestic supply in southern Anne Arundel County is pumped almost entirely from individual wells screened in the Aquia aquifer. Large, individual supplies (public or commercial) account for a relatively small part of the total water pumped. The Aquia aquifer is the most desirable source of ground water in the area, given its relatively shallow depth and generally acceptable water quality. The Aquia aquifer is both confined (artesian aquifer) and unconfined (water-table aquifer) in southern Anne Arundel County. The deeper Magothy aquifer--capable of supplying large quantities of water to wells--is an additional, easily obtained source of ground water in southern Anne Arundel County. However, the presence of elevated iron concentrations may make it less appealing for individual, residential use. Currently, the Magothy aquifer is used primarily for irrigation and minor public supply. Approximately 0.3 million gallons per day (Mgal/d) was pumped from the Magothy aquifer in southern Anne Arundel County in 1998. In comparison, the Aquia aquifer was pumped at a rate of approximately 2 Mgal/d in 1998. Increased demand on the Aquia aquifer in southern Anne Arundel County and in areas south have caused water levels to decline. The current rate of water-level decline is approximately 1-2 feet per year in the confined part of the aquifer. The declining water levels have resulted in moderate reductions in the available drawdown. Increased production of the Aquia aquifer caused by the growing population will result in additional drawdown. Effective water-supply management to insure long-term productivity of the Aquia aquifer requires an evaluation of the impact of both current and estimated future pumpage on water levels. Previous water-supply studies of the Aquia aquifer (Chapelle and Drummond, 1983; Achmad and Hansen, 1997) included southern Anne Arundel County, but were focused primarily on Calvert and St. Mary's Counties where withdrawals are greatest. The purpose of this study is to (1) determine the hydraulic characteristics of the Aquia and Magothy aquifers and quantify their water-supply potential in southern Anne Arundel County, and (2) determine the cumulative impact of increasing ground-water pumpage in Anne Arundel, Calvert, and St. Mary's Counties on future Aquia water levels in southern Anne Arundel County.
An additional purpose of the study is to quantify the natural water quality of the Aquia and Magothy aquifers and determine any spatial trends in water quality. Water quality of the Aquia aquifer is generally good; however, at some locations, elevated iron, hydrogen sulfide, and calcium concentrations result in poor water quality. These constituents do not pose health risks but are aesthetically undesirable--collectively causing iron stains on clothing and plumbing fixtures, "rotton-egg" smell, reduced ability to form soap lather, and formation of white scale on the heating of water. Residential water-treatment systems are widely used to correct these water-quality problems at varying levels of effectiveness and cost. The Aquia aquifer may also be locally susceptible to brackish-water intrusion on the northern end of the Shady Side peninsula where the aquifer is overlain by less confining material. Water from the Magothy aquifer in central Anne Arundel County and from the few wells tested in southern Anne Arundel County have elevated iron concentrations. There is, however, an insufficient number of water analyses from the Magothy aquifer in southern Anne Arundel County to characterize its water quality adequately.
Achmad, G., and Hansen, H. J., 1997, Hydrogeology, model simulation, and water-supply potential of the Aquia and Piney Point-Nanjemoy aquifers in Calvert and St. Mary's Counties, Maryland: Maryland Geological Survey Report of Investigations No.64, 197 p.
Chapelle, F. H., and Drummond, D. D., 1983, Hydrogeology, digital simulation, and geochemistry of the Aquia and Piney Point-Nanjemoy aquifer system in southern Maryland: Maryland Geological Survey Report of Investigations No. 38, 100 p.