Maryland Department of Natural Resources


Effects of increased withdrawals from the Aquia aquifer on the Mayo Peninsula, Anne Arundel County, Maryland with an evaluation of water quality

2018, Gemperline, J.M., VanDerwerker, T.J., and Andreasen, D.C.

Report of Investigations 84

Key Results

The Mayo Peninsula in east-central Anne Arundel County, Maryland relies primarily on the Aquia aquifer for drinking-water supply. The deeper Magothy aquifer is also utilized but to a much lesser extent. The lifting of a building moratorium in 2017 on the peninsula associated with increased capacity for treating sewage effluent may result in the construction of up to approximately 630 homes (an approximate 20 percent increase over the number of housing units in 2010). The potential effects of increased domestic water withdrawals to support the possible growth on water levels and on the brackish-water interface in the Aquia aquifer were evaluated. In addition, water quality of the Aquia aquifer, both natural and affected by anthropogenic contaminants, that might constrain the use of the aquifer for domestic potable supply was also evaluated.


The potential increase of between 0.093 and 0.158 million gallons per day resulting from the possible new development on the Mayo Peninsula was evaluated using a one-layer numerical groundwater-flow model (MODFLOW) to estimate the effects on water levels in the Aquia aquifer and on the brackish-water/freshwater interface. The two rates are based on estimated household water-use rates of 147 and 250 gallons per day, respectively.


Water quality of the Aquia aquifer on the Mayo Peninsula is generally good; however, in areas near the shoreline (less than 600 feet), chloride concentrations are commonly elevated resulting from brackish-water intrusion. Additionally, anthropogenic contamination from the surface may affect the potability of water from the Aquia. A total of 24 wells were sampled during this study to characterize the water quality of the Aquia aquifer; one well screened in the Magothy aquifer was also sampled for comparison.

Downloads and Data

Report of Investigations 84 (pdf, 12.6 MB)