Maryland Department of Natural Resources

Charles County Observation-Well Network

Project Details

The Charles County water-level network is one of three county observation-well networks maintained by MGS and funded through county cooperative agreements. Other counties include Anne Arundel and Queen Anne’s counties.

The primary objective of these networks is to monitor the effects of water-supply withdrawals on groundwater levels at both a local (well field) and regional scale. More specifically the water-level data are used to help assess (1) long-term sustainability of the water supply; (2) well interference (drawdown at each well in a multiple-well system added to drawdowns at the other wells); (3) potential for increased development of the aquifers; (4) potential for salt-water intrusion, where applicable; and (5) the role of ground-water extraction in land subsidence.

The Charles County observation-well network, initiated in 1999, is currently funded through a cooperative agreement between Maryland Geological Survey and Charles County Department of Planning and Growth Management. The network currently consists of 28 wells located mainly in the central and northern part of the County. Aquifers monitored include the Patuxent (14 wells), Lower Patapsco (8 wells), Upper Patapsco (4 wells), and Magothy (2 wells). Frequency of measurement ranges from 6 times a year to semiannual (spring and fall). Groundwater withdrawals are also correlated with continuous water levels in 8 observation wells located in the Waldorf area (Magothy, Upper Patapsco, Lower Patapsco, and Patuxent aquifers) and in the Indian Head/Bryans Road area (Lower Patapsco and Patuxent aquifer systems). Pumpage data were obtained from Charles County Department of Public Utilities. Generally, for all aquifers, increased pumpage occurs during summer and fall, causing water levels to decline while decreased pumpage occurs during winter and spring, causing a deceleration of declines.



Current Water Level Trends

Magothy aquifer


Water levels in the Magothy aquifer fluctuate with usage and continue to decline gradually. The largest fluctuations, up to 50 feet, occurred at St. Charles (CH Bf 133). Water levels in the Magothy aquifer range from 69.64 ft below sea level at Sun Valley (CH Be 43) to 134.67 ft below sea level at St. Charles (CH Bf 133). Pumpage in the Waldorf area ranged from 2.41 million gallons per day (July 2025) to 3.91 million gallons per day (August 2025).

Upper Patapsco aquifer


Water levels in the Upper Patapsco aquifer system fluctuate seasonally up to five feet but show a declining trend with the exception of Smallwood West (CH Be 60) and St. Charles (CH Bf 157), where water levels have been recovering and flat, respectively, since 2020. Water levels in the Upper Patapsco aquifer system range from 17.14 ft below sea level at Douglas Point (CH Da 21) to 81.97 ft below sea level at St. Charles (CH Bf 157).

Lower Patapsco aquifer


Water levels in the Lower Patapsco aquifer system fluctuate seasonally and have exhibited flat or recovering trends in the Bryans Road area, and decline to the south in La Plata (CH Ce 56), Douglas Point (CH Da 20) and Chapel Point Woods (CH De 52). Fluctuations due to pumping are especially apparent in the La Plata area (CH Ce 56) where water levels varied as much as 25 feet. Water levels in the Lower Patapsco aquifer system range from 18.72 ft below sea level at Douglas Point (CH Da 20) to 164.09 ft below sea level at La Plata (CH Ce 56). Recent pumpage in the Waldorf area ranged from 1.42 million gallons per day (Sept 2025) to 2.72 million gallons per day (July 2025).

Patuxent aquifer


Water levels throughout the Patuxent aquifer system have declined steadily over the past year. In the eastern part of the county, the Malcom well (CH Bg 18) has shown an accelerated decline since 2021. This decline is likely driven by continued Patuxent usage at the Chalk Point Power Plant, despite shutting down its coal-fired units. In western Charles County, water levels at Chapmans Landing, Bryans Road and Mattawoman Waste Water Treatment Plant (CH Bc 75, CH Bc 77, CH Bc 78 and CH Cc 34), are declining at rates of approximately 5 ft/yr. Water levels in the Patuxent aquifer system range from 15.53 ft below sea level in the western part of the county at Douglas Point (CH Da 18) to 130.74 ft below sea level at Chapman’s Landing (CH Bc 75). Recent pumpage in the Bryans Road area ranged from 481,355 gallons per day (Jan 2026) to 558,764 gallons per day (June 2026).