Maryland Department of Natural Resources

Charles County Observation-Well Network

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 27 wells located mainly in the central and northern part of the County. Aquifers monitored include the Patuxent (13 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 4 observation wells located in the Waldorf area (Magothy aquifer) and in the Bryans Road area (Patuxent aquifer system). 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 continue to fluctuate due to pumpage (water usage), but trends show an overall decline of about 1 foot per year (ft/yr). Water levels range from 65.78 ft below sea level at Sun Valley (CH Be 43) to 134.33 ft below sea level at St. Charles (CH Bf 133). Recent pumpage in the Waldorf area ranged from 2,085,234 gallons per day (Jan 2021) to 3,430,930 gallons per day (May 2021).

Upper Patapsco aquifer


Water levels in the Upper Patapsco aquifer system continue to show slightly declining trends with the exception of those at Douglas Point (CH Da 21), which exhibit a flat trend. Water levels range from 15.59 ft below sea level at Douglas Point (CH Da 21) to 82.03 ft below sea level at St. Charles (CH Bf 157).

Lower Patapsco aquifer


Water levels in the Lower Patapsco aquifer system observation wells have shown a flat to slightly declining trend with the exception of those at St. Charles (CH Bf 146), which show a slightly increasing trend due to a decline in nearby usage of the Lower Patapsco aquifer system. Water levels in the Lower Patapsco aquifer system range from 17.28 ft below sea level at Douglas Point (CH Da 20) to 141.57 ft below sea level at La Plata (CH Ce 56).

Patuxent aquifer


Water levels in the Patuxent aquifer system continue to decline or exhibit a flat trend due to an overall increase in pumpage. In the northeastern part of the County at Malcom (CH Bg 18), these declines have slowed in recent years. Elsewhere in the County, water levels in the Patuxent aquifer system are declining at rates of approximately 2 to 4 ft/yr with the fastest declines occurring in the Bryans Road area wells (CH Bc 75, 77, and 78). Water levels range from 13.70 ft below sea level in the western part of the county at Douglas Point (CH Da 18) to 112.19 ft below sea level at Chapman’s Landing (CH Bc 77). Recent pumpage in the Bryans Road area ranges from 408,774 gallons per day (Oct 2020) to 501,354 gallons per day (May 2021).