Maryland Department of Natural Resources

Charles County Observation-Well Network

The Charles County water-level network is one of five observation-well networks maintained by MGS and funded through cooperative agreements with Anne Arundel, Calvert, Charles, Queen Anne’s, and St. Mary’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 29 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 (5 wells), and Magothy (3 wells). Frequency of measurement ranges from 6 times a year to semiannual (spring and fall).



Current Water Level Trends


hydrograph for observation well CH Bf 133 in the Magothy aquifer

Magothy aquifer


Water levels in the Magothy aquifer continue to fluctuate in response to pumpage, but generally show slightly declining or flat trend. Current water levels range from 69.11 feet below sea level at Sun Valley (CH Be 43) to as much as 116.97 feet below sea level at St. Charles (CH Bf 133).

hydrograph for observation well CH Bf 157 in the Upper Patapsco aquifer

Upper Patapsco aquifer


Water levels in the Upper Patapsco aquifer have continued to decline in the last year at John Hanson Middle School (CH Bf 158) and Smallwood West (CH Be 60). Water levels appear to have stabilized at St. Charles (CH Bf 151 and 157) and Douglas Point (CH Da 21). Current water levels range from 14.94 feet below sea level at Douglas Point (CH Da 21) to as much as 71.39 feet below sea level at St. Charles (CH Bf 151).

hydrograph for observation well CH Bc 24 in the Lower Patapsco aquifer

Lower Patapsco aquifer


Water levels in the Lower Patapsco aquifer in wells in the far northern and northwestern parts of the county (CH Be 72, CH Bc 24, CH Bc 81, and CH Cc 31) have either recovered or held steady since 2012, for which downward trends were noted. Lower Patapsco water levels at St. Charles (CH Bf 146), La Plata (CH Ce 56), Chapel Point Woods (CH De 52), and Douglas Point (CH Da 20) continue to show a flat to slightly declining trend. Current water levels in the Lower Patapsco aquifer range from 16.58 feet below sea level at Douglas Point (CH Da 20) to 144.99 feet below sea level at St. Charles (CH Bf 146).

hydrograph for observation well CH Bc 75 in the Patuxent aquifer

Patuxent aquifer


For all monitored areas of the county, water levels in the Patuxent aquifer continue to decline. Water levels in the Patuxent aquifer are declining at rates of 2.5 to 5 ft per year at Waldorf, La Plata, and Indian Head area wells, while Chapmans Landing/Bryans Road area wells (CH Bc 75, 77, and 78) record the fastest declines at up to 7 ft per year. Current water levels in the Patuxent aquifer range from 11.20 feet below sea level in the western part of the county at Douglas Point (CH Da 18) to 85.11 feet below sea level at Chapman’s Landing (CH Bc 77).