Maryland Department of Natural Resources

Anne Arundel County Observation-Well Network

Project Details

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

Location of network observation wells

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 Anne Arundel County observation-well network, initiated in 1986, is currently funded through a cooperative agreement between Maryland Geological Survey and Anne Arundel County Department of Public Works. The network consists of 42 wells located mainly in the central and northern part of the County. Aquifers monitored include the Patuxent (7 wells), Lower Patapsco (19 wells), Upper Patapsco (9 wells), Magothy (6 wells), and Aquia (1 well). Frequency of measurement is 6 times a year, semiannual (spring and fall), or continuous.



Current Water-Level Trends


Aquia aquifer


Water levels were measured in one well in this aquifer. The water level in Southern Anne Arundel County at the Deale Athletic Field (AA Fe 92) was 32.75 ft below sea level in August 2023. Over recent years, the water level has fluctuated less than a foot. The overall water-level trend in this well has remained flat. The flattening of the trend is largely a result of the reduction of withdrawals from the Aquia aquifer in St. Mary’s County as pumpage was shifted to the deeper Upper Patapsco aquifer to avoid elevated arsenic concentrations in the Aquia aquifer.

Magothy aquifer


Water levels were measured in 6 wells in this aquifer. Current levels range from 2.17 ft above sea level west of Annapolis (AA Dd 42) to 25.76 ft below sea level in Broad Neck (AA Cf 99). Overall water-level trends in the Magothy aquifer, since 2015, continued to be flat.

Upper Patapsco aquifer


Water levels were measured in 9 wells in this aquifer. Current levels range from 73.28 ft above sea level in northern Anne Arundel County (AA Ad 108) to 26.67 ft below sea level at the Broad Creek Water Treatment Plant (AA De 95). Recent pumpage in Broad Creek ranged from 0 gallons per day (Oct and Nov 2023) to 1.29 million gallon per day (April 2024). Overall, water-levels in the Upper Patapsco aquifer exhibit a flat to slightly increasing trend within the past decade. Water levels in the Upper Patapsco aquifer fluctuated as much as 5 feet at Central Ave (AA De 128) and Sandy State Park (AA Cg 24), while at Broad Creek (AA De 95) they fluctuated as much as 14 feet in response to water use.

Lower Patapsco aquifer


Water levels were measured in 19 wells in this aquifer. Current levels range from 74.69 ft above sea level in northern Anne Arundel County (AA Bd 160) to 89.58 ft below sea level in the Arnold well field (AA Cf 167). Recent pumpage in Crofton ranged from 4.6 million gallons per day (Dec 2023) to 9.13 million gallons per day (July 2023) (tab. 2). In Arnold, recent pumpage ranged from 1.57 million gallons per day (Nov 2023) to 6.33 million gallons per day (June 2024). Overall water levels in this aquifer fluctuated in response to water use, especially in Crofton (AA Cc 115) where water levels fluctuated as much as 46 feet, and Arnold (AA Cf 167) where levels varied almost 26 feet. Despite fluctuations in response to pumpage, overall trends were flat or increasing in all wells except at Kings Heights Water Treatment (AA Cc 82) and the Glen Burnie area (AA Ad 109, AA Bc 215, AA Bd 152, Bd 156 – 158, 160), where water levels have declined in recent years.

Patuxent aquifer


Water levels were measured in 7 wells in this aquifer. Current levels range from 20.97 ft above sea level south of Ft. Meade (AA Cb 1) to 128.05 ft below sea level at the Arnold well field (AA Cf 166). Recent pumpage in Crofton ranged from 4.20 million gallons per day (April 2023) to 7.03 million gallons per day (June 2024). Recent pumpage in Arnold ranged from 1.48 million gallons per day (Feb 2024) to 4.04 million gallons per day (June 2024). Water levels in this aquifer fluctuated in response to water use especially in Glen Burnie (AA Ad 90) and Arnold (AA Cf 166) where water-level varied as much as 33 feet and at Crofton (AA Cc 135) which varied as much as 23 feet. Over the past decade, almost all wells declined in response to increased withdrawals, except at Glen Burnie (AA Ad 90) and Sandy Point (AA Cg 22) where levels have flattened.