USGS - science for a changing world

Water Science for Maryland, Delaware and the District of Columbia

Groundwater Levels

The USGS monitors groundwater levels in surficial or unconfined aquifers, providing observations that can be compared to both short-term and long-term changes in weather conditions. The groundwater wells used for the monthly water summary were selected based on the following criteria:

  • Located in a surficial or unconfined (water-table) aquifers
  • Open to a single, known hydrogeologic unit/aquifer
  • Groundwater hydrograph generally reflects response to weather
  • No indicated nearby pumpage and likely to remain uninfluenced by pumpage or changes related to human activities
  • Minimum period of record is 10 years of continuous/monthly records
  • Minimally affected by irrigation, canals, drains, pipelines, and other potential sources of artificial recharge
  • Well has casing – dug wells are generally not used
  • Water levels show no apparent hydrologic connection to nearby streams
  • Well has never gone dry
  • Long-term accessibility likely, such as on public land

In the Maryland, Delaware, and District of Columbia region, it is useful to compare current data to historical data, such as data from the droughts of 2002 and the 1960s. There are 11 wells that have over 60 years of groundwater data, and 23 wells have more than 30 years of groundwater data as of 2017.

November 2018 Groundwater Levels

Groundwater levels were at record November highs at 18 of 28 wells, above the 90th percentile at 9 wells, and within the 76th-90th percentile range at one well. Between October and November, groundwater levels increased at all of the wells included in this report.



Click here to access the clickable groundwater map.

In the 5-year hydrographs for the selected wells, groundwater levels are shown as a dark blue line. Each monthly measurement is colored according to the percentile rank compared to the historical values at the site for the month. The normal range is displayed as a white band and is based on the period of record. The maximum water level is at the top of the upper blue section, and the minimum water level is at the bottom of the lower blue area in the graph. The two wells in Harford County that set all-time record highs are featured below.


The groundwater level at observation well BA Ea 18 in Baltimore County, Maryland, was 14.41 feet below land surface, which is a November record high. The previous record was 16.77 feet below land surface in 1979. Monthly record-keeping at this well began in November 1956.

The groundwater level at USGS observation well WA Ci 82, in Washington County, Maryland, was 28.34 feet below land surface, which is a November record high. November was the fourth consecutive month with record highs. The previous record was 36.51 feet below land surface in 1996. Monthly record-keeping at this well began in February 1978.

Click here to view five-year groundwater hydrographs for other wells.

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