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January 2005 Water Levels Normal to Above Normal

U.S. Department of the Interior
U.S. Geological Survey

Wendy McPherson (
Maryland-Delaware-D.C. Water Science Center
5522 Research Park Drive
Baltimore, MD 21228
FAX: (443)498-5510

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Updated: February 7, 2005

Rainfall in the middle of January led to high streamflows in northern Maryland and northern Delaware, according to hydrologists at the U.S. Geological Survey (USGS). Monthly water levels, however, were normal to above normal across Maryland, Delaware, and Washington, D.C., continuing the several-month-long trend of normal to above normal water levels.

Status of Streams and Wells

The map below shows the location and status of wells and streams used by the USGS to monitor water conditions in Maryland, Delaware, and Washington, D.C. for January 2005. Water levels were generally above normal in the northern parts of Maryland and Delaware, and normal in southern Maryland and most of the Delmarva Peninsula.


January precipitation and temperatures were close to long-term averages in Maryland and Delaware, and Washington, D.C., according to preliminary rainfall data from the National Weather Service (NWS). However, temperatures at the beginning of the month averaged about 10 degrees warmer than normal and New Year’s Day was the warmest on record at 67 degrees (from NWS statement). On January 13 and 14, 1 to 2 inches of rain fell on the region, resulting in high streamflow levels. The last half of January was about 10 degrees colder than normal and included several snowfalls.

Chesapeake Bay

Monthly mean streamflow into the Chesapeake Bay during January averaged 103 bgd (billion gallons per day), which is 80 percent above normal. Normal flow for January is 57.4 bgd.


Streamflow increased and was normal to above normal in streams in Maryland, Delaware, and Washington, D.C. in December. Streamflow was normal to above normal throughout 2004, except for the Choptank River, Nassawango Creek, and the Pocomoke River, which were below normal during the summer. The hydrograph of Piscataway Creek shows that streamflow levels did not follow the typical seasonal pattern because of abundant rainfall and groundwater levels.

Current and historical streamflow data can be monitored on the web at: Five-year monthly streamflow hydrographs from the USGS stream-gaging network can be viewed on the web at:

Daily streamflow for the Potomac River near Washington, D.C. averaged 12.6 bgd in January, which is 39 percent above normal. More information on the Potomac River is available at:


Near normal precipitation in January led to normal to above normal water levels in wells used by the USGS to monitor unconfined or shallow aquifer response to climatic conditions in Maryland and Delaware. Groundwater levels in southern Maryland and on the Delmarva Peninsula were at normal levels.

Recharge to the groundwater system typically occurs late fall to early spring when water levels rise because of low evapotranspiration (water that evaporates or is used by plants) rates. The highest groundwater levels are typically in March or April before the growing season begins. For 5-year hydrographs of groundwater levels for the climatic indicator wells, visit:

Reservoir Storage

Storage in the Baltimore reservoir system rose 1 percent to 100 percent of capacity in January. The Baltimore reservoirs (Loch Raven, Liberty, and Prettyboy) have been nearly full since May 2003. Storage in the Triadelphia and Duckett Reservoirs on the Patuxent River, which serve Montgomery and Prince Georges Counties, rose 7 percent to 100 percent of capacity in January.

U.S. Geological Survey

Streamflow and groundwater levels are used to assess current water conditions and can be used to predict the potential for flooding and drought conditions. These USGS data have been provided to State and local water resource managers and are critical for making appropriate decisions on water regulation. For more information on streamflow and groundwater levels in Maryland, Delaware, and the Washington, D.C., visit Water Watch at: Water Watch.

The USGS, a Bureau within the Department of the Interior, has served the Nation and the world for 125 years by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and make important decisions and enhance and protect our quality of life.

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In-depth information about USGS programs may be found on the USGS home page at and for Chesapeake Bay activities.

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