April Showers Not Enough to Raise Groundwater Levels
U.S. Department of the Interior
U.S. Geological Survey
Wendy McPherson (email@example.com)
Maryland-Delaware-D.C. Water Science Center
5522 Research Park Drive
Baltimore, MD 21228
Updated: May 2 , 2002
Record low groundwater levels for April were set at seven water-table wells in central Maryland, according to hydrologists at the U.S. Geological Survey (USGS). Above normal rainfall in April helped raise streamflow levels in parts of Maryland, yet more than half of the real-time streamflow stations still had below-normal streamflow across Maryland and Delaware at the end of April. Streamflow and groundwater levels are reflecting the lack of precipitation last fall and winter.
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April was the first month since August 2001 with above normal rainfall at Baltimore-Washington International (BWI) Airport, according to the National Weather Service. Most of the rain that falls at this time of year is used by plants (evapotranspiration) or evaporates. However, much of the rain during extreme events, such as thunderstorms, may run off and cause flooding, and will not contribute significantly to groundwater recharge. Groundwater levels reflect the long-term effects and the severity of the hydrologic drought and generally take a long time to respond to precipitation events.
Groundwater levels were below normal near month's end at seven wells used for drought analysis in Maryland and Delaware. Record low groundwater levels were set in Baltimore, Carroll, Harford, Montgomery, and Prince Georges Counties in Maryland, and Kent County in Delaware (see graphs at http://md.water.usgs.gov/groundwater/). The record for the well in Harford County exceeded the previous April record low set in 1981 by 2.37 feet.
Total flow into the Chesapeake Bay averaged 94.1 bgd (billion gallons per day), which is 43% below average flow into the Bay during April. Streamflow on the Potomac River increased to normal monthly levels after 6 months of below-normal flow. This is largely due to the abundant rainfall in the upper parts of the drainage basin.
Streamflow at Deer Creek in Harford County, Maryland, was the lowest April flow for the period of record. Deficits in streamflow and groundwater remain in central Maryland and Delaware. Above-normal rainfall is needed through the spring and summer to replenish low streamflow and groundwater levels.
Storage in the Baltimore reservoir system increased 3 percent to 62 percent of capacity in April. The Baltimore region has been supplementing the water supply with water from the Susquehanna River since the end of January.
Tracking streamflow and groundwater levels is essential to gauge drought severity and recovery. These USGS data have been provided to State and local water resources managers and are critical for making appropriate decisions on water restrictions. For more information on how the drought is affecting streamflow and groundwater levels in Maryland and Delaware, see Drought Watch at: http://md.water.usgs.gov/drought/.
The real-time streamflow stations used in this analysis are operated in cooperation with the Maryland and Delaware Geological Surveys, the Maryland State Highway Administration, the U.S. Army Corps of Engineers, the Maryland Department of Natural Resources, the Maryland Department of the Environment, and other agencies. The observation wells used in this analysis are operated in cooperation with the Maryland and Delaware Geological Surveys. The USGS publishes data for 128 streamflow stations and 379 wells across Maryland and Delaware.
The U.S. Geological Survey is the Nation's largest water, earth and biological science, and civilian mapping agency providing reliable, impartial scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation and the economic and physical development of the Nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources.
** * USGS * * *
- 01-06-2006 Water Resources Plentiful at End of December 2005; Chesapeake Bay Flow Normal in 2005
- 07-06-2005 Water Levels Fall as Summer Arrives
- 04-06-2005 March 2005 Water Levels Near Normal
- 03-04-2005 Flow Below Normal in Potomac River and Chesapeake Bay
- 02-07-2005 January 2005 Water Levels Normal to Above Normal
- 01-07-2005 2004 Ends with Normal to Above Normal Water Levels
- 12-04-2004 Water Levels Remain Generally Above Normal
- 11-04-2004 Dry October Causes Water Levels to Drop
- 10-06-2004 Highest September Flow to the Chesapeake Bay Since 1937
- 09-03-2004 August Hurricanes Raise Water Levels in Southern Maryland
- 08-06-2004 Localized Flooding in Northeastern Maryland and Delaware in July
- 07-07-2004 Water Levels Normal to Above Normal in June
- 06-04-2004 Streams Return to Normal Levels in Maryland and Delaware during May 2004
- 05-06-2004 Streams Rise to Above Normal Levels in Maryland
- 04-07-2004 Streamflow and Groundwater Levels Fell in March 2004
- 03-04-2004 Streamflow and Groundwater Levels Normal to Above Normal in February 2004
- 02-04-2004 Cold, Dry January Leads to Drop in Water Levels
- 01-06-2004 Wettest Year Leads to Record-High Water Levels Including Third Highest Flow to Chesapeake Bay in December and 2003
- 12-04-2003 More Record-High Water Levels in November 2003
- 11-04-2003 Record High Groundwater Levels in October 2003
- 10-03-2003 Flow to Chesapeake Bay in Water Year 2003 Second Highest Since 1937
- 09-05-2003 Third Consecutive Month of High Flow into the Chesapeake Bay
- 08-06-2003 Flow into Chesapeake Bay near Record High Levels
- 07-07-2003 Record Breaking High Water Levels in Maryland and Delaware
- 06-06-2003 Streamflow and Groundwater Levels High in May
- 05-07-2003 April Water Levels Normal
- 04-05-2003 Water Levels High in March - Water Restrictions Lifted
- 03-05-2003 Exceptionally Wet February Leads to High Water Levels
- 02-06-2003 Maryland and Delaware Streamflow and Groundwater Levels Remain Normal in January 2003
- 01-07-2003 2002: A Record-Setting Year for Low Groundwater Levels - Water Levels Recover to Normal in December 2002
- 12-01-2002 Hydrologic Drought Wanes as Water Levels Rise
- 11-01-2002 Water Levels Rise Across Maryland and Delaware, But Drought Persists in Some Areas
- 10-03-2002 Water Levels Remain at Record-Setting Lows
- 09-05-2002 Groundwater in Parts of Maryland Reaches Lowest Levels Since 1962, Despite Late August Rains
- 08-06-2002 Drought Conditions Lead to 10 Record Low Monthly Groundwater Levels in July
- 07-03-2002 Record Low Water Levels Show the Effects of Long-Term Hydrologic Drought
- 06-04-2002 Groundwater Levels Reflect Long-Term Effects of Drought
- 05-02-2002 April Showers Not Enough to Raise Groundwater Levels
- 04-05-2002 The Drought in Full Bloom: Low Water Levels Result in Water Restrictions
- 12-03-2001 Record Low Water Levels Set in November
- 11-02-2001 Dry October Leads to Low Water Levels
- 10-05-2001 Water Levels Low in Northern Maryland
- 09-07-2001 Water Levels Stable in August
- 08-06-2001 High and Low Water Levels in July
- 07-06-2001 Water Levels Continued to Improve in June
- 06-06-2001 Needed Rain Helps Avert a Drought in May
- 05-08-2001 Water Levels Still Normal in April, but More Rain is Needed
- 04-05-2001 Spring Rains Help Water Levels
- 03-06-2001 Water Levels Improve, But Are Still Below Normal
- 02-06-2001 Streamflow Still Low in Maryland in January
- 01-05-2001 Streamflow to Chesapeake Bay in 2000 Reflects Dry Autumn
- 12-05-2000 Streamflow in Maryland Beginning to Show the Effects of Lack of Rain
- 11-07-2000 Despite Lack of Rain October Water Conditions near Normal
- 10-06-2000 September Water Conditions Above Normal in Maryland, Delaware, and D.C.
- 09-08-2000 August Water Conditions Above Normal in Maryland, Delaware, and D.C.
- 08-07-2000 July Water Conditions Continue Normal in Maryland, Delaware, and D.C.
- 07-07-2000 June Water Conditions Normal in Maryland, Delaware, and D.C.
- 06-06-2000 Water conditions begin to decline in Maryland, Delaware, and D.C.
- 05-05-2000 Water Conditions Continue to Improve in Maryland, Delaware, and D.C.
- 04-07-2000 Water Conditions Continue to Improve in Maryland, Delaware, and D.C.
- 03-07-2000 Water Conditions Improving in Maryland, Delaware, and D.C.
- 02-08-2000 January Streamflow and Groundwater Levels Still Low
- 01-06-2000 1999 Flow Into Chesapeake Bay Lowest Since 1960s Drought