Groundwater in Parts of Maryland Reaches Lowest Levels Since 1962, Despite Late August Rains

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

Contact:
Wendy McPherson (wsmcpher@usgs.gov)
Maryland-Delaware-D.C. Water Science Center
5522 Research Park Drive
Baltimore, MD 21228
Phone:(443)498-5500
FAX: (443)498-5510

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Updated: September 5, 2002

Streamflow and groundwater levels continued to decline in August across Maryland and Delaware, setting many daily, monthly, and all-time record low levels. Rain at the end of August helped to improve soil moisture, and streamflow rose temporarily, yet groundwater levels showed little response to the rain. All of the 17 wells used for drought analysis in Maryland and Delaware had below normal water levels at the end of August, according to hydrologists at the U.S. Geological Survey (USGS). Nine of the wells set record low groundwater levels for August and four of these wells set all-time record low levels (since record-keeping began in 1962). More than half of the streams used to monitor drought conditions had below normal flow at the end of August, despite several inches of rain at the end of the month.

For news release and images, visit:
http://md.water.usgs.gov/publications/press_release/current

In Maryland, wells in Baltimore, Harford, Montgomery, and Queen Annes Counties reached the lowest level since record-keeping began in 1962 (see attached table), breaking the records set during the 1966, 1981, and 1999 drought years. These wells and five additional wells from Charles, Carroll, and Somerset Counties, set record lows for August.

The drought monitoring well with the largest deficit from normal is in Carroll County, Maryland. The groundwater level at this well was 7.74 feet below normal for August, surpassing the previous August record set in 1999 by 1.92 feet. The monitoring well in Harford County, Maryland is 7.16 feet below normal for August, and exceeded the previous record low of 16.38 feet set in August 1981. In Baltimore County, Maryland, the 5-year hydrograph shows that the groundwater level has been dropping since summer 2001, indicating that rainfall has not recharged the groundwater system (see graphs and a record comparison table at http://md.water.usgs.gov/groundwater/).

Detailed ground water data is available at:
http://md.water.usgs.gov/groundwater/

Recent abundant rainfall on the lower Eastern Shore of Maryland caused record daily high streamflow and some recovery of groundwater levels. The Pocomoke River on the Eastern Shore went from having its lowest 7-day streamflow at the end of August to setting daily record highs as a result of the rain that fell on the region. The groundwater level in the real-time well, located in Kent County, rose by about a half a foot in response to the rainfall. Real-time groundwater levels and streamflow are monitored by the USGS across the Nation at 15-60 minute intervals and the data are transmitted via satellite to USGS offices every 1 to 4 hours. This information can be viewed within minutes of arrival at: http://waterdata.usgs.gov/.

Ground-Water Levels in the Metropolitan Washington D.C. Area can be seen at http://md.water.usgs.gov/groundwater/web_wells/current/water_table/counties/cog/

Except for western Maryland, where streamflow was normal at the end of August, streamflow was below normal across Maryland and Delaware. Record low monthly streamflows were recorded at Antietam Creek, Deer Creek, and Pocomoke River in Maryland, and Brandywine Creek in Delaware. Each of these sites also set new daily lows for more than 20 days in August. The Potomac River near Washington, D.C. also set several new daily record low flows, and monthly streamflow was only 52 percent of normal (see graphs at http://md.water.usgs.gov/monthly/poto.html. Streamflow on the Choptank River near Greensboro, Maryland was 85 percent below normal. Five-year streamflow hydrographs can now be viewed on the USGS web: http://md.water.usgs.gov/surfacewater/streamflow.

Five-year streamflow hydrographs can now be viewed at:
http://md.water.usgs.gov/surfacewater/streamflow

Average streamflow at Deer Creek in Harford County, Maryland, was the lowest monthly August flow for the period of record at 79 percent below normal. Streamflow at Deer Creek has been below normal for 15 of the last 16 months, and set daily low streamflow records for 24 of the 31 days in August. This is the seventh consecutive month with record-setting monthly low streamflow for Deer Creek.

The Baltimore region has been supplementing its water supply with water from the Susquehanna River since the end of January. Streamflow on the Susquehanna River reached low levels that required Maryland water suppliers to reduce the amount of water withdrawn from the river and increased the amount of water withdrawn from reservoirs. One result was a 7-percent decline in storage of the Baltimore Reservoir System since July. Storage in the Baltimore reservoir system was 48 percent of capacity at the end of August and the contents of the Triadelphia and Duckett Reservoirs were at 51 percent of capacity.

Another result of the low Susquehanna River flow was the second lowest total flow into the Chesapeake Bay for August since 1964. Total flow into the Chesapeake Bay during August averaged 7.75 bgd (billion gallons per day), which is 64 percent below average. The lowest August total flow to the Bay for the period of record was 6.34 bgd in 1966 (see graphs at http://md.water.usgs.gov/monthly/bay.html.)

Although August rainfall was near normal across Maryland and Delaware, the average temperature was higher than normal, and the annual rainfall deficit from 5 inches below normal in Garrett County, Maryland to 16.80 inches below normal in Calvert County, according to the National Weather Service.

Rainfall from scattered thunderstorms may temporarily raise streamflow levels, but most of the rainfall in the summer is used by plants or evaporates, resulting in minimal recharge to groundwater aquifers. Only about 5 percent of the recent rain between August 28 and September 4 became runoff, or contributed water to streams. This indicates that more than 95 percent of the water was used by plants, evaporated, or remained in the soil and possibly recharged groundwater. The rapid decline in streamflows after a rainfall event is caused by the low groundwater storage. Streamflows in the summer normally are maintained by groundwater storage, which typically is highest in early spring, yet have been at record lows for many months in central Maryland. Streamflow and groundwater levels reflect the long-term effects and severity of the hydrologic drought, and generally do not recover during the summer months.

Tracking streamflow and groundwater levels is essential to gauge drought severity and recovery. These USGS data have been provided to State and local water resource 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/.

Please note that the streamflow and groundwater level data is provisional and subject to change.

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 USGS, a bureau within the Department of the Interior, 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 * * *

In-depth information about USGS programs may be found on the USGS home page at http://www.usgs.gov and http://chesapeake.usgs.gov/ for Chesapeake Bay activities.

Archived News Releases 2000-Present

2006

• 01-06-2006 Water Resources Plentiful at End of December 2005; Chesapeake Bay Flow Normal in 2005

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

2004

• 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

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

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

2001

• 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

2000

• 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 Ground Water Levels Still Low
• 01-06-2000 1999 Flow Into Chesapeake Bay Lowest Since 1960s Drought