August Hurricanes Raise Water Levels in Southern Maryland

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

Jump to archives >>

Updated: September 3, 2004

Rainfall from Hurricanes Bonnie and Charley in August caused water levels to rise in Maryland. Streamflow levels in southern Maryland are above normal and an observation well in Charles County is at its highest August level since 1979 according to hydrologists at the U.S. Geological Survey (USGS). In other areas of Maryland and Delaware, August water levels were normal to above normal. Total freshwater flow to the Chesapeake Bay was more than twice the normal amount for August.

Status of Streams and Wells

The map below shows the location of the wells and streams used by the USGS to monitor water conditions in Maryland, Delaware, and the District of Columbia. In July, water levels were normal in western Maryland, normal to above normal in the Piedmont and southern Maryland regions. Water levels ranged from below normal to above normal in eastern Delaware.

Precipitation

Rainfall in August ranged from below normal to above normal across Maryland and Delaware. Rainfall was 3.74 inches, or 1.03 inches below normal, at Baltimore-Washington International (BWI) Airport, and only 2.30 inches (second consecutive month) at Hagerstown, Maryland, according to preliminary rainfall data from the National Weather Service. However, summer rainfall was above normal and temperatures were not excessive in August. Rainfall in Wilmington, Delaware was 1.82 inches above normal (5.33 total inches), and has been above normal for several months. In Somerset, Wicomico, and Worcester Counties, Maryland, August rainfall was nearly 3 times normal. Rainfall at Washington D.C. was 1.65 inches above normal, with 5.09 inches.

Chesapeake Bay

Monthly mean streamflow into the Chesapeake Bay during August averaged 46.2 bgd (billion gallons per day), which is 113 percent above normal. Flow has been above normal for the last 2 months: See graph at http://md.water.usgs.gov/monthly/bay.html. The Susquehanna, Potomac, and James Rivers are the largest rivers in the Chesapeake Bay watershed and usually contribute about 90 percent of the freshwater streamflow to the Bay (see table below). In an average year, approximately 50 percent of the freshwater flow comes from the Susquehanna River, 25 percent from the Potomac River, and 15 percent from the James River. The remaining 10 percent comes from surrounding tributaries and smaller streams. This August, more freshwater entered the Bay from the Susquehanna River (68 percent) than normal, while the Potomac and James Rivers contributed less water than normal. The Potomac River contributed 10 percent, the James River 8 percent, and 14 percent was from other sources in August. More information about USGS studies to help with the protection and restoration of the Chesapeake Bay and its watershed can be found at http://chesapeake.usgs.gov.

Streamflow

Streamflow in Maryland and Delaware ranged from normal to above normal levels in August. Rainfall in western Maryland was below normal and although streamflow levels rose, they were at normal levels. Streamflows in the central Maryland Piedmont region were normal to above normal. Southern and eastern Maryland received more than double the normal rainfall and streams responded with large increases, such as on the Pocomoke River (see hydrograph below). Current and historical streamflow data can be monitored on the web at: http://waterdata.usgs.gov/.

Five-year hydrograph of monthly mean streamflow on the Pocomoke River shows streamflow was below normal in July (orange) and above normal (blue) in August. The large increase in flow was in response to rainfall associated with Hurricanes Bonnie and Charley. Normal monthly mean flow is shown by the white band. Five-year monthly streamflow hydrographs from the USGS stream-gaging network can be viewed on the USGS website at: http://md.water.usgs.gov/surfacewater/streamflow/

Daily streamflow on the Potomac River near Washington, D.C. averaged 3.3 bgd in August, which is 24 percent above normal for the month of August. More information on the Potomac River is available at: http://md.water.usgs.gov/monthly/poto.html.

Groundwater-Unconfined or Shallow Aquifers

Abundant rainfall throughout the summer caused groundwater levels to rise in many of the wells used by the USGS to monitor unconfined or shallow aquifer response to climatic conditions in the bi-state region. Groundwater levels were in the normal to above normal range during August, and the observation well in Charles County reached the highest August level since 1979. For 5-year hydrographs of groundwater levels for the climatic indicator wells, visit: http://md.water.usgs.gov/groundwater/.

Groundwater-Confined or Deep Aquifers

Water levels in the deep confined aquifers continue to decline because the wells are pumped at higher rates than the rate at which deep groundwater is recharged. Because confined aquifers are deep, water levels in confined aquifers respond slowly to climatic conditions. The network of confined aquifer wells has been reduced because of diminishing funds. Several wells will no longer be measured on a monthly basis and the web pages will be updated when data is collected. Limited data for confined aquifer wells can be viewed at: http://md.water.usgs.gov/groundwater. Real-time water-level data can be viewed at: http://waterdata.usgs.gov/md/nwis/gw

Reservoir Storage

Storage of the Baltimore reservoir system dropped 2 percent, to 96 percent of capacity in August. 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 serves Montgomery and Prince Georges Counties, dropped 7 percent to 89 percent of capacity in August.

Water Monitoring

The USGS has been collecting National streamflow data for 120 years, since 1884. Streamflow monitoring began in Maryland on the Potomac River at Point of Rocks, Maryland in 1895 and continues today. 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 District of Columbia, visit Water Watch at: http://water.usgs.gov/waterwatch/.

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, Baltimore County, Baltimore City, and other agencies. The long-term observation wells used in this analysis are operated in cooperation with the Maryland and Delaware Geological Surveys and the Interstate Commission on the Potomac River Basin. The real-time wells are operated in cooperation with the Maryland and Delaware Geological Surveys, the Interstate Commission on the Potomac River Basin, and Calvert County, Maryland. The USGS publishes data for 137 streamflow stations, 393 observation wells, and 4 springs across Delaware, Maryland, and the District of Columbia.

The USGS serves the Nation 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 enhance and protect our quality of life.

** * 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