2002: A Record-Setting Year for Low Groundwater Levels Water Levels Recover to Normal in December 2002

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: January 7 , 2003

Above normal amounts of rain and snow during the past 3 months have brought groundwater and streamflow levels back to normal and above normal levels, ending the region's worst hydrologic (groundwater and streamflow levels) drought on record, according to hydrologists at the U.S. Geological Survey (USGS) in Baltimore. A water-supply drought still exists in Maryland and water restrictions are still in place because reservoir levels in the Baltimore area remain below the normal levels needed to meet the water-use demands for next summer.

Recovery from severe hydrologic drought conditions has been quicker than expected. In September 2002, many wells and streamflow stations were setting all-time record lows; by December, most of the stations had returned to normal or above normal levels. The quick recovery is a function of the timing and nature of the precipitation. The rain has been steady and gradual and there have been several moderate snowfalls that have melted slowly, allowing aquifers to recharge. During this time of year, water demand is low and we typically get the recharging rains and snows that increase water levels sufficiently to get us through the following summer. Recharge did not occur in 2001 because the weather was unusually dry and warm, resulting in record-setting low groundwater and streamflow levels.

Groundwater is the last hydrologic element to recover from drought conditions because it takes a number of months to recharge aquifers. Groundwater levels have increased across Maryland and Delaware, many to normal levels and some to above normal levels at the end of December (see graphs at http://md.water.usgs.gov/groundwater/.) Streams continued to flow at normal to above normal levels at the end of December, which indicates that groundwater recharge has occurred, but streamflow can fall off quickly during periods of no rainfall. Groundwater keeps streams flowing between rain events. To keep groundwater and streamflow at normal levels, we need more recharge to get us through next summer. This means several more months of normal to above normal precipitation are necessary.

In September 2002, 9 of the 16 wells used by the USGS to assess water resources across Maryland and Delaware set monthly record lows; 7 were all-time records (shown in orange in the table to the right). This table shows how water levels have responded to precipitation and increased over the last 3 months. Rising water levels indicate that aquifers are being recharged and the hydrologic drought has ended. The largest increase was in Carroll County (10.26). Only two of the nine wells had below normal levels at the end of December.

Water levels in a deep, bedrock well in Baltimore County, Maryland dropped for 15 months until they finally responded to precipitation and began to rise in mid-November. The groundwater level remains below normal, but the water level has risen about a foot in the last month and continues to rise, indicating the bedrock aquifer is being recharged.

The 5-year hydrograph above shows the groundwater level as depth below land surface for a deep (250 feet), bedrock well in Baltimore County, Maryland. Water levels typically follow a seasonal variation, reaching their lowest point in late fall and their highest levels in early summer. Because the well is deep and the water source is from a bedrock aquifer, response to precipitation is slow. For example, during the drought of 1999, the groundwater level did not drop much below normal, while other nearby wells were setting record monthly lows. The response in the well to Hurricane Floyd was a slow rise to normal levels. The water levels remained at normal levels until late 2001.

For 15 months, starting in the summer of 2001, the water levels in this well dropped because of the abnormally warm and dry winter (when recharge typically occurs). After several weeks of normal rainfall, the water level began to rise in mid-November 2002. In the last 3 months in 2002, the water level has rose 1.66 feet and continues to rise, indicating that recharge is finally occurring.

The abundant rain and snow have led to above normal streamflows, which in turn have helped to refill reservoirs slightly, but not enough to lift the water restrictions in the area served by the reservoirs. Storage in the Baltimore Reservoir System increased 7 percent to 59 percent of capacity at the end of December, and the contents of the Triadelphia and Duckett Reservoirs on the Patuxent River increased 23 percent to 80 percent of capacity. Reservoirs in the region are typically about 90 percent of capacity at this time of year.

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

Streamflows during the last 7 days of December and monthly streamflow ranged from normal to above normal at streamflow stations across Maryland and Delaware. Piscataway Creek in Maryland set a monthly record high in December. All 30 stations used to monitor average monthly streamflow conditions by the USGS were normal to above normal. Five-year monthly streamflow hydrographs can be viewed on the USGS website at: http://md.water.usgs.gov/surfacewater/streamflow/.

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/

Average monthly streamflow at the Potomac River near Washington, D.C. was at 44 percent above normal (see graphs at http://md.water.usgs.gov/monthly/poto.html. Total flow into the Chesapeake Bay during December averaged 64.6 bgd (billion gallons per day), which is 23 percent above average. During 2002, total streamflow into the Chesapeake Bay was 24 percent below average. More information about water and the Chesapeake Bay can be found at: http://chesapeake.usgs.gov/.

Was the hydrologic drought of 2002 worse than the 1960s drought?

In 2002, the drought was so severe that water restrictions were in place for most of the year in Maryland and many new domestic wells drilled. In some communities, water was hauled into their region to meet water supply needs, as many reservoirs reached very low levels. Delaware also experienced the strain of drought conditions. During the 2002 drought, it was possible to monitor groundwater and streamflow conditions using real-time data. This technology enabled managers of water-supply operations to make timely decisions.

Groundwater

Since the USGS began measuring wells in Maryland and Delaware, never before has there been so many wells breaking monthly record lows for such a long time. The number of monthly record lows exceeded those set during the 1960s drought. The graph at the right shows the number of monthly record low groundwater levels that were set for the 16 wells the USGS uses to track water conditions. More than twice the number of records were set in 2002 than 1966. In 2002, 72 monthly record lows were set, while in 1966, only 32 monthly record lows were set. The water levels ranged from 1 to 6 feet below normal levels and many exceeded the previous record by about 1 foot.

Streamflow

Streamflow also showed the effects of the hydrologic drought. Many daily low streamflow and average monthly streamflow records were set across Maryland and Delaware. Streams respond to climatic conditions more quickly than groundwater levels. This is because runoff will readily flow down slope until it reaches a low spot, such as a creek or river. Groundwater contributes much of the flow to streams, called baseflow, between rain events. Since groundwater levels were low, so were streamflow levels. Groundwater recharge occurs more slowly because of the time it takes for water to infiltrate through the grains of sediment or through the cracks or fractures in the bedrock.

At Deer Creek in Harford County, Maryland, the monthly streamflow was at record lows for more than a year (see 5-year hydrograph above). Streamflow was below normal from August 2001 to November 2002 and set 8 consecutive new monthly record lows. Notice that streamflow was also below normal during the drought of 1999. By October 2002, the streamflow in Deer Creek returned to normal levels because of the abundant rainfall during the fall.

Deer Creek also set daily record lows for more than half the year (206 days) in 2002, and 18 days in September 2002 at the end of the water year (October 1 through September 30). Other streams that set daily record lows are shown in the graph below, such as the Potomac River, which set new daily record lows for 72 days during 2002.

Flow in the Potomac is regulated by reservoir releases to maintain a minimum flow over the dam at Little Falls near Washington, D.C. to ensure habitats are preserved downstream. For calendar year 2002, the flow on the Potomac River was 64 percent below average. Preliminary calculations of lowest natural daily flow (without diversions) done by the Interstate Commission on the Potomac River Basin (ICPRB) show that the lowest streamflow of the year was 546 cfs (cubic feet per second) on September 19, 2002. This low flow value was approximately as extreme as the low daily flow of 543 cfs set on September 10, 1966.

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 climate is affecting streamflow and groundwater levels in Maryland and Delaware, see Drought Watch at: http://md.water.usgs.gov/drought/. Additional groundwater levels, streamflow, and water-quality data can be obtained from the USGS National Water Information System Web site (NWISWeb) at http://waterdata.usgs.gov/nwis/.

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