Drought Continues to Build

The water year runs from October 1 to September 30^th. Thanks to a very wet December and January in the 2023- 2024 water year, last year was only about an inch of rainfall short of the average here in Haymarket despite and extremely dry spring and summer. This year is shaping up differently. Despite the rain this past weekend, where I got under an inch of rain in my gauge, we are still 6 inches of rain behind normal. Not only Haymarket, but the entire Potomac River watershed has had a dry winter.

from CoCoRHaS 5.5 N Haymarket, VA

Virginia generally receives about 44 inches of precipitation per year in Prince William County and over 40 inches in all of the Commonwealth and is historically considered “water rich" area. However, droughts are not uncommon, Virginia has a history of multi-year droughts. The climate forecasts for the region call for longer and more sever droughts and wetter non-drought years. The graph below shows the frequency of drought years since 2000. As you can see, so far the droughts we have seen have been very mild by historical standards. 

 

from NOAA

Below is the groundwater picture at USGS monitoring well 49V in the Northwest corner of Prince William County.  It is clear from the first USGS graph that the groundwater level in well 49V  has falling for 15 or more years. The groundwater is being used up. In the second graph you can see that for decades before that the groundwater level was fairly stable, but the monitoring was not continuous in those days (thus the little circles). The PW BOCS has recently approved the funding to begin groundwater studies and monitoring. 

from USGS

Virginia is dependent on groundwater. According to information from Virginia Tech, the Rural Household Water Quality program and the National Groundwater Association approximately 30% of Virginians are entirely dependent on groundwater for their drinking water. In Prince William County about a fifth of residents get their water directly from groundwater, including the Evergreen/Bull Run distribution system. However, the health of our watersheds and stream flow are dependent on groundwater, too.  Groundwater provides the baseflow to the rivers and streams. While groundwater is ubiquitous in Virginia it is not unlimited. There are already problems with availability, quality and sustainability of groundwater in Virginia in places such as Fauquier County, Loudoun County and the Coastal Plain. 

from ICPRB

After weeks of frigid temperatures, ice is now breaking up in the river and we are able to see the flow on USGS gages. The blue block on the graph below indicates no data due to ice. The flow (blue line) at Point of Rocks is 3,330 cubic feet per second (cfs). The median (gray line) for this time of year is 8,500 cfs. We are currently at less than 40% of median flow.

 

Last week’s U.S. Drought Monitor map for the Potomac River basin shows 75% of the area is in Moderate Drought conditions and 12% is in Sever Drought (mostly the south eastern section of the watershed which includes the eastern portion of Prince William county). This is an increase in Moderate Drought conditions over last week’s map.

 

The DC metropolitan area remains in the Drought Watch declared by the Metropolitan Washington Council of Governments (COG) back in July. Officials are asking everyone to use water wisely during this time. The COG Drought Coordination Technical Committee will convene on March 7 to evaluate the drought declaration.