Sunday, July 7, 2024

DEQ Issues Drought Warning for Northern VA

Last week, the Virginia Department of Environmental Quality issued a drought warning advisory for our area. A drought warning advisory indicates a significant drought is imminent for the Northern Virginia Region which includes Fauquier, Loudoun, Prince William, Arlington, and Fairfax counties and for the Shenandoah region, which includes Augusta, Rockingham, Shenandoah, Frederick, Page, Warren, and Clarke counties. Fauquier County WSA water systems have already implemented Mandatory Outdoor Water Usage Restrictions for their customers.

from DEQ 

Virginia generally receives 44 inches of precipitation each year and is historically considered “water rich." However, droughts are not uncommon, and Virginia has a history of multi-year droughts, including the record-breaking droughts of 1999–2002, 2007–2008, and 2010–2012. Virginia also experienced a short, high-impact drought during the late summer and fall of 2023 that was a primary factor in several major wildfires, including the Matts Creek Fire in the Jefferson National Forest; and the seasonal drying out of what had been perennial streams.

Droughts in Virginia can have far-reaching impacts on agriculture, water availability, and wildfires. Drought conditions can also develop rapidly, especially when the lack of rain and high temperatures combine to quickly increase the loss of water from the landscape via evapotranspiration. There is increased regional awareness of how these rapid-onset droughts, sometimes referred to as "flash droughts," can cause significant agricultural economic impacts and supply concerns to other water users-residential, commercial and industrial.

Flash drought is simply the rapid onset or intensification of drought. It is set in motion by lower-than-normal rainfall , accompanied by abnormally high temperatures, winds, and radiation. Together, these changes in weather can rapidly alter the local climate. Higher temperature increases evapotranspiration—the process by which water is transferred from the land to the atmosphere by evaporation from the soil and by transpiration from plants—and further lowers soil moisture, which decreases rapidly as drought conditions continue.

If not predicted and discovered early enough, changes in soil moisture that accompany flash drought can cause extensive damage to agriculture, economies, and ecosystem goods and services. Though Virginia now has a Water Resource Plan that is compiled every 5 years, it is still early in the process. Virginia is projecting an 18% increase in water use There is no forecast of a growing need for water to cool data centers. Dominion Power and PJM were caught flat footed by the surge in demand for electric power. While data centers use relatively less cooling water than power, the water use the Washington Post reports that a large data center uses between 1 million and 5 million gallons of water a day for cooling. That is as much water as a town of 10,000 to 50,000 people. That water use does not appear to be counted in the water use projections. In addition, that water use cannot be reduced during drought. 

Data centers that obtain their water from Public Supply may have back up groundwater wells. In Virginia there are not regulations on that outside the Potomac Aquifer Groundwater Management Area. The Virginia Water Withdrawal Reporting Regulation only requires the registration and annual reporting of surface water and groundwater withdrawals of any entity withdrawing more than 300,000 gallons per month. A backup well might not trip the reporting requirement. There is no control or management of the water withdrawals except in the Groundwater Management areas of Virginia. This may impact our ability to respond to drought in the future. The data center need for cooling water will become part of the “base” need that we will need to have adequate water storage to supply.

Following the guidance in the Virginia Drought Assessment and Response Plan, the Virginia Drought Monitoring Task Force (DMTF) monitors and evaluates hydrologic and water supply conditions for DEQ .  The DMTF is also responsible for making recommendations for Drought Stage declarations.  These declarations are intended to facilitate communities’  preparation for a drought. Drought warning responses are called for when the onset of a significant drought event is imminent.

DEQ uses the indicators listed below to gauge the presence and severity of hydrologic drought across the 13 Drought Evaluation Regions.  According to the Virginia DMTF, a work group of state and federal agencies coordinated by DEQ, the primary factors contributing to the advisory are low precipitation across the state over the past 90 days, low stream flows and low groundwater levels compared to previous levels for this time of year.

Each day, DEQ compares groundwater levels and streamflow records from “real-time” continuous recording wells and gaging stations across Virginia to long-term records (at least 10 years) for the current month.  For groundwater, daily records are compared; for streamflows, the average of the previous seven days’ flow records are compared.

A drought warning indicates that a drought is imminent. So local governments and and water utilities are advised to implement restrictions on water use- both voluntary and mandatory.  Rainfall deficits, high temperatures and high outdoor water use have contributed to the increasing drought warning signs. Drought Indicators tracked by DEQ (and key to Drought Map) are:

  • Precipitation (Prcp)
  • Groundwater Levels (GW)
  • Streamflow (Flow)
  • Reservoir Levels (Res)
According to the DEQ drought indicator map for July 7th 2024 the USGS Groundwater monitoring well 49V 1 is at emergency state. The water level is a few feet below last July and the lowest level in years.  

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