Current Status of Virginia Drought Regions and Drought Indicators

Virginia Drought Regions

For the purpose of implementation of the Drought Response Plan, the Commonwealth has been divided into thirteen drought evaluation regions.  Regional boundaries generally correspond to regions of the Commonwealth that possess similar climatic, ground water, streamflow, and water supply conditions.  Towns and cities are only listed when they are on the boundary of a drought evaluation region. Drought evaluation regions include all towns and independent cities located within the region. 

Drought Evaluation Regions

  • Big Sandy Drought Evaluation Region:  Buchanan, Dickenson, Lee, Russell, Scott, Smyth, Tazewell, Washington, and Wise Counties; Bristol and Norton Cities.
  • New River Drought Evaluation Region:  Bland, Carroll, Floyd, Giles, Grayson, Pulaski,  Montgomery and Wythe Counties; Galax and Radford Cities.
  • Roanoke River Drought Evaluation Region:  Bedford, Campbell, Charlotte, Franklin, Halifax, Henry, Mecklenburg, Patrick, Pittsylvania and Roanoke Counties; Bedford, Danville, Martinsville, Roanoke and Salem Cities.
  • Upper James Drought Evaluation Region:  Alleghany, Bath, Botetourt, Craig, Highland, and Rockbridge Counties; Buena Vista, Covington and Lexington Cities.
  • Middle James Drought Evaluation Region: Albemarle, Amelia, Amherst, Appomattox, Buckingham, Chesterfield, Cumberland, Fluvanna, Goochland, Hanover, Henrico, Nelson, Powhatan, and Prince Edward Counties; Charlottesville, Colonial Heights, Lynchburg, Hopewell, Petersburg and Richmond Cities.
  • Shenandoah Drought Evaluation Region:  Augusta, Clarke, Frederick, Page, Rockingham, Shenandoah, and Warren Counties; Harrisonburg, Staunton, Waynesboro and Winchester Cities.
  • Northern Virginia Drought Evaluation Region:  Arlington, Fairfax, Fauquier, Loudoun and Prince William Counties; Alexandria, Fairfax, Manassas and Manassas Park Cities.
  • Northern Piedmont Drought Evaluation Region:  Culpeper, Greene, Louisa, Madison, Orange, Rappahannock, Spotsylvania, and Stafford Counties; Fredericksburg City.
  • Chowan Drought Evaluation Region:  Brunswick, Dinwiddie, Greensville, Lunenburg, Nottoway, Prince George, Southampton, Surry, and Sussex Counties; Emporia and Franklin Cities.
  • Northern Coastal Plain Drought Evaluation Region:  Caroline, Essex, Gloucester, King and Queen, King George, King William, Lancaster, Mathews, Middlesex, Northumberland, Richmond, and Westmoreland Counties.
  • York-James Drought Evaluation Region:  Charles City, James City, New Kent and York Counties; Hampton, Newport News, Poquoson and Williamsburg Cities.
  • Southeast Virginia Drought Evaluation Region: Isle of Wight County; Chesapeake, Norfolk, Portsmouth, Suffolk and Virginia Beach Cities.
  • Eastern Shore Drought Evaluation Region:  Accomack and Northampton Counties.

Drought Indicators

To monitor potential drought conditions in a uniform manner across the Commonwealth, Virginia uses four indicators to evaluate drought severity. The indicators are based on the amount of precipitation and the effect of the precipitation (or lack of) on the hydrologic system. 

Precipitation Deficits

Precipitation deficits will be monitored by comparing current precipitation amount with historical precipitation values as a percent of normal long-term average values.  Comparisons will be made for each drought evaluation region using data compiled by the Office of the State Climatologist. Normal long-term average precipitation is defined as the mean precipitation for a thirty-year period of record for the area and time period being evaluated.

Precipitation amounts will be evaluated based on the water year (beginning October 1).  Water years are a natural dividing point for water supply drought, as precipitation that falls in the first six months of a water year is analogous to putting money in the bank.  Precipitation that occurs during this six month period has the potential to recharge ground water, which will sustain stream flows and support withdrawals from wells during the following six month period when moisture deficits naturally develop as evaporation and plant transpiration generally exceed precipitation. If a precipitation deficit outside of the normal range exists at the end of a water year, the precipitation records will carry forward until a normal condition is reached (i.e. if a precipitation deficit exists on October 1, precipitation records for the previous twelve months will be evaluated until the twelve month deficit is eliminated).
 
Because the significance of a precipitation deficit changes as the water year progresses, drought response stages will trigger at different percentages of normal depending upon the date of evaluation.
 
 
Months Analyzed
Normal
(% of Normal Precipitation)
Watch
(% of Normal Precipitation)
Warning
(% of Normal Precipitation)
Emergency
(% of Normal Precipitation)
October-December
>75.0
<75.0
<65.0
<55.0
October-January
>80.0
<80.0
<70.0
<60.0
October-February
>80.0
<80.0
<70.0
<60.0
October-March
>80.0
<80.0
<70.0
<60.0
October-April
>81.5
<81.5
<71.5
<61.5
October-May
>82.5
<82.5
<72.5
<62.5
October-June
>83.5
<83.5
<73.5
<63.5
October-July
>85.0
<85.0
<75.0
<65.0
October-August
>85.0
<85.0
<75.0
<65.0
October-September (and previous 12 months)
>85.0
<85.0
<75.0
<65.0
 

Streamflows

Streamflow gages representing drought evaluation regions will be used to monitor streamflow responses to drought conditions.  Representative daily flow values will be compared with historic flow statistics for the period of record.  Representative daily streamflows above the 25th percentile for return flow frequency will be defined as normal conditions.  Representative daily streamflows between the 10th and 25th percentile for return flow frequencies will be defined as drought watch conditions.  Representative daily streamflows between the 5th and 10th percentile for return flow frequencies will be defined as drought warning conditions.  Representative daily streamflows below the 5th percentile for return flow frequencies will be defined as drought emergency conditions.  Gages selected to monitor drought severity in each evaluation region are listed below:

  • Big Sandy Drought Evaluation Region:  Clinch River at Cleveland, USGS Station 03524000
  • New River Drought Evaluation Region:  Reed Creek at Graham Forge, USGS Station 03167000
  • Roanoke River Drought Evaluation Region:  Goose Creek near Huddleston, USGS Station 02059500
  • Upper James Drought Evaluation Region:  Cowpasture River near Clifton Forge, USGS Station 02016000
  • Middle James Drought Evaluation Region: Appomattox River at Farmville, USGS Station 02039500
  • Shenandoah Drought Evaluation Region:  North Fork Shenandoah near Strasburg, USGS Station 01634000
  • Northern Virginia Drought Evaluation Region:  Accotink Creek near Annandale, USGS Station 01654000
  • Northern Piedmont Drought Evaluation Region:  Rapidan River near Culpeper, USGS Station 01667500
  • Chowan Drought Evaluation Region:  Meherrin River near Lawrenceville, USGS Station 02051500
  • Northern Coastal Plain Drought Evaluation Region:  Mattaponi River near Beulahville, USGS Station 01674500
  • York-James Drought Evaluation Region:  Chickahominy River near Providence Forge, USGS Station 02042500
  • Southeast Virginia Drought Evaluation Region:  No stream gages available to monitor.
  • Eastern Shore Drought Evaluation Region:  No stream gages available to monitor.

Ground Water Levels

Water table ground water monitoring wells representing drought evaluations regions will be used to monitor shallow ground water responses to drought conditions.  In areas west of Route 95, it was assumed that wells completed in shallow fractured rock formations are indicative of water table conditions.  Measured ground water levels will be compared with historic level statistics for the period of record. 

  • Measured ground water levels above the 25th percentile for all historic levels will be defined as normal conditions.
  • Measured ground water levels between the 10th and 25th percentiles for all historic levels will be defined as drought watch conditions
  • Measured ground water levels between the 5th and 10th percentiles for all historic levels will be defined as drought warning conditions
  • Measured ground water levels below the 5th percentile for all historic levels will be defined as drought emergency conditions
Monitoring wells selected to monitor drought severity in each evaluation region are listed below.  In drought evaluation regions where no appropriate monitoring wells exist, the ground water indicator will not be used.
  • Big Sandy Drought Evaluation Region:  No water table monitoring wells available to monitor.
  • New River Drought Evaluation Region:  Christiansburg Observation Well, USGS Local Number 27F 2 SOW 019
  • Roanoke River Drought Evaluation Region:  Roanoke-Nelson Observation Well, USGS Local Number 31G 1 SOW 008
  • Upper James Drought Evaluation Region:  Glasgow Observation Well, USGS Local Number 35K 1 SOW 063
  • Middle James Drought Evaluation Region: Buckingham Observation Well, USGS Local Number 41H 3
  • Shenandoah Drought Evaluation Region:  McGaheysville Observation Well, USGS Local Number 41Q 1; Blandy Farm Observation Well, USGS Local Number 46W 175
  • Northern Virginia Drought Evaluation Region:  Harper’s Ferry Observation Well, USGS Local Number 49Y 1 SOW 022; Arlington Cemetery Observation Well, USGS Local Number 54V 3
  • Northern Piedmont Drought Evaluation Region:  Gordonsville Observation Well, USGS Local Number 45P 1 SOW 030
  • Chowan Drought Evaluation Region:  Slade Farm Observation Well, USGS Local Number 57E 31 SOW 094C
  • Northern Coastal Plain Drought Evaluation Region:  George Washington Birthplace Observation Well, USGS Local Number 55P 9
  • York-James Drought Evaluation Region:  Toano Observation Well, USGS Local Number 56H 31 SOW 135B
  • Southeast Virginia Drought Evaluation Region:  Brinkley Observation Well, USGS Local Number 58B 13; Pungo Observation Well, USGS Local Number 62B 1 SOW 098A
  • Eastern Shore Drought Evaluation Region  P. C. Kellam Observation Well, USGS Local Number 63H 6 SOW 103A; Withams Observation Well, USGS Local Number 66M 19 SOW 110S

Reservoir Storage

Storage in major reservoirs will be used as a fourth drought indicator.  Major reservoirs in Virginia support a wide variety of uses that include water supply storage, electric power generation, and flow augmentation to protect water quality.  Water supply reservoirs will be evaluated based on eth estimated days of available usable storage.
  • Storage of greater than 120 days will represent normal conditions.
  • Storage of 90 to 120 days will represent drought watch conditions.
  • Storage of 60 to 90 days will represent drought warning conditions.
  • Storage of less than 60 days will represent drought emergency conditions.

Several large multi-purpose reservoirs will be evaluated as drought indicators, as listed below:

STATUS NORMAL DROUGHT WATCH DROUGHT WARNING DROUGHT EMERGENCY

Smith Mountain Lake

>793 feet msl

793 to 791.5 feet msl

791.5 to 790 feet msl

<790 feet msl

Lake Moomaw

>1565 Feet msl

1565 to 1562.5 feet msl

1562.5 to 1560 feet msl

<1560 feet msl

Lake Anna

>248 feet msl

248 to 246 feet msl

246 to 244 feet msl

<244 feet msl

Kerr Reservoir

<3 feet below the guide curve

3 to 6 feet below the guide curve

>6 feet below the guide curve

<288 feet msl

Reservoirs that will be used to monitor drought conditions are listed below.  In drought evaluation regions where no appropriate reservoirs exist, this indicator will not be used.

  • Big Sandy Drought Evaluation Region:  Big Cherry Water Supply Reservoir
  • New River Drought Evaluation Region:  No reservoirs will be monitored.
  • Roanoke River Drought Evaluation Region:  Smith Mountain Lake, Kerr Reservoir
  • Upper James Drought Evaluation Region:  Lake Moomaw
  • Middle James Drought Evaluation Region: Lake Moomaw, Charlottesville Water Supply Reservoir System
  • Shenandoah Drought Evaluation Region:  Switzer Water Supply Reservoir
  • Northern Virginia Drought Evaluation Region:  Occoquan Water Supply Reservoir, Lake Manassas Water Supply Reservoir
  • Northern Piedmont Drought Evaluation Region:  Lake Anna, Spotsylvania Water Supply Reservoir System
  • Chowan Drought Evaluation Region:  Emporia Water Supply Reservoir
  • Northern Coastal Plain Drought Evaluation Region:  Gloucester Water Supply Reservoir
  • York-James Drought Evaluation Region:  Newport News Water Supply Reservoir System
  • Southeast Virginia Drought Evaluation Region:  Kerr Reservoir, Portsmouth Water Supply Reservoir System
  • Eastern Shore Drought Evaluation Region:  No reservoirs will be monitored.
footer divider
footer divider
footer divider
Virginia Department of
Environmental Quality
629 East Main Street
P.O. Box 1105
Richmond, VA 23218
(804)698-4000

Advanced Search
Privacy Statement | Terms Of Use | WAI Compliance | Contact Us