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Reservoir Levels and Drought Advisories

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The Department of Environmental Quality issued a Drought Watch on Wednesday, October 11, 2017? 

What is a Drought Watch Advisory?

According to DEQ, A Drought Watch Advisory is intended to increase awareness of conditions that are likely to precede a significant drought event and to facilitate preparation for a drought.  An advisory was issued on October 11, 2017 for the Upper Roanoke River basin because drought watch indicators in the state’s Drought Assessment and Response Plan have been met.

According to the Virginia Drought Monitoring Task Force, an interagency group representing state and federal agencies, the primary factors contributing to the declaration of the drought advisory are:

  • Precipitation totals are less than 75% of normal over the past 90 days and less than 25% of normal over the last 30 days across much of the areas covered by the Middle James, Roanoke River and Shenandoah regions
  • Stream flows are lower than 75 percent to 95 percent of recorded flows, indicating a moderate to severe hydrologic drought – a period of below-average water content in streams, aquifers, lakes and soils.
  • Groundwater levels are lower than 75 to 95 percent of previously recorded September and October levels.

 

How does this impact the Western Virginia Water Authority's customers?

The Authority's drinking water supply comes from a variety of surface water and groundwater sources.  While the Drought Watch Advisory is triggered by precipitation and river/stream flows, the Authority's two largest sources of water in the Roanoke Valley, the Carvins Cove and Spring Hollow Reservoirs, offer the benefit of storing water for future use. Instead of having to rely on one source of water or a river that is immediately impacted by drought conditions, the Authority can balance the drinking water needs of customers across five surface water sources of water, a large groundwater source and multiple wells.

The Carvins Cove Reservoir holds 6.42- billion gallons of water and  the Spring Hollow Reservoir holds 3.2-billion gallons of water at full pond. Based on current demand, these reservoirs store two-years worth of water.

Although Authority customers are encouraged to always use water wisely, the available water supply in these reservoirs and the Authority's other sources does not suggest that any conservation measures are not needed to be put in place at this time.

What are the current reservoir levels?

The reservoir levels of Carvins Cove and Spring Hollow are monitored daily and updated each morning on our online reservoir level page.  While the reservoirs are not currently full, each reservoir still holds over 85% of their full-pond capacity.

These levels are compared to historic levels at the same time of year.  The Authority expects the reservoirs to be at their lowest level during the fall because of summer evaporation, a historically dry time of year and increased demand for water during the summer months.  In late fall, remnants of tropical storms and late season rain events typically start to fill the reservoirs again.

 Is there a Drought Plan at the Western Virginia Water Authority?

Because Carvins Cove depends on participation and runoff from the watershed to replenish its supply, the Western Virginia Water Authority's Drought Contingency Plan is based on the Carvins Cove reservoir levels during a particular month of the year.  Extensive precipitation and reservoir level data gathered over the decades was used to develop this plan.   Declining reservoir levels trigger specific water use restrictions.    Based on current levels, the level of Carvins Cove would need to drop almost 15-feet in order for Voluntary Water Conservation, the first step of the plan, to be triggered.

If you have additional questions about your drinking water or the water supply, please contact our Customer Service team at 853.5700 or info@westernvawater.org.