Graphic courtesy of WVWA
The Western Virginia Water Authority (WVWA) is clarifying the condition of the Carvins Cove Reservoir and the potential water demand from the proposed Google data center in Botetourt County as voluntary water conservation measures remain in effect across the region.
In an Aug. 21 response to questions about the region’s water supply, the authority said an apparent sharp decline in the reservoir’s reported water level earlier this month was caused by a damaged monitoring sensor, not an actual loss of nearly 2 billion gallons of water.
The sensor that automatically records the reservoir’s water level was damaged during a storm and defaulted to the bottom of the published scale. The authority said the inaccurate graph was removed after it was discovered and replaced with information about the sensor problem, while accurate manual readings continued to be published.
At the time of its response, WVWA reported Carvins Cove was 17.9 feet below the spillway. The region remains under Stage 1 voluntary water conservation measures, with mandatory conservation not expected until later this fall under current water-use conditions.
According to the authority, Carvins Cove reached levels of approximately 25 to 30 feet below full pond during late August in the 1999 and 2002 droughts. Spring Hollow Reservoir was 17.5 feet below full pond, or 78.3% of its capacity.
To reduce reliance on Carvins Cove, WVWA said it is increasing water from Spring Hollow, using wells, purchasing some water from Salem and repairing system leaks.
The authority’s website lists Carvins Cove’s full-pond design capacity at 6.42 billion gallons.
Questions have also been raised about whether that figure includes water that cannot be accessed for normal water-supply operations.
WVWA said the 6.42-billion-gallon figure is the reservoir’s design capacity. Multiple intake pipes are positioned at different elevations at the dam, allowing operators to draw water from different levels as reservoir conditions change, according to the authority. The lowest intake is at an elevation of 1,120 feet, while additional infrastructure below that level can be used to flush sediment. Temporary pumping systems could also be deployed to capture remaining water if necessary.
The authority’s bathymetric studies—the measurement of water depth and the shape of the bottom surface—indicate some sedimentation has occurred over the reservoir’s approximately 80-year history and estimate a loss of about 4% to 5% of storage capacity, concentrated below the lowest intake. WVWA said sedimentation has not had a significant effect on the reservoir’s overall storage capacity.
An engineering curve showing the relationship between reservoir elevation and storage capacity is available, according to WVWA. Its website also provides current reservoir levels, gallons remaining, percentage of capacity and historical measurements.
The proposed Google data center has become a particular focus of water-supply questions because the company’s potential demand could increase as the project expands.
At a recent Amsterdam District town hall, Google representatives said the company’s current agreement with WVWA provides for up to 2 million gallons of water per day for its initial operation. The authority confirmed that figure.
If Google seeks additional water as the project expands, the agreement allows the company to request up to another 6 million gallons per day, for a potential total of 8 million gallons per day, according to WVWA. Any additional allocation would require a request to the WVWA Board of Directors.
The 8-million-gallon figure therefore represents a potential maximum allocation rather than Google’s current water allocation.
The first data center building will use air cooling instead of water cooling, according to WVWA. As a result, water for that building will primarily be used for restrooms, sinks and fire protection rather than cooling computer equipment.
WVWA said Google has not announced the cooling systems planned for the second and third buildings. The authority said the project’s total water demand is expected to be lower than originally anticipated because the first building will not use water for cooling.
The authority also noted that maximum-day demand figures are used for peak system planning and that average daily demand is expected to be lower because cooling requirements vary seasonally.
WVWA’s existing Drought Contingency Plan was developed in 2007, before the possibility of a large data center customer in the region was anticipated. The authority plans to update the plan in the future to account for very large water users, but said it will not make changes while the region is experiencing a drought.
Google has agreed to follow the authority’s existing drought requirements, according to WVWA.
The authority reviewed Google’s request for up to 2 million gallons per day for the project’s first phase before the Water Authority’s Board of Directors approved the request.
The county said future water demand will be considered through broader regional water-resource planning. According to the county, WVWA’s drought planning and consideration of future water users will be part of that process, while the Roanoke Valley-Alleghany Regional Commission is undertaking an updated regional water plan.
A representative from the Regional Commission was expected to update the Board of Supervisors on regional water planning at its Tuesday meeting, according to the county.
The county said those planning efforts will consider future water demand, system capacity, drought conditions and other factors as the region plans for the coming decades. As the Google project moves through future phases, its water needs will be considered as part of that broader planning and regulatory process.
WVWA also pointed to changes in regional water use and infrastructure since the 2002 drought. The authority said it treated approximately 23 million gallons of water per day for about 55,500 customers 20 years ago. Today, it treats approximately 21 million gallons per day for about 70,000 customers, which WVWA attributed to increased efficiency.
The regional system also has additional water sources and improved connections between them, according to the authority. Crystal Spring and Muse Spring are now contributing to the system, while a project completed two years ago allows treated water from the Spring Hollow distribution area to flow into the Carvins Cove distribution area.
The authority said it has not received a request from a new customer for up to 1 million gallons per day, disputing a recently circulated claim that such an agreement had been reached.
WVWA remains in the voluntary conservation phase of its drought plan and is closely monitoring reservoir levels. The threshold for mandatory conservation varies during the year and, based on current water use, is expected to be reached at about 26 feet below full pond later in the fall, according to the authority.
The authority’s current reservoir information and drought updates are available at https://www.westernvawater.org/level.
~ Fincastle Herald staff report
