Under the 50-year water supply plan, the South Fork Rivanna Reservoir (SFRR) will be allowed to silt in -- reducing its capacity by more than 80%.
Not only is the SFRR the largest and most important water supply facility in the area, it is also a highly valued recreational asset for the community.
Constructed in 1966, the South Fork Rivanna Reservoir (SFRR) is a water supply impoundment located on the South Fork Rivanna River three miles upstream from the confluence with the North Fork. This reservoir is the main source of drinking water for the RWSA Urban system. (The Urban Service Area consists of the city of Charlottesville, UVA, and the more densely populated parts of Albemarle County.)
Its large watershed of 260 square miles, provides a reliable source of stored water but also contributes to management challenges. A major issue is sedimentation. The SFRR had an original capacity of 1,700 MG (1.7 billion) but has lost an average of 1.1% of capacity a year due to siltation. Last measured in 2002 with a capacity of 1,100 MG and with no plan to manage for siltation, the reservoir is predicted to fall to 400 MG in the next 50 years.
In fact, the loss of the South Fork Rivanna Reservoir to siltation is written into the current water supply plan. In a memo to City Council on November 19, 2007, Tom Frederick states that "..about one-third of the new water storage proposed at Ragged Mountain is to replace storage expected to be lost at South Fork in the next 50 years,.."
Click here for a sedimentation chart for the South Fork Rivanna Reservoir from an RWSA water supply update, March 2004.
Since the watershed falls almost entirely within the County of Albemarle, prime responsibility for its care is in local hands. As of the early 1990s, the watershed was 73% forested (the best land use for water quality). However, steady development within the watershed is slowly depleting forest cover. Much of the watershed alteration that threatens water quality, such as increases in impervious surfaces like roads, driveways, and rooftops as well as non-protective landscape such as lawns, appears to have occurred along the tributaries closest to the reservoir.
Everything you always wanted to know about SFRR
South Fork Rivanna Reservoir and Watershed: Reflecting on 36 Years, Anticipating 50 years
by Stephen Bowler, Spring 2003