RWSA briefed on reservoir-connecting waterline, reservoir health

(This article was initially published as part of the May 11, 2021 edition of Charlottesville Community Engagement)

One of the largest capital expenses facing any governmental entity in the community is the nine and a half mile waterline the Rivanna Water and Sewer Authority (RWSA) has planned. Long planned, the line will connect the South Fork Rivanna Reservoir and the Ragged Mountain Reservoir. Ragged Mountain is currently fed by a pipeline from Sugar Hollow Reservoir, one that is nearing a hundred years old. The new waterline won’t be built for several more years, but the RWSA has been acquiring the right of way for the project. Executive Director Bill Mawyer gave his Board an update on April 27, 2021.

“The Albemarle County School Board granted about a one mile easement for the Rivanna to Ragged Mountain project this month,” Mawyer said. 

In all, the RWSA has easements for about six of the 9.5 miles and is in negotiations with the University of Foundation and private property owners for the rest. The RWSA has a 40 year lease with the city of Charlottesville to operate the Ragged Mountain reservoir which expires in 2052. There’s talk already of extending those terms given the community investment in the water supply plan.

“So as an example based on our current schedule, we would finish the new pipeline say around 2033, and then in effect we would only have 20 years left on the lease of a major water supply facility that we’ve just spent a lot of money on to expand and build the pipeline so we can fill it,” Mawyer said. 

Easement map for the alignment of the South Fork to Rivanna Reservoir waterline

The RWSA Board also got an update on the health of the five reservoirs maintained by the authority.  Their usable storage volume is updated every ten years according to water resources manager Andrea Bowles.

“We get this information from our bathymetries that we do,” Bowles said. “We do bathymetries for the urban system reservoirs every ten years.”

One of the concerns is the presence of algae in reservoirs, which can lead to oxygen depletion that threatens aquatic life. Each of the five reservoirs has a slightly different balance and Bowles explained how algae is managed. Beaver Creek Reservoir is currently the one most prone to blooms. There were five at the Crozet waterway in 2020, but none of them were problematic enough to require treatment. 

“That is the reservoir that we’re going to do an alternative of hypolimnetic oxygenation to try to help with blooms,” Bowles said. 

An algae bloom at Ragged Mountain Reservoir is underway and treatment was expected to begin last week. 

“We are having an issue with an algae called dinobryon which is a golden algae, not a blue-green algae, it doesn’t produce the toxins,” Bowles said. “We have that right now going on in Ragged Mountain. It is a big taste and odor producer and we have a threshold and it is slightly over the threshold.” 

The RWSA next meets on May 25. 

A snapshot of the usable storage volumes for the five RWSA reservoirs

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