Asheville’s backup water filtration system has ended. Now what?

ASHEVILLE – The temporary pretreatment systems at two of the city’s water reservoirs, which served as backups after Tropical Storm Helene, are now offline.

They are being dismantled and removed, a process that will likely be finished by the end of the month, Water Resources Department spokesperson Clay Chandler said Dec. 4.

The temporary systems were installed after Helene wreaked havoc on the city’s watershed in late September 2024, leaving it more vulnerable to future storms. If the turbidity at the typically pristine reservoirs were to again spike, they would have ensured water could continue to be filtered — rather than pumping non-potable, highly chlorinated water out to a majority of Asheville’s 160,000 customers.

But the system was costly. It operated at both the North Fork and William DeBruhl water treatment plants, which sit east of Asheville near Black Mountain and Swannanoa, and cost about $6 million a month. It was paid for by funding from the Federal Emergency Management Agency. The city did not shoulder any of the cost.

The city announced in October that the systems would only stay in place through Nov. 30.

“That layer of redundancy is gone,” Chandler said in a December call with the Citizen Times. He said the city was grateful to keep it online through hurricane season, which ended in November. In the system’s nearly year of operation, the city did not experience a storm that required it to fall back on the temporary units for full water production.

“Those systems were ready to go if we needed them to be. But no, we never reached the point to where we had to shut down our existing processes and rely completely on the temporary systems,” Chandler said.

While the watershed is still more vulnerable than it was before Helene, Chandler said debris removal at North Fork’s Burnett reservoir — which serves 80% of the system — is more than halfway done. This is helping to strengthen the watershed and reduce future vulnerability.

Chandler said it is in a much stronger position than it was even six months ago. If a large weather event were to increase turbidity, meaning the cloudiness caused by sediment and debris, the city might have to consider feeding non-potable water into the system, but the likelihood of that happening is much less than it was.

“I don’t think people have reason to worry. Our system is as strong as it was before Helene, we think. The watershed will eventually be as strong as it was before Helene,” Chandler said. “It’s not going take years for that happen. We think it will be in a very, very good position once debris removal wraps up in the next couple of months.”

Turbidity fell back to pre-Helene levels in early spring and “it’s been business as usual for us for several months now.”

Other than day-to-day operations, the department’s No. 1 priority is resiliency.

It is working toward eventual installation of a permanent solution — a $150 million to $200 million project with a buildout that could take up to five years, once funding is secured. It is among the eight projects the city applied for Hazard Mitigation Grant Program dollars to fund.

There are several other ongoing water recovery projects. Learn more at https://publicinput.com/k06762.

What was the temporary water pretreatment system?

The systems were originally installed by the U.S. Army Corps of Engineers, though operations were eventually taken over by private contractors.

It used dissolved air flotation devices, or DAF units, to remove sediment from the water. It installed 13 of these units at North Fork and three at DeBruhl. They look similar to shipping containers, Chandler said.

As for why the process is so pricey, Chandler said it was sophisticated equipment that required a lot of personnel to operate and had substantial energy costs. The operation at North Fork was a “unique,” custom-build, possibly one of the largest of its kind constructed in the country.

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Sarah Honosky is the city government reporter for the Asheville Citizen Times, part of the USA TODAY Network. News Tips? Email shonosky@citizentimes.com or message on Twitter at @slhonosky.