Written by John Boyle, Asheville Watchdog.
The City of Asheville has restored non-potable, heavily chlorinated water to about 95 percent of users, but its main source of water, North Fork Reservoir, remains stubbornly murky 26 days after Tropical Storm Helene.
At the Buncombe County daily storm briefing Monday, Asheville Water Resources Department spokesperson Clay Chandler shared a photo of a still very brown-looking North Fork Reservoir. The city treated the reservoir Wednesday and Thursday with minerals that were supposed to cause clay particles to sink, clearing the water near the surface.
That did not happen.
“And as you can see, the surface water has not cleared up very much at all, if any,” Chandler said. “What has happened — and which is almost completely opposite of what we expected to happen — is water at the deeper portions — 40 to 50 feet — have shown fairly significant improvement as far as clearing turbidity.”
Chandler said windy conditions on the two days of treatment last week roiled the surface waters, stirring up sediment. But water officials are not entirely sure why the lake remains so stubbornly brown, as it’s normally a “pristine” water source, and its feeder streams have cleared back up.
“There have been a lot of things that have happened in the last three and a half weeks that have defied logic,” Chandler said. “This is just the latest one. And again, we think that the windy conditions Wednesday and Thursday of last week, when that treatment was done, stirred up that surface water to the point that it was not going to clear up, treatment or not.”
Turbidity is measured in Nephelometric Turbidity Units, or NTUs, and the EPA requires filter water to be less than .30 NTU for consumption. At North Fork, normal filtered water is between .03 and .05 NTU, meaning it’s “typically exponentially cleaner than required,” Chandler said previously.
The raw water typically entering the lake has an NTU of 1 or less, but Monday turbidity readings at North Fork were hovering between 25 and 27, Chandler said. On Oct. 11, the water registered 30 NTU.
The city water system still has a system-wide boil water notice in place. The water is safe for showers, laundry and flushing commodes, but it is not safe to consume unless boiled, and even then, the city still recommends using bottled water for consumption.
Chandler said Monday that he still had no timeline on full restoration of water, “or at least an accurate one that we can provide as far as when that lake will clear up and we can treat the water and push it through our filters and all of that.”
“But we are certainly hopeful that the second round of treatment will sort of push the ball down the court as far as that reservoir clearing up,” Chandler said.
The city treated the water with a mix of aluminum sulfate and caustic soda. Workers have used a boat to dump tote bags full of chemicals into the reservoir in an effort to purify the water.
Aluminum sulfate is a “salt-ish” mineral the department uses to regularly treat the reservoir, as it makes clay particles coagulate and sink, leading to clearer water for filtering and treatment. Caustic soda helps with optimum pH levels for the coagulation to work best.
The city is awaiting arrival Thursday or Friday of a “curtain” system that can be installed at the reservoir to help with turbidity. The city will have to install and anchor the curtains in place.
Once in, they’ll create a 500-foot circle around the intake.
“And we are pretty confident that by a week from today, we will be doing a second round of that in-lake treatment process,” Chandler said.
The reservoir has intakes for water treatment at 21, 50 and 80 feet. North Fork serves 80 percent of Asheville’s 63,000 water customers.
Asked if the city has considered bringing in or installing heavier-duty filtration equipment designed for turbid water, Chandler said the technology does exist, but there are challenges.
“The problem that we’re going to run into at North Fork is that North Fork, on average, pushes 25 million gallons a day into our system, and mobile or portable treatment facilities are just unable to handle that volume,” he said.
Chandler said that over the weekend, the city reached 95 percent of system restoration with non-potable water. People in the Eastmoor and Bee Tree areas in east Asheville got water back.
But some areas remain without any water, including Town Mountain and Webb Cove Road, that “have proven to be particularly problematic,” Chandler said, noting that includes 65 to 70 homes.
“A three-inch line that serves that area got washed out by a landslide after the storm, and so we’ve had to do a little bit of coordinating with NCDOT as far as road repair before we can restore service there,” Chandler said. “Our contractors are going to work on a temporary solution that we hope will be in place Wednesday or Thursday. That should restore service to most of the Town Mountain, Webb Cove areas that currently do not have water.”
Asheville Watchdog is a nonprofit news team producing stories that matter to Asheville and Buncombe County. John Boyle has been covering Asheville and surrounding communities since the 20th century. You can reach him at (828) 337-0941, or via email at [email protected]. To show your support for this vital public service go to avlwatchdog.org/support-our-publication/.