By Ann McCreary
Both Twisp and Winthrop are disinfecting their municipal water supplies after receiving test results that show positive for “total coliform.”
Twisp Public Works Superintendent Howard Moss added chlorine to reservoirs on Saturday (Sept. 28), and Winthrop planned to add chlorine to its reservoirs Wednesday (Oct. 2).
Public works officials said the presence of coliform in the town water sample is not cause for alarm and doesn’t pose health risks or require boiling water.
“Coliform bacteria in itself is not harmful,” Moss said. “It’s an indicator bacteria. If you find total coliform in water there could be other bacteria present that could be harmful.”
Total coliform is a large collection of different kinds of bacteria that are common in the environment, according to information from the Washington Department of Health (DOH), which requires municipalities to regularly test for water quality. It is easy and inexpensive to test for coliform bacteria, according to DOH.
“Coliform bacteria are unlikely to cause illness. However, their presence in drinking water indicates that disease-causing organisms could be in the water system,” according to DOH.
Moss planned to take new water samples this week, and again next Monday (Oct. 7) after the chlorine has completely left the system. He said results from the testing will probably be available next Wednesday (Oct. 9).
Rick Karro, Winthrop public works superintendent, said chlorination of the town’s three water reservoirs will continue for up to a week. “I imagine it will be detectable for a week to two weeks.” Further testing will be conducted next week, he said.
In a letter to Twisp residents last Thursday, Moss explained plans to add chlorine to the town’s three water reservoirs, and predicted that the taste would be affected for a few days.
“I’m not getting a lot of feedback from customers” regarding chlorine taste, he said Monday after the reservoirs had been treated. He said the chlorine would remain in the reservoirs for about 24 hours, and then public works crews would flush the chlorine by opening fire hydrants to bring fresh water into the system.
Winthrop public works officials said they planned to personally contact Lost River Winery and the Old Schoolhouse Brewery to let them know that municipal water used in their beverage production might have an altered taste.
Test results a problem
The disinfection was necessary because both towns have been working to address unsatisfactory water test results received in August and September. The towns flushed their systems, but each received another test result that was positive for total coliform.
Last month DOH required additional samples from both towns, rather than the usual one or two. When both towns had another sample that was positive for total coliform, “DOH instructed us that we either flush or chlorinate the system within 30 days,” Moss said. DOH also required the towns to notify water customers of the unsatisfactory results.
“The samples that showed the presence of coliform were further tested to see if other bacteria of greater concern, such as fecal coliform or E. coli were present. None of these bacteria were found,” residents of Twisp and Winthrop were told in letters informing them of the test results.
The letters advised that boiling water was not necessary, but that people with “severely compromised immune systems, infants and some elderly may be at increased risk and may want to contact their health care provider for additional guidance.”
Moss said he has heard no reports of sickness related to the water problems.
As recommended by DOH, Twisp flushed its entire water system between Sept. 18 and Sept. 25. “We ran six fire hydrants for 20 minutes at 1,000 gallons per minute,” and then took three more samples, Moss said.
Following flushing, one of three water samples was still positive for coliform bacteria, prompting the town to take the step of disinfecting the water reservoirs.
Moss said the town’s three reservoirs hold a total of 725,000 gallons of water, and Moss added about 12 gallons of chlorine. He said the concentration of chlorine was “quite a bit less than half the amount we would maintain in a swimming pool.” Moss said he expected any chlorine taste to be gone by Thursday.
Winthrop’s reservoirs hold about 750,000 gallons of water, Karro said.
Source unknown
The source of the coliform isn’t known, said both Twisp and Winthrop public works officials.
“One theory is that because of the relatively hot, late summer, and three reservoirs exposed to the heat … it could potentially make the problem develop,” Moss said.
Karro noted that Winthrop had two water main breaks just before the water sampling that came back positive, and “the disturbance to the system … might have stirred up minor sediment in the pipes resulting in the positive test result.”
He said customers blowing out their irrigation lines for winter and stale water in dead end or little used lines might also be a cause.
If disinfecting and flushing the water system doesn’t resolve the problem, Moss said, another effort to disinfect with chlorine will be made, with higher levels of chlorine.
If the problem still persists, Twisp could face a bigger problem, Moss said. “If we still have coliform, that indicates the problem is in the well itself – the source.”
At this time of year, Twisp’s water comes from a well on Lincoln Street, behind Town Hall. If necessary, chlorine will be added to the well, Moss said.
