DENVER—High concentrations of chlorine being used to purge salmonella bacteria from Alamosa’s water system were expected to drop far enough Saturday that residents could use the water for showering.
The disinfection process began Tuesday, five days after officials confirmed the presence of salmonella in the water. The source is still unknown.
Nearly 300 people have become ill, with 73 cases of salmonella confirmed.
During the cleansing, the chlorine level in Alamosa’s tap water is more than five times greater than what’s needed to keep a swimming pool clean. Authorities say it could be April 7 before levels are low enough in the 50-mile network of pipes that residents can drink the water.
In the meantime, volunteers and the National Guard are passing out clean water at distribution points, and officials say that tap water is usable only for flushing toilets.
Not everybody has listened to the warnings. Gary Wuckert said he’s been showering with the water.
“I figured if I get irritated it’s my own fault,” he said in a telephone interview. “I may be cleaner than I have been in 30 years.”
Salmonella can cause diarrhea, fever and stomach pain. Victims typically recover on their own, but the elderly, infants and people with impaired immune systems may require treatment.
Salmonella bacteria are usually food-borne, and contamination of public water systems is rare.
Officials have identified the strain of salmonella in the water system as one commonly found in the feces of birds, deer and other warm-blooded animals around the southern Colorado agricultural community of 8,500.
How it got there remains a mystery.
Steve Gunderson, director of the state health department’s water quality division, said construction of a $16 million water treatment plant has been ruled out as the cause.
“(The plant is ) coming online this summer, but it’s not to where they tapped into the water system,” said Gunderson, whose agency regulates water systems in the state and is helping the city trace the source of contamination.
Testing on the new plant, built to remove arsenic slightly above the federal standard, was to begin in June.
The city hasn’t had a water failure since January and maintenance on the system hasn’t taken place since fall, Gunderson said.
Routine samples sent to the state on March 5 showed no bacteria contamination, while those taken about two weeks later were contaminated.
City manager Nathan Cherpeski said the contamination could have come from a crack in a pipeline or from a water-storage site.
Cherpeski said none of the potential sources investigated so far have panned out.
“As we get evidence, it will start to appear we have the source, but at the end of the day we start to have evidence it’s something else,” he said.
Even if officials can’t identify the source of contamination, residual chlorine in the tap water should be enough to keep it safe to drink, Cherpeski and Gunderson said.
Alamosa’s water is drawn from a deep well and had been the largest of some 100 water systems in the state that didn’t require chlorination. City plans called for the new water plant to include chlorination even before the salmonella outbreak.
