Butte residents will receive a letter in their next water bill with a warning that infants, the elderly and people with weak immune systems may not want to drink the city’s tap water.
The notice is required by state officials because Butte-Silver Bow recently had to resume using water from Basin Creek. The state’s filtration waiver on the creek expired in February but the county needs it in summer to supply enough water during peak demand.
Shelley Nolan, manager of public water supply with the state Department of Environmental Quality, said the unfiltered Basin Creek water is at risk to have cryptosporidium. She said the state does not want to alarm people, but the microscopic parasite is not killed by chlorine and could pose a risk to certain people.
“We want people to be wary of their own health and take precautions,” Nolan said. “Individuals that don’t have a good immune system can’t rid their bodies of cryptosporidium.”
But Rick Larson, county utilities manager, said they are not putting water into the system that is hazardous to health. He noted the same letter was sent last year and said the water is rigorously tested to ensure it’s safe.
“We test for cryptosporidium and we don’t find it,” he said. “We monitor very, very closely the crypto, we monitor very, very closely the algae blooms and take care of those with chemicals.”
However, Nolan said as a precaution for water that could contain the parasite, pregnant women, young children, the elderly and people with a weakened immune system should boil the tap water for a minute before drinking it. Water to be used for infant formula should also be boiled.
Cryptosporidium can cause nausea, cramps and severe diarrhea as the body works to get rid of the parasite. Nolan said healthy people can get rid of it but it’s more difficult for those people at risk.
The notification letter is required by the DEQ because Butte is out of compliance with federal rules covering the treatment of surface water.
Cryptosporidium is microscopic, but is removed by filtration. But the Basin Creek water is not filtered. For years it didn’t have to be because the water was so clean and the state granted it a waiver.
In recent years the deterioration of the watershed, largely because of pine beetle infestation, has caused the state to revoke the waiver from filtering the water.
Larson said the bigger problem they have is with the haloacetic acids that are produced when the organic carbons are mixed with chlorine. But he said it takes years of exposure to pose a risk.
“This is not an acute problem; it’s a chronic one,” he said. “We only use this water in the summer and we don’t see it as a big problem.”
In the long run, Larson said they are working to either quit using Basin Creek water or filter it.
The county last year contracted with an engineering company to draft a water master plan. It presented two options to upgrade Butte’s water system, including a new filtration plant either at Basin Creek or for water from Silver Lake west of Anaconda.
Larson has requested $90 million in grants from the state Natural Resource Damage Program to help pay for the overhaul of the water system. But that won’t be decided until the end of the year, and even with the grants construction of the water infrastructure won’t start until next year.
He said while the water has consistently tested negative for cryptosporidium, he’s working to make changes as quickly as possible so Basin Creek water isn’t needed. The plan calls for adding an upgrade to the Big Hole treatment plant and main transmission line so it can filter more water by next summer.
“I fully intend to not use Basin Creek next summer if I can,” he said.