Residents in Mesachie Lake are once again able to enjoy their historically pristine drinking water after a brief and highly atypical boil water advisory issued for the community last week.
On Aug. 10, Cowichan Valley Regional District officials issued the advisory after receiving water sample results from Mesachie Lake with an E. coli count of three.
“You’re not allowed to have any E. coli sample in any sample ever, and so the immediate effect of that is a boil water advisory,” said Brian Dennison, manager of water management at the CVRD. “That around here is a top priority issue.”
The sample in question had been taken as part of the district’s regular weekly bacteriological test conducted on all 19 CVRD water systems. Every Monday or Tuesday samples are taken from each water system, and from a different site each time — any given town or community has high flow areas and low flow areas — in order to ensure a representative sample.
Dennison said the groundwater used by residents in Mesachie Lake has been clean for “ages and ages and ages,” which is why his staff was surprised by the E. coli results from Island Health, where the CVRD sends its water samples.
According to Dennison, new water systems are required to chlorinate their water, however, because Mesachie Lake uses an older system that hasn’t had any problems, no one is requiring the community’s water to be chlorinated regularly.
“It’s one of very few systems you’ll find that has that status,” he said.
When the CVRD was notified of the E. coli count, it immediately issued the boil water advisory and staff went door-to-door to notify residents of the potential problem. A second water sample was taken and then the reservoir’s water was chlorinated and retested. By Saturday all those results came back clean.
Todd Etherington, the CVRD’s utilities operations superintendent, said these re-sampling results did not come as a surprise to him.
“We’re 99.9 per cent sure it has nothing to do with the water system itself and that it was either a clinical or a sampling error,” he said, suggesting one possible cause for an inaccurate E. coli reading was sampling equipment not properly disinfected after coming in contact with the ground or other places that could cause bacterial contamination.
Another possibility is that a piece of lab equipment, where the samples are tested, might not have been cleaned properly.
“Mesachie Lake has had 40 years of perfect water quality, so why all of a sudden? That’s why it leads us to believe it was definitely either sampling or lab error,” said Etherington. “If there was bacteriological E. coli present Monday it would have still been there Wednesday, but it wasn’t.”
Etherington said for the most part, households he and his staff visited in Mesachie Lake and the people they spoke to were understanding about the situation. He said some people were a bit angry that they had been drinking potentially contaminated water between when the first samples were taken on Monday and when the advisory was issued on Wednesday, but Etherington said there’s really nothing the CVRD can do to prevent that.
“It’s just like getting blood work done, you don’t know the results right away. There’s a lab process that has to take place… It’s the same in any water system anywhere around the world. You don’t know right away.”
However, by and large the community’s response was “fantastic.”
“The folks in Mesachie Lake were great, they knew it was just protocol we were following,” he said.