Residents of about 80 homes in East Sooke in Mount Matheson Estate have been advised to boil their water, a precaution against parasites, bacteria or viruses.
Water officials with the Capital Regional District and public health doctors with Island Health first issued the boil-water advisory on July 28 to residents served by what is known as the Wilderness Mountain Water System.
It was a response to test results conducted on source water revealing a sudden increase in the coliform count indicating fecal contamination and the possibility of gut parasites such as giardia, cryptosporidium, or harmful bacteria and even some viruses.
Dr. Murray Fyfe, medical health officer with Island Health, said no specific pathogens have been found. But the presence of the coliforms calls for precaution.
The homes are all served by a small water utility that relies for its source on a human-built lake, little more than a pond, known as Wilfred Reservoir. Rain fills it during the winter and the water utility draws it down during the summer.
It was built by a developer to serve homes constructed on large, two-to-three acre lots. After construction the developer sold the utility to another operator. Several years ago residents petitioned successfully for the CRD to take it over.
Christoph Moch, CRD manager of water quality operations, said the reservoir is now being tested twice a week. When tests reveal the water quality is well on the rebound, the advisory will be lifted.
Moch said a few years ago the CRD installed a small purification system and chlorination plant on the reservoir. But filtration was ruled out as too expensive for a such a small utility.
He said the latest water tests have showed the source water to be too turbid, that is too cloudy with suspended material, to allow the public to drink it.
He also said the current conditions are something new for observers of the reservoir. It’s likely the result of multiple factors, summer heat being just one.
“Warm water is certainly a very fertile growing ground for any bacteria or all life,” said Moch.
“Unfortunately, there are other processes at work that we haven’t seen before.”
“We’ll have to wrap our heads around and do some studies,” he said.
“These man-made, little lakes are a little more difficult to manage and keep on a stable ecosystem than naturally developed lakes.”