South Slave’s lakewater quality has changed significantly over the last decades and low water levels are just one of multiple factors, says GNWT’s Chief Environmental Health Officer Dr. Chirag Rohit.
Dr. Rohit says lakewater quality, which has changed significantly since the Hay River treatment plant was built, is the cause of high levels of trihalomethanes behind the water advisories issued Monday for Hay River, Enterprise, Kátł’odeeche First Nation and Ka’a’gee Tu First Nation.
The chief officer told North Now the heightened levels were first detected in September, but because of the way Health Canada assesses water samples for trihalomethanes, those results had to be assessed, remeasured and confirmed before being made public.
According to officials with GNWT’s Environmental Health Office and Canada Health guidelines, cancer risks are related to long-term exposure of 70 years or more. Those risks are increased to some degree by pre-existing health conditions like COPD and asthma, said Dr. Rohit who is recommending all members of the public take precautions as outlined by the advisory issued earlier this week.
The Chief Environmental Health Officer explained that the heightened levels of trihalomethanes are caused by the reaction of chlorine with naturally occurring organic material which has accumulated substantially in the lakewater in the decades since the water treatment plant was built.
“What we know for certain is that the source water, the water that we are taking in from the lake, over the years, has seen higher amounts of organic material. And that organic material is interacting with the chlorine used for disinfecting. And that’s where we end up having THMs”
Investigations have found that climate change and low water levels are part of the picture, but “multiple” factors are involved, said Rohit.
The THMs are produced when the chemical chlorine is added to the lakewater.
“To have a higher level of chemicals called trihalomethanes whih are biproducts of when the drinking water is disinfected with chlorine, THMs are a group of chemicals, they are produced where the chlorine interacts with organic materials in the water,” explained the chief environmental officer.
“The way THMs are monitored in Canada and because this is a standard set by Healthcare Canada. Is that it’s one sample taken every three months. And then over one year, four samples are collected and those values are averaged out,” added Dr. Rohit.
Over the years, the values of THM’s have been “fluctuating” in the South Slave’s lakewater but “slowly creeping up,” said the chief environmental officer.
“So for the town of Hay River water treatment plant, in September, we identified that over the last one year. Trihalomethanes were creeping up and the average was now higher than the Health Canada guideline set for the drinking water in Canada.”
Dr. Rohit said that the test result average for the month of September showed levels of THMs that for the first time were higher than Health Canada guidelines.
“We ended up issuing a precautionary public health advisory. The main reason we want to issue this advisory is so that the public is aware of what’s happening with the drinking water, as well as give them a very clear. Guidance and information about what action they can do to reduce the risk of exposure from THMs,” added Dr. Rohit.
The Environmental Health Unit is working with the affected South Slave communities to monitor water quality and to reduce levels of the trihalomethanes, said Dr. Rohit.
“Throughout the period, we work with every single water treatment plant, and the community governments to monitor the drinking water quality,” he said.
“We’ve been working with the towns to provide some time to monitor the THM values as well as exploring methods and optimizations, the possibilities that can be implemented to reduce the THMs levels, but part of the other thing that we do is notify public when the measures are higher. And so, the action can be taken at the individual level to protect themselves and their loved ones,” added Dr. Rohit.
The chief environmental officer said that according to assessments done so far, there’s no damage or technical issues with the Hay River water plant. But because its infrastructure is outdated, the system is not able to filter the amount of organic materials that come in and when chlorine is added, THMs are produced.
The chief environmental health officer said that currently, the testing is being done monthly in place of the standard quarterly sampling to help officials and engineers understand how the modifications at the treatment plant impact the THM levels.
“At this point, we are monitoring those samples as they are being collected and analysed against the Health Canada values for the human health risk.”
Dr. Rohit said that there is no time estimate as to when the high THM’s will be reduced and the water advisory removed.
“The treatment system is being optimized as we speak right now, certain changes in technical modification are being made to the treatment system. And those water treatment plants are complex systems. They have a large system so it takes a little bit longer, but we are expected to collect new samples next week.”
The chief environmental officer is advising residents to take precautions before drinking water or using water for food preparation and says anyone with questions is welcome to reach out to the environmental health unit.
A public information session and public questions and answer period will be held today at 7 p.m. MT at Hay River’s town hall and livestreamed via the town’s Youtube channel today
North Now has reached out to leadership in Hay River, Enterprise, Kátł’odeeche First Nation and Ka’a’gee Tu First Nation for more information and will share their responses when available.
