This blog was updated on July 5, 2021

The West Credit River is home to a one of the last remaining self-sustaining native Brook Trout populations in southern Ontario. But they are under threat from a proposed Wastewater Treatment Plant that will dump its effluent into the river.

Brook Trout is a sentinel species that requires a pristine coldwater ecosystem, but the sewage effluent discharge will cause thermal pollution, and warm the river, placing this sensitive species at great risk. Even ‘best technologies’ can be insufficient when treated sewage effluent is released into a sensitive aquatic ecosystem such as the West Credit River.

West Credit River
A young Brook Trout in the West Credit River. Photo by Steve Noakes.

This issue is important because:

  • Brook Trout are the canary in the coal mine.
  • Every day, the proposed Erin Wastewater Treatment Plant will dump 7.2 million litres of sewage-effluent daily into the West Credit River – a relatively small receiving stream.
  • Stream temperature is crucial given its influence on oxygen depletion, ammonia toxicity, and Brook Trout survival.
  • Town of Erin Council’s sewage effluent will place Brook Trout at imminent risk of demise.
  • Urban development is a primary reason why Brook Trout populations in southern Ontario have declined by over 80 per cent over the last 70 years.
  • The Environmental Study Report stated that “Brook Trout redds (fish nest and spawning) were extremely abundant in the study reach and the area provides habitat for this critical life stage.”
  • Warm sewage effluent discharged into the West Credit River could destroy important Brook Trout spawning, nursery and rearing habitat.
  • The town of Erin, the Ministry of Natural Resources and Forestry, the Ministry of Environment Conservation and Parks and the Credit Valley Conservation Authority all agreed that “the most productive Brook Trout spawning reaches and the best Brook Trout populations in the West Credit River are located downstream of Erin Village and the longest contiguous Brook Trout habitat in the Credit River watershed is the West Credit River between Erin and Belfountain.”
An abundance of redds (spawning nests) in the West Credit River.

The Town of Erin could improve Project design and take other measures to protect Brook Trout habitat and still achieve its growth goals:

  • Include an effluent temperature limit in the Environmental Compliance Approval.
  • Place aeration tanks and clarifiers under high albedo buildings, insulate all pipes and sewers, liquid oxygen for the treatment process, underwater mechanical mixers, etc…
  • Inground infiltration of treated effluent is a viable alternative to discharging directly into the West Credit River, and was successfully done at wastewater treatment facilities in both Markdale (Rocky Saugeen River) and Lucknow (Nine Mile River).
  • Remove 3 upstream dams to significantly lower downstream water temperature and open up additional habitat.

“A state-of-the-art design may not be required everywhere but we should not be destroying the last remaining healthy subwatershed for expediency”, says Jack Imhof, retired Trout Unlimited Canada, National Aquatic Biologist, and renowned fisheries advocate in southern Ontario and across Canada.

The West Credit River is a rare and intact coldwater ecosystem of significance – so please help us protect it!  To learn more about our efforts and how you can help protect West Credit River Brook Trout you can:

This is a guest post by the Coalition for the West Credit River