Not Just Flowing Waters . . .

by | Mar 6, 2024 | Chapters, News | 0 comments

No Just Flowing Waters…
Written by: Peter Little
Northern Lights Fly Fishers Chapter Executive Member

A common misperception of Trout Unlimited Canada (TUC) seems to be that its work and interest are focused just on Canada’s rivers and streams and the fish and aquatic insects that inhabit them. That’s not surprising when, for example, Merriam-Webster dictionary defines ‘coldwater’ as ‘’running water”. Yet Canada’s lakes and ponds and their aquatic life forms are also an integral part of TUC’s mission “to conserve, protect and restore Canada’s freshwater ecosystems and their coldwater resources . . “

The health of these waters, including those that are stocked with cold water fish species, primarily trout, are becoming of increased concern to organizations like TUC, Alberta Conservation Association (ACA), and others, including the approx. 2.6 million Canadians who go fishing each year. Many of these lakes tend to be shallow, enriched with nutrients, and have seen an increase in water temperatures in the last few years. Many of the ‘aquatic resources’, especially trout, don’t like it! The level of dissolved oxygen (DO) that they need to survive is inversely related to the water temperature, so as DO levels decline, the fish become stressed and in some cases are unable to survive beyond mid-summer. It’s especially so if the water is stagnant and has a lot of rotting, organic material in it. Lake aeration helps, but even with that, some lakes experience a decline in DO by mid-summer that trout cannot survive. And the problem seems to be becoming more prevalent.


The Northern Lights Fly Fishers (NLFF) Chapter of TUC, based in Edmonton, Alberta, became very interested when it heard of ACA’s efforts to address the low-oxygen issue. After a thorough review of the research, ACA fisheries biologists decided to try treating one of the ponds on its trout stocking list with a carefully determined amount of alum to see if that might improve the water quality and help maintain a sufficient level of DO to enable year-round trout survival. When alum is added to water it reacts with the phosphorous and other pollutants causing them to clump together and settle to the bottom of the pond. This process, known as flocculation, helps to remove suspended particles from the water and reduces nutrients available for plant growth. Fewer growth results in less organic decay and thus less of that much-needed DO being used up by the decay process.

NLFF offered volunteer help and successfully applied for an ACA Conservation, Community, and Education grant to help with the costs involved. Rainbow Park Pond in Westlock, Alberta, a popular stocked fishing pond but with a history of winterkill and low fish survival in the summer, was selected as the test site. NLFF then provided local information on the project via the media. It also collected temperature and alkalinity data on several other stocked ponds in the greater Edmonton region which further evidenced similar adverse conditions for trout.

So far, it’s looking promising for improved water quality at Rainbow Park – alum treatment has reduced total and dissolved phosphorus concentrations. However, the benefits of the alum treatment won’t be fully known for a few years. There’s a lot of decaying material from previous years to work through, but hopefully, DO concentrations through this winter will be higher than in previous years and algae growth will be less next summer, both of which are necessary to restore this pond as a viable, year-round, trout fishery.

Although it’s not the health of flowing waters that the project is trying to restore, it is certainly an attempt to find a way to restore a freshwater ecosystem and its coldwater resources. That it’s a partnership between different organizations with similar goals is a bonus for the conservation of trout-friendly waters and Alberta’s anglers.


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