Killarney Lake - Bubblers only below
Cyanobacteria blooms in stagnant coves?
To: Residents of Killarney Turtle Mountain
Where should you authorize the "bubblers" be put in your lake?
- On its deepest bottom, near old town drains, under the most open wave action?
- Or, below each blue-green toxic bloom where it initiates along stagnant shorelines?
(In front of homes where kids are at greatest risk of cyanobacteria toxins, via small air pumps.)
Evidence to consider: "Two of the five lakes at Fort Whyte Alive have been aerated for several years, and the one with the longest period of aeration is also the most eutrophic, with massive amounts of Aphanizomenon (cyanobacteria) at times" - lake scientist at U. Manitoba.
Visser et al. 2016 "Artificial mixing to control cyanobacterial blooms: a review." Built on review of over 100 peer-reviewed scientific articles, they concluded "A change from cyanobacterial dominance to green algae and diatoms can be observed if the imposed mixing is strong enough to keep the cyanobacteria entrained in the turbulent flow..." Aeration bubbling directly under the neurotoxin-producing blue-green cyanobacteria blooms was the most energy efficient method of mixing the waters to kill them. You can read this easily via: scholar.google.ca, search for "visser cyanobacteria", then click on "since 2014". (UM engineering scientist forwarded this article to aid our considerations.)
The massive rain storm I observed from my farm in July 2016, travelling from NW to SE over long narrow Pelican Lake, might have flushed it clean as the front of fresh new water of different density moved along it from NW to SE pushing much of the floating algae, cyanobacteria, dissolved toxins etc. out its river exit. But we cannot conclude with certainty that the rain event was the primary cause of perceived improvements in water clarity and fish life, because humans had implemented an aeration treatment that they are convinced was the primary cause.
After a few summers of aeration treatment, the phosphorus levels remained high, and both ends of Pelican Lake were still ordered closed to swimming due to cyanobacteria in 2017, at the same time as were Killarney Lake and Rivers Reservoir. But Killarney Lake starts with much higher phosphorus that many scientists correlate with promoting cyanobacteria, yet has no river exit to drain away organisms, toxins and nutrients, and is below an industrial town over a shallow aquifer contiguous with the lake, resupplying it with the fertilizer nutrients and many toxins spilled in town over the last 138 years.
The Risk in Council's decision: Copied from www.healthylake.ca, the Killarney Lake Action Committee's brochure states the "addition of oxygen is to facilitate more decomposition of the organic matter on the bottom". But its decomposition releases more nutrients such as phosphorus and also sequestered toxins that are currently safely contained in that bottom organic matter, such as plastic microfibers and lead from gasoline exhaust via town gutters, buckshot and fishing weights. The unanswered question: Why position aeration bubblers on the deepest bottom to maximally oxygenate the lake, most distantly from toxin-producing blue-green cyanobacteria blooms, and risk predictable biological release from old organic matter of its phosphorus and its safely sequestered toxins, back into biologically-active lake waters, to then bio-concentrate up the food chain into fish eating families?
I participated on the KLAC committee for about three years. Thanks for that opportunity to assist. This letter fulfills my responsibility to stimulate the best planning to protect children from neurotoxins. Further action is the responsibility of each reader. More discussion is at www.GrantRigby.ca