Will your cottage lake go green this summer?

By Penny Caldwell »Penny Caldwell

New treatment on the way for algal blooms

April 19th, 2012


Photo by Michael Meiters

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Guest post by Blair Eveleigh, senior associate editor

The few warm days this spring have got everyone excited about the warmer weather we expect to come. We’ve even broken some high-temperature records this spring. Makes you wonder how hot this summer will turn out to be. For some of us, it will never be too hot, and we soak up the sun as much as we can (short of melanoma-level exposure, of course). But abnormally high temperatures have another side effect that we’d all like to avoid: algae blooms, especially the toxic blue-green kind. It’s not just hot weather that triggers blooms, though. Here’s how Ray Ford described it in his story on cyanobacterial blooms in Three Mile Lake, from our May 2006 issue:

…given the right circumstances – often shallow, soft-bottomed lakes with limited water movement and balmy weather – cyanobacteria are primed for rapid growth. Their only additional need is phosphorus, and humans do a good job of supplying it. Phosphorus comes from animal and human waste, lawn fertilizers, and whatever ends up in septic systems, including automatic dishwasher detergents and household cleaners. We also help the nutrient get to the lake by clearing land and replacing the tangle of shoreline vegetation with lawns and imported beaches.

Algae blooms have been happening more and more over the last few years, so get ready for a new crop of them this summer. Every new cottage squeezed on to an already overcrowded lake, every newly “cleaned-up” shoreline, every additional dishwasher—all these things contribute to the phosphorus load in our lakes, making the problem more intractable.

Now an Australian company is selling a solution of sorts: Phoslock, a modified clay product that, when added to a body of water, binds to any phosphorus in it and then sinks to the bottom, leaving the water virtually phosphorus-free. The product appears to have passed extensive eco-toxicity studies and has been used in Australia (where it was developed by that nation’s national science agency) and several Asian and European nations. Phoslock is undergoing a pilot project in Lake Simcoe right now, and could soon be in use in Georgian Bay. The Township of the Archipelago is proposing to deposit 60 tonnes of Phoslock into the northern basin of Sturgeon Bay, where there have been algae blooms in the past. If approved, the dumping would start in the summer of 2013. When Ray Ford’s story came out six years ago, an artificial water-circulation system was being proposed (to mix oxygen through the water and keep phosphorus from being released from sediment), but this new added clay solution sounds simpler and may even be more effective. Time, and testing, will tell.

What do you think? Should we continue to develop our cottage-country waterways and then soak up the added phosphorus with clay? Or should the authorities crack down on development, be more forceful in restricting what goes into the water? Meanwhile, there are some things you can do now to reduce the amount of phosphorus you put into the lake.

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Penny Caldwell