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Uppity Wisconsin - Progressive Webmasters

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October 15, 2007


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Dan Sebald

To see all the trash floating amongst the putrid algae blooms this past summer near the Terrace swimming area of the University of Wisconsin, home of the Gaylord Nelson Institute for Environmental Studies, makes one want to cry.

From what I've seen, there are several who really take the issue to heart and are in positions to run with the idea of really cleaning up the Yahara Lakes in terms of pollution, eutrophication and invasives (county and DNR). Unfortunately, the political will isn't there to provide the financial backing and authority. The progressives on the C.C. did do a little about five years ago, but that's not enough.

It's strange, really, how people place more importance on possessive things than on something like Lake Mendota (known as Wonkshekhomikla to those who walk the land before us), which has been around thousands of years.


I am 100% in favor of serious and sustained efforts to clean up the lakes here, and will do whatever I can to help make that happen. Do we start a petition? Call our reps? I'm honestly curious about what actions might be most effective in getting this done.

One thing about the Zaleski article concerns me, though: the use of aluminum sulfate to treat lakes. In theory, it sounds good: bind up all that phosphorous and other solids and get 'em out of the way. But what are the long-term environmental effects of pouring all that aluminum into the water?

So far, I've found this:

"However, the use of aluminum sulfate as an additive has inherent problems when employed in lake water having low alkalinity and low pH, as aluminum sulfate tends to further depress the pH of the entire lake. For example, one mg/liter of aluminum sulfate consumes about 0.5 mg/liter of alkalinity from lake water, thereby depressing the pH of the lake. Lake pH is of particular importance because at a pH of 6.0 or less, free aluminum becomes soluble and enters the lake water. Toxicity tests have indicated that aluminum concentrations in water which are greater than about 50 µg/liter are detrimental to aquatic life." (

And then: "However, in eutrophic lakes algal blooms often raise the pH to 9 or above, and a significant fraction of the ammonia is thus present as volatile NH3. The pH of the Lake Mendota surface water is generally 8.9 to 9.0 during the summer. However, ammonia is depleted to trace concentrations (0.01 to 0.05 mg. of N per liter) by algal assimilation in early spring and remains low in concentration until late fall. During periods when the surface water ammonia content is high (0.3 to 0.4 mg. of N per liter) the pH is near 8.0, and during much of the period of high ammonia values, the lake is ice covered." (

Which would indicate that at this time, with the lake pH level being as high as it is, likely due to all that algae, adding the aluminum sulphate would be relatively safe. But what about if/when we reach the goal of cleaner lakes, resulting in fewer algae blooms and, presumably, lower pH levels? Would the aluminum then be released into the water?

I would hope that any task force created to study and make recommendations for the cleaning up of the lakes would seriously address this issue before using the technique. I wonder what the Minnesota planner's knew about the process?

I realize this makes me geeky and picky, but it seems important to know.

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