Algae attacking Lake Okabena, area lakesWORTHINGTON — When August rolls around, some very undesirable odors start to show on and around our area lakes. This smell can drive you far away from the water if it is intense enough. The smell I am referring to is the smell of dead and decaying algae that starts to accumulate on the down-wind shorelines as August continues to progress.
By: Scott Rall, Worthington Daily Globe
WORTHINGTON — When August rolls around, some very undesirable odors start to show on and around our area lakes. This smell can drive you far away from the water if it is intense enough.
The smell I am referring to is the smell of dead and decaying algae that starts to accumulate on the down-wind shorelines as August continues to progress. This phenomenon occurs regularly in almost all prairie lakes in southwest Minnesota and northwest Iowa in August and September.
The cause of this event is attributed to nutrient-rich water and warm temperatures when accompanied with little or no wind. Algae is present in the waters year-round and can be as simple as single-cell bacteria to multi-celled filaments to large lake weeds. The unusual thing about algae is that it has no roots, and it produces no flowers and no seeds. Algae is absolutely necessary and serves as the foundation of the food chain. A lake ecosystem cannot survive without any algae. The key is to have just the right amount. Our lakes have far too much algae — the result of years of phosphorus loading from soil erosion. It also can be from agriculture sources and fertilizer run-off from city lawns.
In the old days, the municipalities dealt with the algae problem by adding a chemical to the water called “copper sulfate.” This comes in many forms but was in a small pellet form and was spread around the lake by boat. This chemical killed the algae with generally good success, but the problem with this method was that it killed many other desirable things as well.
Examples of good things that died with copper sulfate were snails, invertebrates and beneficial aquatic plants.
Copper sulfate usage has been almost discontinued for a variety of reasons.
They include the fact that it is a non-specific poison that kills both plants and animals, and the difficulty of even application at rates effective to kill algae without disrupting the lakes’ ecosystem. Although not the greatest factor, cost has become an issue. If your algae problem requires a heave dose of this chemical, the cost to treat a lake the size of Lake Okabena can quite easily run upward of $22,000.
The major emphasis of algae has gone from treating it to trying to prevent it. This is done by many methods, but they all have the goal of reducing the transportation of phosphorus into the lake. Grass buffer strips and wetland restorations are the projects that are the easiest to see, but other efforts include rain gardens, storm water retention ponds and something as simple as street cleaning. Everyone can do his or her part. Don’t mow your grass into the street, because the grass washes into the lake. The grass contains phosphorus, and, as you know, phosphorus is bad for the lake — especially if you hate algae blooms as much as I do.
Take a minute to read the insert that was in your last Worthington Public Utilities bill. It contains many helpful hints that can make a difference over time. If you did not receive one, you can request a copy by accessing the City of Worthington’s Web site at http://www.ci.worthington.mn.us/stormwater/Fact_Sheets/Polltion_And_Algae_Connection_Factsheet.pdf. This is a really long address, but all you have to do is drive around Lake Okabena — or any area lake, for that matter — and you will immediately be reminded why it might be worth the effort.
Our lake didn’t get in this condition overnight, nor will this same problem be solved in that same timeframe. It will take years to correct the problem, but if you don’t start now you will never see the benefits in the future. I don’t live on a lake, but this over-abundant algae problem affects everyone. Minnesota’s waters are supposed to be blue. We are not known as the Land of 10,000 Green, Stinky Lakes. Water is such a valuable resource that we all need to put forth the effort it takes to protect and preserve it.