Pre-Memorial Day Algal and Aquatic Vascular Plant Assessment

Though Mother Nature gave us a less than ideal day for it, yesterday we were on the Main Lakes to evaluate the May 17 Curly Leaf Pondweed Treatment performed by Aquatic Nuisance Control. We were pleased to see Curly Leaf plants in the smaller treated patches were highly stressed and starting to fall out. Plants in the larger patches were looking more intact but the true results of the effectiveness of the treatment will be witnessed this fall when the plants re-emerge during the second stage of their life cycle. It appears this spring's treatment was successful and die-off is occuring before they could flower and produce more turions (root bulbs).

Filamentous algae blooms were witnessed at or near treatment levels in three locations on the Main Lakes: Near the deep well pump at Buchanan and West Royal, Near the deep well pump by the new medical center, and behind Country Corners. All three areas will be treated after the Holiday weekend. What is causing these isolated algal blooms? The algal growth behind Country Corners is likely related to high nutrient spring runoff from the parking lots. The snowmelt and first rains of the spring rinse salts and fertilizer residues off the parking lot, throughout the drain and out into the lake. The nutrients are utilized primarily by quick, out of the gate algae as the vascular plants don't "wake up" and start taking in nutrients until later in the season (typically in May). Yesterday we noticed the native Illinois Pondweed, Northern Milfiol, Coontail, Elodia and others were growing nicely. The plants are waking up just in time to provide cover for all the juvenile bass, bluegill, perch, crappies, minnows, and other fish that are just about to be produced by spawning parents.
Algal growth around the deep well pumps is from recycling of nutrients deposited in these areas over the years. Water coming from the deep wells is high in phosphorus (60-70+ ppb phosphorus). In most lakes, phosphorus is the most limiting factor to plant and algae growth. Remember, at just 10 ppb phosphorus in lake water, plant and algal growth can be stimulated. When the pumps are run, the phosphorus contained in the water is quickly taken up by plants and algae in the vicinity, hence the algal blooms and large dense patches of vascular plants witnessed around the pumps. Treating these areas with the non-selective algaecide copper sufate provides only very temporary relieve of the symptoms as the nutrients released from dying algae can quickly be utilized by new colonies that bloom shortly there after. This relationship demonstrates the importance of a healthy native aquatic vascular plant population. The nutrients in a lake have to be used by something. We are managing for the nutrients to be locked up in low growing non-nuisance native vascular plants. To reduce phosphorus loading, the CLPOC leadership is utilizing the Lake of the Clouds pumps to maintain Main Lake water levels. Ground water from these pumps comes from a much less organisms influenced aquifer (5-6 ppb phosphorus).
We are conducting a study to monitor the environmental impact this strategy will have on Lake of the Clouds and the Main Lakes. Water samples were drawn from these areas for phosphorus and nitrate nitrogen analysis. Three runoff samples were also collected from Bill Hull and his team. These samples will be analyzed to determine if golf course runoff is negatively influencing the water quality of the Little Muskegon River. If such influence is detected, actions will be taken to minimize the effects.
One closing thought. While out yesterday, we noticed a fair amount of tree pollen on the water surface. At first glance, this pollen appears much like floating clumps of filamentous algae. I mention this because it is important to distinguish the difference. Floating clumps of filamentous algae meet the criteria for spot treatments with algaecide. Clumps of tree pollen do not. Applying copper sulfate to tree pollen and tree debris on the water surface would not only be a waste of C.L.P.O.C. dollars, it would be detrimental to our goals of maintaining high water quality and biological integrity of the lakes. In isolated areas where pollen and debris blow into and accumulate into thick mats, they may give rise to filamentous algal blooms as the pollen decays and releases nutrients. If this is observed, these areas will be treated with haste.
Thank you for your emailed comments and questions. Your interest in your lakes is impressive and critical to their preservation and enhancement. Never hesitate to contact us throughout the link on this page. We hope the forecasted wet weather doesn't keep you from getting out to enjoy your lakes this holiday weekend. Your Lake Managers, Joel and Tom