Manistee Lake Association Home Page
Why Lawn Chemicals Are BAD for Manistee Lake
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- Written by Seth Phillips
- Category: Home Page
Eventually it will warm up (I hope so) and people will turn to taking care of their yards. One of the most important things people living on Manistee Lake can do to protect the lake from degradation is to avoid the use of lawn chemicals on lake front properties. So, you might ask, why are fertilizer and weed killers so bad for the lake? Here’s why.
Let’s start with fertilizer. The main ingredients in fertilizer that makes grass grow are phosphorus and nitrogen. Phosphorus stays on the surface of the soil, so when it rains, it runs off the surface and into the lake. Nitrogen on the other hand percolates down through the soil and into the groundwater where it eventually discharges into the lake. If these chemicals make your grass grow, in the water they also make weeds, including milfoil, grow. They are also the main food for algae. So the more we put in the lake, the more algae we will get when the weather gets warm. Since Manistee Lake is shallow, it is more sensitive to these inputs and warms faster. We spend a lot of money and work trying to prevent the growth of Eurasian milfoil in our lake and every time someone’s fertilizer gets into the lake, it works against this effort.
Knowing all this, fertilizer companies market something they call “lake safe” fertilizer. It is a fraud. While this fertilizer does not contain phosphorus, it still contains nitrogen. It isn’t safe for the lake. If you need to fertilize your lawn, use lake water to water it. There is enough phosphorus and nitrogen in the water already to be decent fertilizer.
TruGreen and other lawn applicator companies claim their sprays are not toxic and only contain chemicals that are government approved, suggesting that means they are safe. Some also assert that nothing they use will get into the groundwater. Well, if they aren’t using nitrogen, then you are paying for fertilizer that doesn’t fertilize.
Now, weed killers. Like fertilizer helps weeds grow, weed killer runs off into the lake and kills aquatic plants. Most lawn herbicides are what are called “broad spectrum”. That means they kill lots and lots of different stuff. . Many of their weed killers use known herbicides. If they kill plants, they must have some level of toxicity. Used properly they may be safe for people and pets, but they will still kill lake weeds if it gets into the water. Many say they only use organic products, as if that is a synonym for safe. In chemistry, organic means built on carbon. You know, like DDT, PFAS and dioxin. You wouldn’t want to consume them. We surely don’t want them in our lake.
While we want to prevent milfoil, and we use a highly selective herbicide in controlled and limited applications to do that, there are native plants, like pond weed, that are essential to maintaining the health of the lake. Broad spectrum weed killers kill these plants too. The native plants help keep the water clear by binding up the sediment at the bottom of the lake including the phosphorus and nitrogen in the sediment. This helps retard algae growth. These plants help oxygenate the lake. They provide important fish cover critical to maintaining our excellent fishery. Killing them might make boating better in some portions of the lake but will result in huge algae blooms later in the summer that will make the lake unusable, will deplete the oxygen in the water and kill off fish.
You live here because of this lake. The Manistee Lake Association and the Manistee Lake Improvement Board are dedicated to protecting Manistee Lake for our future. If allowed to turn into an algae filled swamp you won’t be able to use it and your property values will crash. Is having a suburban lawn up here in the north woods really that important? Please help protect Manistee Lake and don’t fertilize your yard or use weed killer. While you are at it, is your septic system working well? Does it need pumping or repair? Bad septic systems are the other big source of trouble for our lake, but more on that another time.
Want to help let your neighbors know they should not use fertilizer? We have 50 yard signs to help spread the message. Want one? Let me know. I'll get it to you.