Safe Lawn Weed Control Around Lakes and Rivers

Balance a beautiful lawn and yard with clean water best practices by following this advice from pros in the know.

Deciding how to safely weed or fertilize your lawn can present plenty of challenges in any yard, let alone one adjacent to a waterway. If your primary residence or your summer home/cabin is near a lake, stream or river, you should know that lawn-care chemicals used to wipe out tough weeds can also be toxic to humans, pets, other wildlife and plant life.

“Generally, the biggest issue is you don’t want chemicals and physical items such as clippings or leaves to be in the water body,” says Kirsten Barta, a trained aquatic biologist and program coordinator for the Minnesota Pollution Control Agency.

The problem, Barta says, is multifaceted. “The chemicals tend to be very water-soluble and contain toxic compounds that directly harm aquatic life, as well as nutrients (phosphorus and nitrogen) that will increase algae/plant growth,”.she says“That growth then dies and the bacteria breaking it down take all the oxygen out of the water, killing fish and other organisms.”

Barta adds that many fish and aquatic invertebrates are so sensitive to their surroundings that “it doesn’t take a large amount of change to kill them.”

When you see lakes and other bodies of water with that pea-soup appearance, Barta says that’s a sign of nutrients being present that the aquatic system isn’t meant to handle. Nitrogen and pesticides can also poison humans and contaminate groundwater and wells, especially shallow or sandpoint wells. The solution to this is to find the best weed killers that won’t kill grass.

Why Use Eco-Friendly Weed Killers Near Lakes?

“Pretty much any improperly or over-applied lawn care product can harm the environment, even non-toxic ones,” Barta says.

One way to identify the right treatment is to do a soil test, which can help avoid overuse or misuse. “The key is to use the bare minimum, if any at all,” says Steve McComas, The Lake Detective and owner of Blue Water Science.

Products that can harm lakes and rivers

Barta says these products and chemicals should be avoided if you live near a waterway:

• RoundUp. This product is not federally approved for use near water. It may contaminate drinking/potable water sources and is readily water-soluble. “So while it may take care of weeds, it will also kill any shoreline plants,” Barta says.
• Any fertilizer containing phosphate. Runoff into lakes will cause algae blooms.
• Weed-and-feed products. These generally contain way more fertilizer and herbicide than needed and both are readily water-soluble.
• Glyphosate. This is a common ingredient in a lot of herbicides. But it’s not a targeted weed killer—it also kills good aquatic plants.
• 2,4-D. A common ingredient in weed-and-feed products, it is also a known carcinogen and toxic to aquatic life.
  For additional pesticide resources, Barta recommends the National Pesticide Information Center.

Best Practices for Safely Removing Weeds

So, what does work safely? “Good old hand-pulling is always a good option,” says McComas.

Besides that, Barta suggests a few other waterway-safe lawn care practices that are the best weed killers that won’t kill grass:

• Instead of herbicides, put down mulch or weed suppression mats around landscaping.
• Let the grass grow a little taller—about three inches is ideal for most kinds of lawn grasses. This reduces the need for weed killers and can protect grass during droughts and other stressors.
• If you decide to use an herbicide or fertilizer, start with the lowest toxicity possible and wait the entire recommended time frame for it to work. Not all herbicides work immediately.
• Avoid putting down herbicides or fertilizer before a predicted rainfall. And be aware of slopes where the chemicals can be washed down into sewers or waterways.
• Use products that contain organic or natural ingredients, but be aware that over-application or direct application near water or well heads can still be harmful.
• Combine one gallon of standard white vinegar, one cup salt and one tablespoon of liquid dish soap to create a safe weed-killing formula. Stir vinegar and salt together until salt dissolves, then add dish soap, which helps the solution stick to the plant leaves. Put the mixture in a spray bottle and spritz on weeds. Barta says it usually takes two to three days on average to work, depending on the plant species.

Waterway-Friendly Lawn Care Practices

There are a few other things to consider when trying to beautify yards while protecting waterways. Barta suggests:

• Collect grass clippings and leaves to properly dispose of them as yard waste. Burning leaves creates toxic smoke. Clippings or leaves can run off into lakes and streams, or into storm sewers that drain directly into bodies of water and streams. You can add grass clippings to your compost, or put them down on top of newspaper or paper bags to act as short-term mulch in weedy areas.
• Pick up and dispose of pet waste. The nutrients and bacteria cause water pollution and are a human health hazard.
• Consider growing a buffer of native plants or tall grasses along the shoreline to filter runoff, prevent erosion and provide wildlife habitat.

FAQ

What is the best weed killer that won’t kill grass?

First you need to understand which type of weed you are dealing with. There are specific types of products for specific types of weed like if it is broadleaf or grassy. Some brands like Ortho Weed B Gon Max and Ferti-lome Weed Out Lawn Weed Killer are considered to be effective against broadleaf weeds. In the case of grassy weeds, products like Roundup For Lawns (formulated specifically for lawns) can be used on certain grass types.

How do I control weeds safely near a lake?

The best practice in this case can be prevention of the growing of weeds. If not possible then using natural weed killers like corn gluten meal or vinegar salt is the best option. If in case they are not working then choosing a low-toxicity herbicide can also be a good decision. But the best thing is to use natural methods like manual removal.

About the Experts

• Kristen Barta is a Program Coordinator at the Minnesota Pollution Control Agency. She holds the responsibilty as a coordinator of the water quality certification program. Previously she was an environmental review project manager. Before that she worked on projects related to soil and water conservation. She had also worked as a fish biologist. 
• Steve McComas, widely known as The Lake Detective, is the owner of Blue Water Science and a leading expert in lake and pond restoration. With over 40 years of experience, he’s authored multiple handbooks and conducted hundreds of ecological studies on aquatic systems.

Sources

• North Shore Land Alliance: “Water Friendly Lawn Care Tips” 
• NPIC: “National Pesticide Information Centre”
• Facebook: “Blue Water Science | Saint Paul MN”