City of Chanhassen
7700 Market Blvd
PO Box 147
Chanhassen MN
55317
952-227-1100
Fax: 952-227-1110
Disclaimer
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Green Pond Scum
Background
 There are two types of standing water in Chanhassen: natural wetlands and utilized water bodies. A natural wetland is any area that wasn’t created by humans and meets three criteria: water within 12 inches of the surface for 8 consecutive days between April and October, soils that develop under wet conditions, and vegetation that can grow in wet conditions. Some wetlands have cattails and lily pads and provide habitat for wildlife. However, natural wetlands can look like meadows, forests, or anything in between.
Utilized water bodies are created by humans to serve at least one of two purposes: improve water quality, or control water quantity. Utilized water bodies often look like natural wetlands, but they aren’t subject to the same regulations as natural wetlands.
What You Can do to Combat this Nuisance
There are many things that you can do to take revenge on the Green Scum. We suggest these options, as they fight the source of the problem, rather than just the symptoms:
- Stop mowing to the edge! The unmowed area is called a “buffer strip”. It’s the quickest, cheapest, and easiest thing you can do to combat green scum – and it will cut the amount of time you spend mowing! An undisturbed strip of grass at least 5 feet wide between your yard and the wetland will keep the extra nutrients out of the wetland, preventing the scum from growing. This is crucial if you fertilize your lawn.
- Don’t use fertilizer with phosphorus in your yard. Most soils in Chanhassen have naturally high levels of phosphorus. But if you want to be sure, call the City of Chanhassen to find out how to obtain a soil testing kit. Buy only fertilizer that has “0” as the middle number (10-0-5), or ask your lawn care provider to use phosphorus-free fertilizer.
- Be water smart! Give the lawn ½ to 1 inch of water at a time and only when grass starts to curl (before it turns brown). Water during the evening or nighttime hours when water won’t evaporate. Heed the City’s watering restrictions: odd numbered homes = odd days of the month, even numbered homes = even days of the month.
- Place bales of barley into your ponds. Though it sounds strange, it actually works. The actual mechanism of control is not completely understood. The straw decomposes in water when oxygen is available. While it decomposes, the chemicals released kill or inhibit the growth of algae. Also, the microbes involved in decomposition compete with or consume the algae.
To ensure that the microbes living in the barley have enough oxygen to do their work, place only half of the bale into the water and keep them in the shallow area. About 2 bales per acre of water are needed for this process, and it can take up to 30 days to see results.
The scum floating in these water bodies is algae. In balanced aquatic systems, algae provide food for organisms. However, high levels of nutrients (like phosphorus) upset this balance and cause algae populations to grow quickly. When algae die, they decompose and create an offensive odor.
But how does the phosphorus get into the wetlands? It comes from yards and storm sewers. Sometimes people dump yard waste (like grass clippings, leaves, branches, or weeds) into the street or directly into the water. When yard waste in ponds breaks down, it releases nutrients.
Contact Information
Water Resources Coordinator
City of Chanhassen
Phone: 952-227-1168
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For more info on Barley Straw:
Blue Water Science
Steve McComas
550 South Snelling Avenue
St. Paul, MN 55116
Phone: 651-690-9602 |
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