Rain causes visible problems to our lakes

Wednesday rain causes visible runoff into Lake Mendota

Recent heavy rain storms flush algae-causing phosphorus through storm sewers into lakes

MADISON, Wis. — Heavy rain events over the past two weeks in the Madison area are setting up its lakes for toxic blue-green algae blooms in the coming months. With one pound of phosphorus having the capability to create 500 pounds of algae, the need to slow or divert runoff is imperative.

“The heavy rain storms we’ve had over the past several weeks have made harmful runoff issues visible to the naked eye,” says Clean Lakes Alliance Executive Director James Tye. “From our Foley & Lardner donated offices in Verex Plaza next to James Madison Park, we’ve witnessed huge plumes of sediment wash into the lake multiple times over the past few weeks.

What Will Happen

Last year blue-green algae blooms closed beaches in mid-June and early July along the southern end of Lake Mendota. Three main contributing factors were phosphorus runoff, heat, and low wind. Blue-green algae blooms affect water clarity and are a health hazard to both pets and people. “The runoff we’ve seen over the past few weeks will almost certainly contribute to any blue-green algae blooms we will see in the coming weeks,” says Tye.

How To Help

Our climate has changed drastically over the past 30 years, which has brought more intense rain events in the spring and summer. While we can’t quickly reverse climate change, we CAN reduce runoff issues.

One way to combat the runoff brought on by these rain events is to increase permeable surfaces and to slow the water before it reaches the lakes. Homeowners can invest in rain gardens, rain barrels, and maintaining protective grass cover over bare soil to help in urban areas. More resources are available at cleanlakesalliance.org/what-can-i-do.

With spring and summer road and building construction, preventing jobsite runoff becomes equally important. All sites are expected to have a construction site erosion control plan. If residents see a site that doesn’t appear to be effectively using erosion control measures, the City of Madison encourages anonymous reporting at: cityofmadison.com/reportaproblem.

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