The street sweeper is an unlikely hero. Rumbling down city streets and boulevards at a leisurely 2-3 miles per hour, these hulking machines are, for most of us, a passing curiosity on an otherwise unremarkable day. As it turns out, however, these busy brooms may hold the key to cleaner lakes and rivers in urban communities around the state.
When it rains, the water that falls on rooftops, roads, and other impervious surfaces flows into storm drains and ditches that carry it onward to lakes, rivers, streams and wetlands. Along the way, this stormwater picks up litter, sediment, salt, engine oil, and organic debris such as leaves and grass clippings. Stormwater is also high in phosphorus, a nutrient that feeds algae and other aquatic plants.
A 2016 study conducted by U.S. Geological Survey (USGS) in Madison, Wisconsin found that nearly 60% of the annual “phosphorus load” from urban stormwater comes directly from leaves that fall onto city streets and sidewalks. The solution? Send out street sweepers and volunteers to collect the leaves before they decompose and cause water pollution.
This winter, the Lower St. Croix Watershed Partnership will allocate $40,000 in state funding to help 16 local communities develop targeted, enhanced street sweeping programs in order to reduce stormwater runoff pollution to the St. Croix River and its tributary lakes and streams. The communities include Afton, Lake Elmo, Bayport, Baytown, Lakeland, Lakeland Shores, Lake St. Croix Beach, Linwood Twp., Marine on St. Croix, North Branch, Oak Park Heights, Rush City, Scandia, St. Mary’s Point, West Lakeland, and Wyoming. In addition, the communities of Forest Lake, Stillwater, and Woodbury are already implementing enhanced street sweeping programs.
Research from the University of Minnesota and Minnesota Pollution Control Agency shows that street sweeping is one of the most cost-effective ways for communities to reduce urban water pollution (see MPCA Street Sweeping Phosphorus Credit Calculator). Street sweeping also helps to extend the lifespan of stormwater infrastructure, reduce maintenance costs, and reduce the risk of localized street flooding due to clogged storm drains.
In Forest Lake, where the city implements an enhanced street sweeping program in partnership with the Comfort Lake-Forest Lake and Rice Creek Watershed Districts, the sweeper collects 309 pounds of phosphorus per year. That’s enough to prevent a whopping 154,500 pounds of algae growth in Forest, Shields, Keewahtin, Comfort, and Clear Lakes! The city’s street sweeping program has earned a City of Excellence Award from the League of Minnesota Cities’ and a Watershed Champion award from the Comfort Lake – Forest Lake Watershed District.
To help bridge the gap between scheduled street sweepings and keep even more pollution out of our waterways, community residents can also adopt storm drains through the Adopt-a-Drain program. Adopt-a-Drain volunteers collect litter, leaves and organic debris from the curbside near their drains and report their cleanings online so that local partners can track the collective impact. To date, Minnesotans have adopted 19,290 storm drains and report collecting 550,458 lbs of debris that would otherwise end up in lakes, rivers and streams.
In some locations, volunteers are even using the program to build friendships with other people in their communities. “It’s really nice being able to regularly connect with neighbors and get some exercise,” says Bonnie Houger, a member of a group that call themselves the Walky-Talkys. “When I learned about the Adopt-a-Drain program coming to Chisago County this summer, it seemed like a great opportunity to also help our environment and protect the lakes.”
Keep an eye out for street sweepers in your city next fall. In the meantime, you can sign-up to adopt a local storm drain at www.Adopt-a-Drain.org.