The plot thickens: a green alternative for stormwater management

At the University of Illinois Urbana-Champaign, fans of the men’s basketball team enjoyed March Madness as they saw the Illini reach the Elite Eight during the NCAA Tournament.

But another kind of March Madness was happening on campus – the Rain Garden Rumble at the Red Oak Rain Garden. During this competition, people voted on social media for their favorite native plants, which were entered in brackets similar.

 It was a fun way to promote the Red Oak Rain Garden, a project aimed at promoting sustainability on campus. The garden also is one example of how rain gardens can address stormwater issues associated with climate change. 

A rain garden consists of a shallow depression about six to eight inches deep. It holds water for a short period of time, allowing it to be absorbed into the soil. It improves water quality, reduces flooding and builds resilience to climate change.

The Red Oak Rain Garden was built using grant money, student labor and the contributions of such local volunteers as the Champaign County Master Gardeners and the East Central Illinois Master Naturalists. It is located on the U of I campus between Allen Hall and the McKinley Health Center, at the junction of five sidewalks in one of the main ways that pedestrians are able to access campus.

It was first created in 2007 and then renovated in 2019 with the goal of fixing flooding issues that affected the sidewalks and threatened a large red oak tree.

The red oak is a tree that “doesn’t like to have wet feet,” said C. Eliana Brown, water quality and stormwater specialist with the University of Illinois Extension and the Illinois-Indiana Sea Grant. “And wouldn’t you know it, all the water was pooling right around the red oak and it was seeing effects on its health.”

The garden’s ground cover of native plants acts as a small-scale wetland, absorbing and filtering rainwater runoff, which mitigates flooding and improves water quality.

“You’re not only getting clean water, you’re doing it with native plants,” Brown said.

In Chicago, extreme rains place a burden on the city’s combined sewer system, which handles both sanitary wastewater and stormwater.

“Basically, it will rain even more. Water has to go somewhere,” Sybil Derrible, professor in the department of Civil, Materials, and Environmental Engineering at the University of Illinois Chicago, said. Humans, however, have complicated things “by paving things over, by putting in concrete, which means that those surfaces are now impermeable” and it can’t penetrate into the ground. “Water always flows from a higher elevation to a lower elevation, which means that we have built streets in such a way that rainwater flows to sewers, and all of a sudden sewers get all this incoming rainwater it just cannot handle.”

One example of a rain garden in Chicago is the Argyle Shared Street in the Asian Uptown neighborhood. Water goes to a patch of planters, where it is held before it travels to the sewers.

“There has definitely been much more of a focus on green infrastructure in the last several years,” Kate Evasic, a senior planner at the Chicago Metropolitan Agency for Planning (CMAP) who specializes in equitable climate resilience and water resources, said. Chicago and other municipalities have increasingly pursued green infrastructure solutions using public dollars and grants, she said.

“We’re past the rain garden pilot phase,” she said. “We know it works. We just need more of it.”