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Oregon Creek.

Oregon Creek is one of the principal water pathways from the Duluth campus to Lake Superior.

Raindrops keep falling

A new garden at UMD protects Lake Superior

By Gayla Marty

M, summer 2006

When a raindrop falls on the University of Minnesota's Duluth campus, it takes approximately 10 minutes for it to run down the mile-and-a-half slope to Lake Superior.

Forty-two creeks run into Lake Superior within the borders of Duluth, a city built on a sensitive landscape overlooking the largest freshwater lake in the world. And each time another vacant lot is converted into an impermeable surface like asphalt or a sun-baked lawn, storm water runs off faster, dirtier, and warmer into Duluth streams and the lake below.

Last year, UMD took a major step to protect Oregon Creek, one of the principal water pathways from the campus to Lake Superior. A rain garden, right next to UMD's main entrance on College Street, now slows, filters, and cools storm water running off a main parking lot into the creek. It's a project that is helping to make UMD a leader in environmental stewardship.

UMD's rain garden is huge compared to others around the country, covering a third of an acre and able to hold 60,500 gallons. Yet it blends into the landscape so beautifully that, when dry--which it usually is--you might not even notice it, at least for what it is.

In the rain garden, storm run-off fills a bowl-shaped basin--the first-line filter for sediment, debris, and litter--and overflows into the surrounding shallow wetland zone. Water then soaks through the ground, where it is used by plants, held by the soil, or evaporates. Any excess water slowly filters down through the soil and then exits through drain tiles over a small, adjustable dam and into Oregon Creek. The dam is used to hold back rainwater to serve as an underground irrigation system for plants during dry times.

The garden is also attracting visitors. Together, the whole community is watching colors and textures change through the seasons of the garden's first full year, from rusty-toned grasses in March to jewel-colored lilies and sedum in late summer.

Nestled within stands of existing trees, the rain garden added more than 50 species of flowers, grasses, shrubs, and trees--most native to the area--arranged in dry, wetland, woodland, and ornamental zones. Visitors can pick up a brochure from a nearby box and take the self-guided tour. A visit can take as little time as a raindrop's trip to Lake Superior, but you'll want to stay a lot longer.