A good Midwestern summer storm can dump a lot of water in one place. Sometimes there’s so much rainwater, it overwhelms the underground sewage pipes. The rainwater mixes with untreated sewage and washes into lakes and rivers. Cities around the country are each spending millions of dollars to solve the problem. In one city, officials are encouraging people to build “rain gardens.” The perennial gardens are designed to hold rainwater and let it seep gradually into the ground. In another installment of the Great Lakes Radio Consortium’s “Your Choice; Your Planet” series… Stephanie Hemphill reports:
A good midwestern summer storm can dump a lot of water in one
place. Sometimes there’s so much rainwater, it floods into the
underground pipes that carry sewer waste. It mixes with untreated
sewage and washes into lakes and rivers. Cities around the country
are each spending millions of dollars to solve the problem. In one
city, officials are encouraging people to build “rain gardens.” The
perennial gardens are designed to hold rainwater and let it seep
gradually into the ground. The Great Lakes Radio Consortium’s
Stephanie Hemphill reports:
The sewage treatment plant sits right on the waterfront of Lake
Superior in Superior, Wisconsin. You can see treatment tanks and
pump houses at the edge of the lake, and lately you can also see
gardens. They’re demonstration plots, showing how homeowners
can help solve a serious problem. Each garden is like a shallow
bowl; about six inches lower than the surrounding ground. The
buildings next to the gardens have down spouts that carry water from
the roofs right into the gardens.
Charlene Johnson is creating these rain gardens. She digs away the
surface soil, adds compost, and then plants native grasses and
“We’ve got the Golden alexander starting to bloom, this one has
purple coneflower, Green-headed coneflower, Cardinal flower, the
They’re pretty and they’re all plants that can live with a lot of water, or
just a little. Johnson says they do a much better job of holding onto
rainwater than a regular lawn, because they have deep roots.
“You know, the average lawn is about 1-2 inches. Therefore you’d
only have one or two inches of roots. Roots equal storage capacity.
Also as the roots penetrate through the ground, they die back, and
those holes can also be used for storm water retention.”
That helps keep some of the rainwater from rushing into the sewer
system. Johnson would like it if every yard in Superior had a rain
garden. The ideal size depends on the size of the house and the
type of soil in the yard, but they’re usually about the size of a small
A lot of us are building water gardens these days – small pools or
ponds – but a rain garden is different. It’s not designed to hold water
or goldfish. It’s designed to absorb big rains and let them sink slowly
into the ground.
“Plants and soil naturally cleanse pollutants from water. By the time it
recharges into the groundwater aquifers, the water is essentially
Charlene Johnson says rain gardens cost about the same to build as
any other perennial garden – between $3 and 5 a square foot. Most
of that is to buy plants, so it’s a one-time purchase. Even if it’s not
that expensive, you might be thinking it’s still a lot of money just to
help the city save on treating sewage, but Johnson says it can pay off
in the long run, because keeping rainwater out of the sewage
treatment system, means the city won’t have to treat as much
volume. That saves money and keeps your monthly sewer bill lower.
Your rain garden will also help the environment by keeping the rush
of water from overwhelming the sewer system and sending it into the
river or lake near your home.
On the other side of town, Jan Murphy says she loves her rain
garden. She built it seven years ago when she built her bookstore
and coffee shop in Superior.
(sound of blackbird)
“We’ve had ducks. That’s a baby redwing blackbird I believe, it’s
been very delightful. We’ve had lots of little critters in here from time
to time. ”
Runoff from the bookstore parking lot flows into the garden, where the cattails and other
native plants clean it up before it seeps into the city storm water system. Now, if you and
your neighbors build rain gardens, it still might not completely solve your city’s problems
with storm water runoff, but the experts say it can help.
Kurt Soderberg directs the Western Lake Superior Sanitary District in
Duluth. He says rainwater picks up all kinds of pollution as it flows
across parking lots, streets, and yards, and eventually into rivers and
“Rainwater is a big impact on water quality. Whether it’s sediment
washing into the lake, whether it’s fecal coliform going into the creeks
and the lakes, there are a whole lot of reasons why you want to stop
storm water from rushing into the natural bodies of water. ”
Soderberg says rain gardens can filter and clean the water before it
reaches lakes and rivers. A lot of cities are spending millions of
dollars each, trying to keep storm water from overwhelming the sewer
system. Soderberg says rain gardens could be part of the solution.
For the Great Lakes Radio Consortium, I’m Stephanie Hemphill.