TOPICS > Science

Seattleites Construct Rain Gardens to Curb Pollution From Stormwater Runoff

December 8, 2011 at 12:00 AM EDT
In an effort to curb pollution from stormwater runoff, Seattle residents have begun a campaign to build 12,000 rain gardens around the Puget Sound. Katie Campbell of KCTS 9 reports.

JUDY WOODRUFF: Now for those stations not taking a pledge break, we look at efforts in Washington state to curb pollution from stormwater runoff. This report is from Katie Campbell at our PBS partner station, KCTS 9 in Seattle.

KATIE CAMPBELL, KCTS 9: As much as 40,000 metric tons of oil and grease enter Puget Sound every year. That’s as much as a battleship weighs. You might think all that pollution comes from the usual suspects — cargo ships or factories.

But actually it’s caused by rain. Even a light shower can create thousands of gallons of stormwater that washes over Seattle’s nonabsorbent streets, sidewalks and parking lots, sweeping up an array of pollutants and turning into a river of oil, metals, pesticides and other contaminants.

It’s estimated that 75 percent of the toxic chemicals in Puget Sound are carried there by runoff.

CURTIS HINMAN, Washington State University Extension: Many people in the Puget Sound region think that Puget Sound’s in pretty good shape. We have actually some of the worst stormwater and other pollution problems in the United States in Puget Sound.

KATIE CAMPBELL: Residents across the Northwest are taking on the problem by capturing the runoff while it’s still a trickle by disconnecting their downspouts and sending the water to something called a rain garden.

STACEY GIANAS, Stewardship Partners: A rain garden is a beautiful landscape feature you can put in your yard at home to collect rainwater runoff from your rooftop, your downspouts, driveway, any hard surface. And the plants and soil in the rain garden will filter out any pollutants found in that runoff and slow it and divert it before it goes in the storm drains.

KATIE CAMPBELL: Rain gardens are shaped like a bowl and filled with layers of spongy soils and plants that can withstand extreme wet and dry conditions. These gardens are built to mimic a forest and replicate the work of the thousands of acres of woodlands and wetlands that have been lost to urban development.

Washington State University, along with the non-profit group, Stewardship Partners, are working with communities across Puget Sound to build 12,000 rain gardens in the next five years.

STACEY GIANAS: Twelve thousand rain gardens will absorb approximately 160 million gallons of stormwater each year.

KATIE CAMPBELL: The campaign is identifying waterways where stormwater pollution is at a critical level. Longfellow Creek, which runs through the North Delridge neighborhood of West Seattle is one such location. This stream is so polluted by runoff that 88 percent of Coho salmon that come here die before they can spawn.

DAVID HYMEL, Rain Dog Designs: I think we’re going to get started, so…

KATIE CAMPBELL: David Hymel taught the residents of North Delridge how to design and build effective rain gardens. This cluster of gardens was funded by a National Fish and Wildlife grant with the hope that once these 10 rain gardens are built, they will inspire other homeowners to build their own.

DAVID HYMEL: We found it very important to recruit this homeowner advocate, or we call them the champion, who we educate about the benefits and the need to do rain gardens. And we ask them to go find other neighbors.

KARRIE KOHLHAAS, Seattle resident: We cut holes in the burlap.

KATIE CAMPBELL: Karrie Kohlhaas had become the rain garden champion of North Delridge.

KARRIE KOHLHAAS: I don’t think it would have worked if someone had just, you know, shown up and said, we’re putting rain gardens in on your block. It just — people resist that kind of thing.

KATIE CAMPBELL: But Karrie quickly sold everyone in her neighborhood on the idea. Everyone, that is, except her fiancé.

KARRIE KOHLHAAS: And I said, you know, this one neighbor really doesn’t want a rain garden. And, you know, he just really likes his lawn. And Todd said, “That’s how I feel.”

TODD MARTIN, Seattle resident: My initial reaction was, it meant more work for me, because I just finished building a raised bed. So I wasn’t that excited about it.

KATIE CAMPBELL: There are many misconceptions about rain gardens. People wonder if they’ll cause flooding or if they’ll become mosquito breeding grounds, or if they’ll be fussy to maintain. But according to the rain garden experts, these are all myths.

CURTIS HINMAN: Probably the biggest myth is that you can’t use these systems or bioretention areas, rain gardens, on poor soils, soils that don’t drain well. And, actually, you know, we’ve applied and installed, you know, designed and installed bioretention systems on poor soils. And they work pretty well. Very well, actually.

KATIE CAMPBELL: Curtis Hinman is the director of Washington State University’s low impact development research program, a one-of-a-kind in the nation facility for testing sustainable stormwater methods like rain gardens and porous pavement.

CURTIS HINMAN: Right now we’re focusing on water quality treatment through bioretention systems or rain gardens.

KATIE CAMPBELL: Some have questioned the effectiveness of these methods, especially after problems arose with some rain gardens in Ballard last year.

But Hinman says that was a combination of poor soil, groundwater being too close to the surface and mistakes that were made during construction.

CURTIS HINMAN: Ballard rain gardens, I think, are a very good example of how important it is to do really careful analysis, particularly in challenging settings.

KATIE CAMPBELL: Hinman has written the handbook on installing rain gardens in the Northwest, and his research is being used throughout the region as new stormwater management rules are being drafted.

CURTIS HINMAN: In the past, we’ve provided a, you know, a drain and a way for water to get off the property. And as long as water went down that drain, that’s probably all people cared about. Now we’re building stormwater management facilities in their yards, in their — in their streets. And so there’s much more interaction with the public in managing stormwater.

KATIE CAMPBELL: Right now, the state is in the process of adopting new rules to request developers to use sustainable stormwater methods, also known as low impact development.

CURTIS HINMAN: This is a big transition and we’re one of the few regions in the United States that are now requiring low impact development as the first choice for stormwater management.

KATIE CAMPBELL: But for neighborhoods that are already established, it’s a matter of choice to adopt new stormwater management methods like rain gardens. So financial incentives are being offered to homeowners who build rain gardens, in the form of grants, like the one for Karrie Kohlhaas’ neighborhood.

KARRIE KOHLHAAS: It’s like anything that’s unfamiliar. You learn a little more about it and you get a little more acquainted with it, you talk to other people about it and you — it sort of starts to normalize as an idea.

KATIE CAMPBELL: And even her biggest skeptic has come around.

TODD MARTIN: I would highly recommend to other neighborhoods. In fact, I would love to see Seattle be known throughout the country for these — this rain garden program.

WOMAN: We got to all squeeze in more, don’t we?