Urban
Conservation
protecting water quality in your neighborhood
By Theresa Bjork
A statewide team of urban conservationists are working with cities, developers and local residents to protect Iowa's lakes, rivers and streams.
Jennifer Welch says she can’t drive by a paved parking lot without thinking about a missed opportunity to help protect Iowa’s water quality.
Welch, an urban conservationist in Polk County, says most Iowans don’t realize that rainfall runoff from parking lots washes directly into nearby rivers and streams via the storm sewer, without being treated to remove any pollutants.
“We often tell the urban people that they live on waterfront property if they have a storm drain in front of their house,” says Welch, who works for the Polk County Soil and Water Conservation District in central Iowa.
The Iowa Department of Agriculture and Land Stewardship has launched an urban conservation program to help educate landowners, businesses, developers and cities about opportunities to improve water quality in urban environments.
Welch and four other urban conservationists are working across the state to provide information and technical assistance for private and public water-quality projects.
Welch says parking lots and streets can be constructed to help filter storm water runoff before it reaches rivers and streams. Urban and suburban residents also can make water-quality improvements in their own backyards.
“Managing the runoff from their property is something every Iowan, both rural and urban, can do to help protect water quality in the state and prevent erosion,” says Iowa Secretary of Agriculture Bill Northey.
Northey says that In the past, urban storm water management efforts were focused on preventing flooding, without consideration for water quality, Northey says.
“Rather than just moving the rainwater that lands in our urban areas quickly to our rivers, lakes and streams, we are working on installing practices that allow water to filter through the soil rather than just running into the stream,” he explains.
Wayne Petersen, an urban conservationist with more than 11 years of experience at the U.S. Natural Resources Conservation Service, is now overseeing the Iowa Department of Agriculture’s urban conservation program.
Petersen says the urban conservationists are working with cities and developers to find ways to manage water runoff from small rain storms, not just from the heavy rains that flood streets.
Small rain storms account for the majority of the state’s precipitation, Petersen notes. About 84 percent of rain events in Iowa total less than one-half inch.
“That’s why it’s so important that we manage those smaller rains through (storm water) filtration,” Petersen says. “That’s when we will get water quality and stabilized stream flows.”
One successful example of a storm-water filtration project is at Arnolds Park along West Okoboji Lake, Petersen says.
Three years ago, the Arnolds Park amusement park paved its four-acre parking lot and installed garden-like storm-water filters, called bioretention cells.
Before the paving project, water runoff from the Arnolds Park parking lot washed into the storm sewer, which dumped a cloudy plume of dirty water directly into the lake.
To control this runoff, developers created a green space of topsoil and native plants along the perimeter of the parking lot.
Now, when rain water flows into the green space, the water filters through the soil. Beneficial soil microbes break down any pollutants, including grease, oils and other “car droppings,” before the water reaches the lake, Petersen says.
“The goal is to capture runoff, and within 12 to 48 hours..., the water moves through surrounding soil and becomes part of ground water flow, which is what would have historically happened,” Petersen explains.
A Minnesota study found that bioretention cells can filter 80 to 90 percent of the pollutants from storm water before it hits a lake or river, Welch notes.
Welch says the state urban conservationists are working with city officials, developers and government agencies to install similar water-quality projects on the street level.
On new street projects, cities can install bioretention cells wherever there is a sewer drain to help treat and filter water runoff, Welch explains.
Some cities and businesses are also installing porous asphalt in their parking lots. The material, which resembles a black rice crispie bar, allows water to move through the asphalt and filter into the soil.
Petersen and Welch admit that it sometimes takes convincing to encourage people to rethink how their communities manage storm water runoff, especially if there is extra cost involved.
However, Petersen says many Iowa communities want to become more “green” by adopting conservation practices that benefit soil and water quality.
“I’m convinced that this green movement is a genie that’s not going back in the bottle. It’s going to continue to move forward,” Petersen says.