Watershed district now sees storm water as a liquid asset

That storm water running off the roof, down the street, across the parking lot and into a sewer grate must be stopped, the Minnehaha Creek Watershed District has decided.

After decades of viewing storm water as a problem to pipe away, the district now sees it as a resource that should be put to good use right where it lands.

"The water that falls from the sky and lands on your property -- you own that water, you are responsible for that water," said Eric Evenson, watershed district administrator.

This new direction comes from the quiet governing body that regulates the level and quality of water in Lake Minnetonka, Minnehaha Creek and the Minneapolis Chain of Lakes.

With policymaking and taxing power in 29 cities and townships, including Minneapolis, Edina, Minnetonka and Hopkins, the watershed district, one of the largest in the metro area, is carving out a bigger role in protecting the environment.

This year, 40 years after it was created to end flooding on Minnehaha Creek, the district has turned its focus to water quality, with an ambitious, $86 million, 10-year plan.

Its goal is to clean the water in the district's lakes and streams by relieving them of pollutants swept in by storm water.

To show cities, developers and homeowners how to do this, the watershed district invested $1.5 million in the redevelopment of downtown Mound to make it a model of the latest landscaping and storm water management techniques.

There, every drop of water from a new transit station, condos, townhouses and parking lots will be filtered into the ground or through sand before it reaches Lake Minnetonka, Mike Wyatt, planner for the Watershed district, said.

At the townhouses, underground storm water pipes were replaced by a "dry creek'' ditch that catches runoff and lets it flow along the surface as part of creative landscaping.

"We wanted to use it as an asset -- an aesthetic feature,'' Wyatt said.

At the nearby transit station, rain filters directly into the ground through porous pavement or into a box of sand and finally to a storm water holding pond, where pollutants settle out before the water reaches Lake Minnetonka.

The result is cleaner water going into the lake, Wyatt said. "Before, all that runoff would have gone directly into a storm sewer which outletted directly into the lake."

Thinking of storm water as an asset to be captured and used for creative landscaping and watering is a significant shift in Minnesota, where water is considered almost a liability and "storm sewers are all sized to get the water out of town,'' said Mike Panzer, vice president of Wenck Associates, the consulting engineer for the district.

The district arrived at this strategy after several years of discussion about what it should be doing for the next decade and beyond, said board chair Jim Calkins, a horticultural scientist at the University of Minnesota.

"We have done a lot of research and we have come to the conclusion that this is the best way to preserve the resource that we have,'' he said.

The district has succeeded in slowing down storm water drainage to stop flooding. The next challenge is reducing its volume.

If that is accomplished, the new plan "will lead to true improvement in the water bodies within the district,'' Calkins said.

The strategies can be costly.

The district plans to use its $86 million capital budget to restore wetlands that are natural filters for storm water, to rebuild stream banks, and to buy key parcels of land near lakes and streams to keep them in their natural state as water cleaners.

It began moving in that direction two years ago when it spent $800,000 to pay for easements to protect wetlands on the 56-acre Big Island in Lake Minnetonka, plus another $750,000 to buy 36 acres near Painter Creek in Minnetrista.

After tearing down the house on the Minnetrista site, the district plans to subdivide the land into three lots and sell them with an easement requiring that 30 acres remain in a natural state to filter water going into the creek. The creek empties into Lake Minnetonka in Jennings Bay, which has some of the worst water quality on the lake, Wyatt said.

The watershed district's new direction will show up next in updated community development guidelines. Developers and property owners who want to make major property changes will feel the new rules first, officials say.

Education campaigns will be aimed at homeowners to help them learn to manage their own storm water just as they learned to recycle their own yard waste, Wyatt said.

On the heels of a summer marked by drought, sprinkling bans and water shortages, it's easy to see the benefits in capturing the water, Wyatt said. "This stuff comes from the sky and it comes for free. You shouldn't have to take water from municipal water supply and use that to water your trees.''

It may be helpful for homeowners to think of storm water as they think of snow, Wyatt said. "You have to shovel your sidewalk when it snows, and you don't take your snow and throw it over on your neighbor's side.''

Minneapolis is already offering a credit on the annual storm sewer fee for homeowners who put in rain gardens or use porous pavers or rain barrels to hold the water on their property, Wyatt said.

"I see that as something that will eventually permeate through the metro area and likely the state, especially in the urban areas,'' Wyatt said.

Laurie Blake • 612-673-1711