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State says city won't get storm water credits for Grass Lake project, but project planning continues

This aerial photo depicts what the restored Grass Lake basin would look like. Highway 71 is the major road visible at the far left, and the Highway 71/23 Bypass is the road at an angle immediately adjacent to the basin in the left of the photo. The city of Willmar is no longer participating in the restoration project with Kandiyohi County and other agencies because the city will not receive credit from the state for using Grass Lake to filter pollutants from storm water runoff before the water enters Lak...

WILLMAR -- Construction activities could begin next year on the 1,200-acre Grass Lake restoration project, even though the city of Willmar is no longer a participant.

The city had been working with Kandiyohi County, state agencies and other groups for the past 20 years on an initiative to restore Grass Lake, located adjacent to Willmar on the southeast side of the Highway 71/23 bypass. The shallow Grass Lake basin was drained decades ago by the county and landowners for farmland.

Project supporters have said benefits include wildlife habitat improvement, downstream water quality improvement and storm water runoff management for Willmar, Lake Wakanda and Big Kandiyohi Lake.

Lake Wakanda and downstream waters are listed as impaired waters of the state by the Minnesota Pollution Control Agency. Because of that, a "total maximum daily load'' requirement will be drafted to address that impairment. The requirement has not yet been written, according to sources.

The city had hoped to use Grass Lake to filter storm water from a 3.6-square-mile watershed that currently flows via County Ditch 23A through the basin and into Lake Wakanda and other downstream waters.

The city had received an indication about water quality treatment efficiencies from Grass Lake in an Aug. 28, 2009, report by Barr Engineering. The report said if Grass Lake is restored, the estimated total removal of phosphorus (a pollutant) will be 59 percent.

The study said Lake Wakanda will benefit because nutrients will be reduced, helping Lake Wakanda meet Minnesota's water quality standards.

Earlier this year, the city asked the Minnesota Pollution Control Agency if the city would receive credit from MPCA toward future storm water discharge permit regulations. Among other things, the city asked if MPCA would offer a "regulatory acknowledgement'' as a good faith effort to improve water quality.

Assistant MPCA Commissioner Rebecca Flood responded that the city would not receive credit. The agency said "the science of wetland assimilative capacity for pollutants and the regulations and approaches to storm water management have evolved.''

The agency said it was concerned the project could have "unintended consequences of making things worse for downstream impaired waters.''

MPCA also said the city would not receive credit because Grass Lake is located outside city limits and is not part of the municipal separate storm sewer system for which the city is permitted.

As a result, officials will be directing city resources toward storm water quality projects within the city limits. Those projects include the desire to use the old wastewater treatment plant site to construct a detention pond to treat storm water from Ditch 23A before the water heads for Lake Wakanda.

"If we're being asked to contribute a lot of money to this project, what's the benefit to the city because they always talked in terms of storm water and water quality issues,'' said City Administrator Michael Schmit.

"So we wrote this letter and we specifically asked the MPCA what are our benefits, are we going to get some credit by participating in the project and essentially their response was no because all of this activity is taking place outside Willmar's city limits,'' he said.

"As a practical matter based on the response from MPCA, the city has no incentive to participate,'' said Schmit.

"What we've said is that we chose to spend our money on storm water control and water quality issues within our corporate limits. Hence, the decommissioning project at the old wastewater treatment plant and we'll be looking at some of those recommendations that came from the Storm Water Task Force. That's pretty much where we are today,'' he said.

Planning continues, however, on implementing the project, according to Loren Engelby, drainage and ag inspector for the Kandiyohi County Public Works Department. Engelby is working with Tom Wenzel, senior water resources engineer at the Minnesota Board of Water and Soil Resources, and his technicians, to design specific construction activities and determine costs.

Those activities include ditch rerouting, installation of culverts and structures, and land acquisition. Those costs will be paid with $2.2 million approved by the 2006 Legislature. Engelby said the funds must be encumbered, but do not have to be spent, by the end of 2010.

Engelby hopes to see some activity in the basin area next year.

"I see no reason why we won't see activity there,'' he said.

A big-ticket item will be rerouting Branch 3 that drains a 1.4-square-mile watershed in east Willmar. The ditch currently flows under the bypass and through the basin. The ditch would be rerouted parallel to the bypass to a proposed storm water sediment pretreatment pond at Ditch 23A next to the bypass.

Another project involves construction of a pond to settle out sediments carried by Peach Creek, which drains a 6.8-square-mile watershed generally located east of Willmar, north of County Road 23 and west of Kandiyohi. The creek comes along Highway 12 near Haug Implement and along the bypass until it reaches Branch 3 and Ditch 23A.

The settlement pond would be located just south of County Road 23 and would be built to allow a back hoe to remove sediment before water reaches Grass Lake.

The project's second phase involves constructing a channel south of the basin to handle large flows from Willmar during heavy rain events and installation of pumps in the Ditch 23A sediment pond.

Another project benefit cited by Barr will be a decrease in the flood level "bounce'' at Lake Wakanda because a large percentage of storm water runoff will first be detained in Grass Lake.

Wenzel said Grass Lake is a good project.

"We are banking on the fact that it's going to provide some positive outcomes in terms of the downstream impairments and therefore it will pay for itself in the long run,'' he said.

David Little
David Little covers the Willmar City Council, Willmar Municipal Utilities and other city news.
(320) 235-1150