Lutsen's Poplar River gets big grant for sediment solution

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The sometimes silty Poplar River that runs into Lake Superior at Lutsen will get a big grant aimed at reducing sediment runoff into the Great Lakes.

The North Shore stream will get $687,034 from the Great Lakes Commission and the U.S. Department of Agriculture’s Natural Resources Conservation Service.

The money will go to the Cook County Soil and Water Conservation District.

One of the North Shore’s most visible, scenic streams, the Poplar has been officially designated as an “impaired” river by the Minnesota Pollution Control Agency based on federal Clean Water Act standards for sediment.

Cindy Gentz, water plan manager for Cook County, said four separate projects will combine to slow runoff down the developed hillside at the Lutsen Mountains ski hills to keep rain and snowmelt from carrying sediment into the river. The largest project will divert water out of a ski-hill gulley at Caribou Highlands and carry it down the hill in a pipe to be released without causing erosion.

Other projects will plant trees to reduce runoff and improve an existing stormwater management system.

It’s hoped the efforts will reduce sediment by about 285 tons per year, Gentz said. That’s in addition to work done in recent years in and near the ski hill where slopes of clay were slumping into the lake.

Resort developments along the river also have used rain gardens, stormwater retention ponds and rock-lined channels to slow runoff and keep sediment out of the river and Lake Superior.

“Our goal is to have the river delisted in five or 10 years,” Gentz said.

The upper Poplar, which runs through mostly undeveloped forests, remains pristine. But in the lower river — as it runs down the steep North Shore hill, along a ski area, golf course, parking lots and townhomes — phosphorus levels double and sedimentation increases sixfold, a 2003 Pollution Control Agency report indicated.

The number of juvenile trout in the river, possibly an indicator of water quality, also declined from 1989 to 2003. The Poplar River also had the highest mercury levels on the North Shore, possibly because mercury bonds to the excess sediment.

Although the Poplar wasn’t listed as impaired until 2004, experts say the problem may be decades old, with heavy sedimentation occurring probably even before development occurred. The river probably has become muddier as tree cover and land use has changed on the North Shore hills, from early logging a century ago to clearing ground for recent resorts.

The Poplar grant is part of $20 million in new money for projects expected to keep a combined 24,000 tons of silt out of the Great Lakes each year.

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