The 1939-era dam that blocked the Willow River in the Minnesota town by the same name is on its way out, to be replaced by a series of rock rapids designed to allow fish to swim upstream but also retain the small but popular Lake Stanton reservoir.
The Minnesota Department of Natural Resources is heading the nearly $2 million project with contractors on the job this winter, part of an ongoing statewide and national effort to re-wild river ecosystems whenever possible.
The project is just upstream from where the Willow River flows into the Kettle River. The dam was breached and damaged in a July 2016 mega-rainstorm and ensuing flood that mostly drained the lake. But rather than replace it, the DNR sought to make changes to reopen the river to migratory fish, native mussels and other aquatic creatures that had been blocked for nearly 80 years — including lake sturgeon that are native to the St. Croix-Kettle-Willow River system.
“The rapids are designed for a (stream) velocity that allows sturgeon to pass, and the gaps will be wide enough for them to get through,” said Jason Boyle, state dam safety engineer for the DNR.
In December, contractors temporarily diverted the river channel and dewatered the work area so they could remove the failed concrete dam. In the next phase of construction, expected to last into February, a series of steps and slopes will reshape the riverbed below the small lake. Base rock and large boulders will be placed to create so-called arch rapids that should eventually retain water in Lake Stanton near its previous levels.
The river upstream of the old dam should also make decent habitat for walleyes and other game fish, at least during high flow periods, said Leslie George, DNR area fisheries supervisor in Hinckley.
“It’s absolutely a step in the right direction for fish passage up the Willow River,” George said. “That dam was a total barrier before.”
Residents of the town and people who camp at the campground on the shores of the little lake made it clear they liked the impoundment for recreation and wanted to restore the reservoir, Boyle said. The Willow River Campground is part of the General C.C. Andrews State Forest.
Boyle noted that removing the dam also eliminates the roiling waters at its base that are considered a drowning hazard.
Because of the extensive nature of the construction and heavy equipment needed to perform the work, the adjacent Willow River City Park, now a staging area for construction materials, is closed to visitors. During the final phase of construction in the spring, rock placements will be touched up, a trail will be built along the rapids and trees and grass will be planted. The water level in the Stanton Lake reservoir is expected to refill by late spring as snow melts.
The lake is between Interstate 35 and old Highway 61 and when full is roughly 87 acres in size and about 12 feet deep at its deepest point. Several species of fish are common in the area, including bullhead, bluegill, largemouth bass, northern pike, rock bass, smallmouth bass, walleye, yellow perch and pumpkinseed.
The $1.8 million project is funded by the construction bonding bill passed by the 2017 Minnesota Legislature. The project was delayed several years due to the complexity of retaining both the previous lake level and allowing fish passage, Boyle noted.
In nearby Sandstone, a dam was removed from the Kettle River a few years ago in a move that reopened miles of habitat for sturgeon. Meanwhile, the DNR is currently making plans to remove another dam in the area, the Grindstone Dam in Hinckley on the Grindstone River.
Minnesota has about 1,100 small dams on streams across the state, many built in the early 1900s to create ponds, provide electricity, run sawmills or control flooding — and many of which are now in need of repair or removal.
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January 24, 2021 at 05:19AM
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DNR removing Willow River dam to allow fish passage - TwinCities.com-Pioneer Press
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