Moose Lake Star Gazette - Serving Carlton and Pine Counties Since 1895

By Natascha Watercott and Shawn Jansen
Moose Lake Star-Gazette 

Dam options reviewed at presentation

 

December 14, 2017

Shawn Jansen

Jason Boyle, DNR dam safety engineer, presents the options for the Willow River dam in a public meeting last Wednesday at the school auditorium.

On the evening of December 6, well over 100 Willow River area residents and city, county and state government officials settled in at the school auditorium for a long-awaited presentation concerning the fate of the Willow River dam. The dam failed in the summer of 2016 due to flooding. The goal of the event, sponsored by the city of Willow River, Pine County and the Minnesota Department of Natural Resources (DNR), was to inform the community about three main options proposed for the dam and gather input from residents to help make a decision.

Mike Peloquin, regional manager for the Ecological and Water Resources division of the Minnesota DNR, started off the evening with an introduction about the purpose and importance of the presentation. "We know that there's frustration with the time that has elapsed since it [the dam] failed in 2016, but we're ready; we're prepared," said Peloquin.

Earlier this year, Minnesota Sen. Tony Lourey (DFL) District 11 had met with the Willow River City Council and announced he had worked with the DNR to put together a $4.4 million appropriation for public dams and emergency services. This money is being divided among seven projects throughout the state, Willow River being one of them. The dam on the Grindstone River in Hinckley is another.

"We have funding now in place to do a multitude of different options depending on what we can come to consensus on, and we want to start that design work so that we can start construction," said Peloquin. He added that the DNR hopes to start working on the dam by next summer at the earliest if everything goes as planned, but that construction would likely extend into the fall.

Jason Boyle, DNR dam safety engineer, continued the presentation, explaining that the DNR owns the dam, but the city of Willow River owns the property. He provided a brief overview of each of the three options for the dam:

1) Replace the dam.

2) Install a series of rock arch rapids.

3) Remove the dam entirely and restore the river to pre-dam conditions.

Replace the dam

Boyle began with the dam replacement concept. "We know it [the dam] has a spillway that's too small to handle big flooding events, so if the dam is replaced, we know that it can't be exactly like it was," said Boyle. He explained that one option would be to extend the current spillway or to potentially use a different type of spillway. Regardless, the new dam would have to meet current dam safety standards.

The current dam was originally built in 1940, and there are several safety concerns that need to be addressed, the main one being that the dam has to have improved capacity to pass a flood without overtopping.

The other safety concern involves the hydraulic rolling effect on the downstream side of the dam which results in a circular, fast-moving current. Boyle stated there have been several documented deaths because of this effect.

Boyle stated they would also like to find a way to incorporate fish passage into the design, though he noted "it's not a great site for incorporating fish passage; that would come at an extra cost." Boat launching and shore fishing would continue, and riparian owner access would be similar to what it was before the dam failure, as would city park access.

Replacing the dam has the highest cost of the three options, coming in at an estimated $2 million. Boyle explained this cost estimate is the best they can do right now since they don't have any detailed designs yet; they are basing it off of similar projects that have been completed. The dam will also have to be maintained going into the future, which will mean ongoing costs.

Install rock arch rapids

The second option is the installation of rock arch rapids, essentially a series of small pools or weirs enclosed by large rocks. He showed the audience an example based on a similar project, explaining that each pool holds back up to a foot of water. The water drops six inches to a foot, flows into the next pool and drops again. The higher the pool, the longer the series of rock weirs needed to drop the water level. This stepping down design would eliminate the safety hazard of the hydraulic rolling.

The rock arch rapids would provide white-water recreational opportunities as well as a great habitat for fish. Depending on the water level chosen, there could be full to partial riparian access, and they could incorporate city park access to the rapids. The cost for this option is still substantial, noted Boyle, who estimated a total cost ranging from $800,000-1,400,000. The rapids would require very little maintenance though.

This option has been used successfully dozens of times around the state, according to the DNR staff on hand.

Both the dam replacement and the rock rapids result in eventual sediment accumulation in the reservoir.

Restore the river

The third option is river restoration, which is essentially the removal of all the remnants of the dam and restoring the river to what was there pre-1940. The water would be restored to a free-flowing stream and the floodplain would be available for flood events. This option would have full fish passage and improved water quality and biodiversity.

Water would be further away from properties than it is now. There could be riparian access and shore fishing possible, although dealing with the muck of sediment accumulation would be an issue for those property owners. City park access will also be available. This option requires no maintenance and is the safest and least costly option at $400,000-800,000.

Homeowners of properties bordering the reservoir fear lowered property values due to the drop in water level and uncertainty of the dam project, according to realtor and former mayor Tom Jensen. Mayor Brent Switzer said there are eight properties on the reservoir currently.

After the presentation, residents were encouraged to visit information booths set up for each of the three options. Each booth had two specialists available to answer questions and give more detailed information as well as collect public comment. Surveys were distributed for collecting comments as well.

Resident Rose Mielke said, "Build the dam back."

Jensen thought the rock weirs option was a win-win if the water level of the pool was restored fully.

Others also spoke in favor of the rock weir option only if the pool was restored to the level held by the dam. One resident claimed a partial level of water in the pool would encourage wild rice to take over the reservoir area, which grows in one corner. Switzer wondered if property owners could be compensated if a shallower pool with rock weirs or the river restoration path were selected.

One gentleman was in favor of returning the river to its natural state but rerouting it to the Kettle River east of County Highway 61.

After gathering public input, the DNR will meet with the city, probably in January, to discuss the results of the resident survey and comments collected after the presentation. Peloquin stated they want to hear what residents value and how they will be impacted. The DNR will be looking at how the project will affect the lake level, city park, land owners around the dam's pool, safety, cost, infrastructure, recreation, ecology and history.

 

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