Experts come together for Lake Altoona brainstorm session

Aug. 25—EAU CLAIRE — Efforts are underway to extend the life of Lake Altoona.

Representatives from the UW-Eau Claire, the Wisconsin Department of Natural Resources, Eau Claire County, Army Corps of Engineers and Lake Altoona District members met to brainstorm strategies to solve the sedimentation problems plaguing Eau Claire's lakes.

Without intervention, Lake Altoona is slated to fill in completely with sediment by 2050.

"I'm very grateful for the amount of brain power we have in this room today," Lake Altoona District Chair Michele Skinner said.

A large portion of the discussion surrounded the historical nature of the Eau Claire River Watershed and what factors have led to the rapid sedimentation buildup in Lake Altoona.

The man-made lake sits at the end of the Eau Claire River Watershed, collecting all of the sand and silt materials eroding along the river.

"This isn't something that is just (now) happening, this is something that has been going on for a long time," Dr. Douglas Faulkner, professor of Geography and Anthropology at UW-Eau Claire, said.

Major changes in climate patterns and human impacts can attribute to the rate of sedimentation flowing down the Eau Claire River. Sedimentation rates can be increased by major flooding events in particular.

In order to start planning any lake-saving projects, more data needs to be collected from the lake and river waters. Terry Zien said there is potential to utilize sediment transport models, however, there are too many data gaps before they could consider this option.

Zien works in programming and project management within the St. Paul district of the Army Corps of Engineers.

He expressed hope in finding viable mitigation strategies for his program to potentially fund.

The Lake District has already taken the initiative to fill some of these data gaps. A collaboration with the Lake Eau Claire District has allowed the groups to use bathymetric mapping equipment to gain an understanding of how much and where sedimentation is building up on the lake floor.

The districts were also recently awarded American Rescue Plan funds to conduct water quality tests and purchase sonar and drone equipment.

Some potential areas for future data collection include charachterizing the sediment, seismic profiling of the river basin, monitoring the river sediment flow and mapping the river bed.

"What we're trying to do as an outcome of today is to create action steps," Lauran Larson, member of the Lake Altoona District said. "What are tangible things that we can measure?"

Rod Zika, a retired professor from the University of Miami Rosenstiel and scientific advisor for the lakes, presented the group with some potential mitigation measures. One of these measures included changing the dredging method from hydraulic to mechanical dredging.

Although hydraulic dredging provides less disturbance to the environment of the lake bed, the cost is just not feasible for the districts.

Skinner told the Leader-Telegram the districts are still paying off the hydraulic dredging of the lake they did the first time around and are unable to afford to do it regularly.

Mechanical dredging was done in 2016, when the Lake Altoona dam needed maintenance. Lowered water levels allowed heavy machinery to travel out onto the lake bed and excavate significant amounts of sediment.

A sand trap has also been dug to help slow down the sedimentation by catching sediment before it gets to the lake. However, this process is also costly and does not provide long term relief.

The Lake District board members will meet for their regular annual meeting to discuss these strategies and more in late September.