DNR OKs plans to fix dam, lake at state park

The Minnesota Department of Natural Resources is recommending the dam at the Blue Mounds State Park be replaced and the pond restored.
According to the construction timeline, however, the Lower Mound Lake won’t be reestablished and open to the public until 2018, more than four years after flooding destroyed the concrete structure.
The recommendation to replace the dam came from state DNR officials who met with County Commissioners on Tuesday, Nov. 17.
They shared the department’s project timeline and said a final decision on the plan is scheduled for next month.
Kathy Dummer, DNR regional director of parks and trails, provided the project timeline leading to August 2018 completion. The timeline includes steps DNR officials have taken and will take with various state and federal agencies in the flood damage assessment and to study possible solutions.
“A lot of this work was still going on up until last week,” she said.
Conclusions so far support the dam’s repair to allow the 20-acre recreational Lower Mound Lake to fill with water again.
Preliminary Federal Emergency Management Agency cost estimates put the plan at $2 million.
“We are all thinking this is really conservative,” Dummer said.
An exact cost won’t be known until the construction bids are awarded in June 2017.
If the DNR plan is approved, the environmental review process will begin in 2016.
Because of the endangered Topeka shiner minnow and the historic significance of the dam (built under the Work Projects Administration in 1937), there is added federal interest in the project.
Reviews may take four to 12 months (from May 2016 to May 2017) to complete.
Regional officials speculate the various environmental studies will take almost a year.
“Because of the complexity, we are erring on the unconservative side,” Dummer said.
The review will examine the federal requirements under the National Environmental Protection Act, Clean Water Act, Endangered Species Act and Historic Preservation Act.
At the state level, the review will consider requirements from the Minnesota Environmental Protection Act.
Each element of the review can take place concurrently to complete the final design, the timeline indicated.
Dummer said this summer’s field study found two additional state endangered or threatened species at the park, the plains topminnow and the pond mussel.
Field studies also determined the park’s upper dam near the campground is structurally sound.
“There are a few stones that were blown out and some concrete but nothing that compromised the integrity of the structure,” Dummer said.
Work to replace the missing elements on the upper dam is cosmetic and will be completed, she said.
Since Lower Mound Lake dam was blown out during June 2014 flooding, Rock County Commissioners were concerned  they may need to replace the bridge on County Road 8 east of the former dam.
Dummer shared a letter received from the state’s dam safety engineer stating the current bridge is adequate to handle a two-year flood event up to a 500-year event as determined by the DNR’s engineering software models.
“The dam has been determined to have no effect on the County 8 bridge,” stated the report by Jason Boyle.
“The dam does not affect the bridge hydrologic and hydraulics during flood events as the dam provides little flood storage.”
The June 2014 weather event was similar to a local 100- to 200-year event, Dummer added.
At the Nov. 17 meeting DNR regional director Dennis Frederickson said the local concern and support for repairing the park’s dam and reestablishing a water recreation location in Rock County was key in getting the attention and the monetary support of state officials.
“That is one of the questions we get in St. Paul, in our state agency and also at our state legislature — ‘Do local people care about it? Is the city involved? Is the county involved? Is there local support?’” Frederickson said.
“If there is local support, it is a lot easier to get projects accomplished.”