by Peter Bodley
The six-mile recreational pool above the Coon Rapids Dam will be raised to its normal summer level beginning on or about Feb. 20.
That does not normally happen until the beginning of May.
But the Three Rivers Park District, which owns and operates the dam, is taking the action this month at the request of the Minnesota Department of Natural Resources (DNR).
According to Jason Boyle, state dam safety engineer, the action was requested because Asian carp pose a significant threat to aquatic habitat in the Mississippi River and raising the water level in the pool behind the Coon Rapids Dam this winter will make the dam a more effective fish barrier.
“Property owners along the pool should immediately begin to remove any docks and boat lifts from their shoreline that could be damaged by the higher water levels,” Boyle said.
“Winter recreationists should be on alert, because ice conditions in the pool will be unpredictable for the rest of the winter.”
The DNR recently met with representatives of the park district, the U.S. Army Corps of Engineers, the U.S. Geological Survey, the National Weather Service and several local residents and community representatives, to discuss how to raise the pool in a safe manner to minimize damage to the shoreline and the danger to wintertime recreationists.
According to Boyle, the DNR was advised to raise the pool slowly (no more than six inches per day) and to do it when open water is visible in the center of most of the pool.
The decision to start the pool raising process on or about Feb. 20 was made after DNR and park district staff monitored ice conditions on the reservoir, Boyle said.
“DNR hydrologists do not believe this change in dam operations will affect overall peak flood levels along the pool,” he said.
“The Coon Rapids Dam pool does not contain enough storage to lessen flood levels. The water level of the pool when a flood starts does not make any difference in the severity of flooding.”
Currently, the pool is about three feel below normal summer levels, Boyle said.
Meanwhile, the process in the project to reconstruct the Coon Rapids Dam to make it a more effective Asian carp barrier with $16 million in state bonding approved by the 2011 Minnesota Legislature is moving forward.
According to Boyle, a consulting engineering firm has been chosen by the DNR to provide engineering and design services as well as administration and construction management for the project.
Right now, negotiations are under way between the DNR and the engineering firm on a contract, which will have to be approved by the Minnesota Department of Administration before it goes into effect, Boyle said.
Boyle hopes the approved contract will be in place and the engineering firm ready to start work on the project design at the end of this month, he said.
Under the DNR’s timeline for the project, plans are to go out for construction bids next fall with reconstruction to start in the spring of 2013 and completion in 2014, Boyle said.
Still to be determined is whether the recreational pool will be kept at its summer level during construction, he said.
“There would be a great benefit in keeping the pool at it summer level during construction as a carp barrier, but it will cost more,” Boyle said.
“This is still under consideration.”
But the DNR plans to keep the pool level at or near the normal summer pool level all year long in the future, according to Boyle.
It has been recently reported that DNA from the invasive silver carp has been found above the Coon Rapids Dam.
The Three Rivers Park District and the DNR last month signed a joint powers agreement which paves the way for the dam reconstruction project.
The DNR will be replacing the present rubber gate system with hydraulic or pneumatic gates that pass the water over the top as well as making other badly needed repairs.
These includes repairing a scour hole found in the concrete apron of the dam during a routine inspection in late 2010.
The Coon Rapids Dam was built in 1913 by Northern States Power (NSP) Co. to generate hydroelectric power.
When power generation stopped in the 1960s, NSP donated the dam and surrounding land on both sides of the river to the park district.
Anoka County now owns all the park property on the Anoka County side of the dam.
To date, the future ownership of the dam has not been addressed by the Legislature.
The Three Rivers Parks District has made it clear that it no longer wants to own and operate the dam and the DNR should be responsible for the dam.
The Anoka County Board has gone on record in support of the Three Rivers Park District position.
Peter Bodley is at [email protected]