The Coon Rapids Dam Commission recommended Tuesday that the state spend $17 million to upgrade the 100-year-old dam to keep unwanted fish from migrating up the Mississippi River into popular northern Minnesota lakes.

The recommendation, backed by the state Department of Natural Resources (DNR), urges legislators to make improvements as soon as possible using state bonds, money provided by the Legacy Amendment or other funds.

"This is the best option we have at the moment," said Luke Skinner, supervisor of the DNR's invasive species program. "We don't have the luxury of time."

A major concern is a feared influx of high-jumping Asian carp, reducing habitat for game fish and creating a hazard to boaters and water skiers.

"Limiting the migration of invasive fish species is a statewide issue impacting the $4 billion-plus statewide annual fishing, water recreation and tourism industries," the recommendation says.

Gov. Mark Dayton has included $16 million for dam repairs in his proposed $1 billion bonding bill. Legislators also have introduced several bills to make money available for repairs. However, funding is uncertain with the state facing a $6 billion budget deficit.

The dam, which straddles the Mississippi between Hennepin and Anoka counties, is used to back up the river for swimming and boating. It is owned and operated by Three Rivers Park District. Its continuing need for expensive repairs had raised questions about its future.

Legislators created the dam commission last year -- filling it with local, state and federal officials -- to make a recommendation on the dam's future by March 1.

In a recently completed report to the commission and the DNR, Stanley Consultants said that $17 million in repairs, including a new spillway gate, could keep the dam functioning for 50 years. If water levels behind a repaired dam were kept high year-round, it could be 99 percent effective as a barrier to the northward migration of Asian carp and other unwanted fish on the Mississippi, Stanley said.

Asian carp are already established in the river in Iowa and could arrive in Minnesota in two to 10 years, the DNR has said. Dam improvements would protect lakes and streams in about a quarter of the state, including Mille Lacs, Gull and Leech lakes, the commission said.

DNR regional manager Dale Homuth, who served on the commission, said the dam improvements could be completed in three years if the state OKs the funds this year.

Improvements would not make the dam a foolproof barrier. Using historic water records, the consultants found 36 days in the past 80 years on which carp would have been able to jump past the dam, Homuth said.

The dam at St. Anthony Falls and the Ford dam would be better fish barriers, Homuth said. The U.S. Army Corps of Engineers operates locks on those dams for boat and barge navigation. Getting federal permission to convert either to fish barriers would require study and legislation.

Improving the Coon Rapids dam would have recreational benefits, as well, Homuth said. "There are 400 people who live on this pool who really want it to stay."

Three Rivers, which no longer wants to own the dam, believes that the DNR should take it over because the dam's future "is as a fish barrier,'' said Boe Carlson, associate superintendent for the park district.

The DNR resists, saying that it "is not in a good position to operate dams that require this much work," Homuth said. "We would have to hire someone to do it."

Laurie Blake • 612-673-1711