With new gates and high water levels year-round, the Coon Rapids Dam could block Asian carp, a consultant says.
A $16 million upgrade could turn the 97-year-old Coon Rapids Dam into an effective barrier against Asian carp migrating up the Mississippi River, a consultant reported Tuesday.
A dam with new gates, a repaired underwater apron and revised operating rules to keep upstream water at summer levels year-round could make the dam 99 to 100 percent effective at stopping the carp from jumping upriver to Minnesota's prime game fish lakes, said Martin Weber, principal water resources engineer for Stanley Consultants.
Weber reported his findings to the Coon Rapids Dam Commission, a panel of public officials and citizens established by the Legislature. The commission is expected to make a recommendation about the future ownership and operation of the dam to the Legislature by March 1.
If legislators approve and fund the improvements this year, the work could be done by 2013, Weber said. Without the improvements and operating changes the dam is 89 percent effective as a fish barrier, he said.
"This is a huge issue for the entire state of Minnesota," said Champlin Mayor Mark Uglem, who serves on the commission and is worried about Asian carp spoiling fishing on northern lakes. He said he hopes funding approval "comes really fast because it has to."
Commission members had been expecting a $20 million to $25 million price tag for dam improvements, Uglem said. "This is the blue-light special of all blue-light specials."
Asian carp grow huge, like to eat and reproduce, and ruin habitat for native fish, Weber said. Asian carp are in the river in great numbers halfway through Iowa. Some have been found as far north as near Hastings.
The carp migrate during floods when high waters carry them over barriers. They can swim up to 25 feet a second and jump 10 feet, Weber said.
The Coon Rapids Dam's main function now is to create a 6-mile pool for recreation. Since 1968, the water level has been lowered in the winter to protect private docks and boat houses from ice damage. Before that time, a constant level was maintained year-round, Weber said.
Water levels would have to stay at summer levels to make the dam an effective fish barrier, Weber said. "By keeping the winter pool higher you reduce the opportunity for fish to swim upstream.''
Weber's firm has a $164,087 contract with Three Rivers Park District, which owns the dam, to study prospects for its future. The park district will be reimbursed for the study from a $500,000 fund set up by legislators.
Laurie Blake 612-673-1711