Governor Mark Dayton put his pen to work in the fight to keep Asian carp out of Minnesota waters. On Sept. 12, he documented an action plan to keep the fish at bay.
The plan gives the state's executive agencies authority to take action in seven ways. Among them is one that hits close to home here in Hastings: evaluating and, if feasible, installing a bubble or sound barrier at the mouth of the St. Croix River in Prescott to slow carp migration.
The Minnesota Department of Natural Resources is looking into the bubble barrier for the St. Croix and at the same time is searching for project funding, said Tim Schlagenhaft, Mississippi River planner for the DNR. If the studies show the barrier is feasible, they want to be able to move forward with it as quickly as possible, he said.
So far, there's not much data to tell the DNR what to expect.
"There isn't a lot of information," Schlagenhaft said. "There's never been a barrier like this that's been installed on a river the size of the Mississippi or the St. Croix."
What he does know is that to install and operate the barrier for four years would cost about $10 million. There's no set location for the barrier. Potential regions have been identified - at the mouth of the St. Croix River, at Lock and Dam No. 2 in Hastings or Lock and Dam No. 1 - but nothing more specific has been determined. And it's not entirely fish-proof.
"It won't prevent all fish from passing. So Asian carp would still get past the barrier," he said.
Only a solid barrier would be able to stop the fish. The point of the bubble barrier, he explained, would be to slow the advance and give the DNR and other agencies a little more time to develop other tools that would have a more permanent effect.
Cost-efficiency is one of the aspects the DNR is trying to evaluate, Schlagenhaft said. Some will argue a temporary barrier that doesn't stop all Asian carp isn't worth $10 million, but officials have sent the message that something has to be done.
"There's no easy answer to this problem," Schlagenhaft said.
Of course, a barrier that deters Asian carp will also affect other types of fish.
"We also are concerned about the effects on native fish," he noted, "because native fish need to be able to move between the river systems."
The studies under way will help determine how serious the effect could be. Another question is what impact the barrier would have on recreational angling in the area. Schlagenhaft said he's guessing that the opportunity for fishing above and below the barrier wouldn't change, and even though anglers could fish right around the area of the barrier, they probably wouldn't want to. It's not expected to have any impact on boaters passing through.
"According to the contractors, you'd still be able to boat across," Schlagenhaft said.
The DNR needs to conduct an environmental assessment yet, which it hopes to do jointly with the Wisconsin DNR. That process would help identify more accurately what local impacts there could be. Schlagenhaft said the environmental assessment may take about six months.
The bubble barrier isn't the only method being considered. The best way to keep Asian carp out of Minnesota rivers is through multiple approaches.
"We're not just looking at one thing," Schlagenhaft said. "We're looking at a number of things in combination."
One tool that will be important is restoring native habitat to the area so native species are better able to compete with the larger fish. Evidence for this is seen by watching native fish interact with common carp already in the rivers.
"Where we have good habitat, common carp are less of a problem," Schlagenhaft said.
They're also looking into using bio bullets - food pellets with a coating that reacts with the specific enzymes in the Asian carp's digestive tract and is toxic to that fish. Species of fish that don't have that enzyme would be able to eat the pellets without being affected.
When the action plan is developed, it will likely include several options for managing the spread of Asian carp.