Dennis Anderson: Two years after receiving $12 million to keep Mississippi River carp in check, Minnesota DNR says deterrent won't be ready until 2029

MINNEAPOLIS — If you live, fish or boat on Lake Pepin, the St. Croix or Minnesota rivers, and you worry that someday thousands of silver carp might leap from those waters, ruining your fun, property values or both, nothing you’re about to read will give you comfort.

That’s because the Department of Natural Resources — though handed $12 million two years ago to install an invasive carp deterrent at Lock and Dam No. 5 on the Mississippi River — is balking again at getting that work done.

In 2023, the DNR’s website claimed the agency “has been working to slow the spread of invasive carp since the early 2000s. A renewed effort began in 2011, (when) a collaboration of state and federal agencies, conservation groups and university researchers developed the Minnesota Invasive Carp Action Plan.”

It might have been more accurate to call it an Invasive Carp Inaction Plan. Silver carp and their buddies — bigheads and grass carp — had been swimming upstream at an increasing rate, topped off by the 30 silvers caught near Winona on March 20, 2023.

That was the highest number of silver carp ever caught so far upstream in the Mississippi.

For the record, these fish can grow to 40 pounds and, while performing their missile-like aerobatics, have been known to whack boaters in the noggin.

Pressed again that year to support installation of a deterrent at Lock and Dam No. 5 to help prevent invasive carp from establishing breeding populations in Lake Pepin and the Minnesota and St. Croix rivers, the DNR opted instead to form a committee to talk things over — a $75,000 gabfest the agency peddled as a “deliberative decision-making process.”

The result? The DNR determined a Lock and Dam No. 5 carp deterrent could wait until 2028.

“Absolutely not,” University of Minnesota professor and invasive carp expert Peter Sorensen told me at the time. “If you look at the time frame in which silver carp have moved upstream in the Mississippi, you can reasonably estimate they will be past Lock and Dam No. 5 in five years and perhaps less. My view is we should start installation as soon as possible.”

Doing nothing, Sorensen said, would be “environmentally irresponsible.”

The conservation group Friends of the Mississippi River also wanted a deterrent installed as quickly as possible, as did MN-FISH, a statewide angler group. Others favoring a deterrent included the National Parks Conservation Association and Lake Pepin Legacy Alliance.

If the DNR hadn’t lobbied legislators against funding for a carp deterrent at Lock and Dam No. 5, the project might have gotten an appropriation in 2023 or 2024. When that didn’t happen, the Lessard-Sams Outdoor Heritage Council ponied up $12 million for the barrier on March 26, 2024.

Appearing before the council that day, DNR director of Ecological and Water Resources Katie Smith said, “There are many engineering, evaluation and research pieces that must first be explored,” before installing a deterrent, adding that for an impediment to be effective it must be combined with carp-tracking and removal strategies.

At the same meeting, U.S. Army Corps of Engineers St. Paul district project manager Michelle Prosser was more upbeat. She told the council the barrier could be installed within “one or two years.”

So, two years later, where are we?

Still talking. And balking.

Begin with a Feb. 2 letter from Smith to LSOHC chairman David Hartwell and the council’s recently appointed executive director, Kristina Smitten. In the letter, Smith notes that only two other carp deterrents are in place nationwide, and she calls them, “experimental.”

“As a reminder,” Smith said, “the two existing deterrents prevent about 50 percent of invasive carp from passing upstream through navigation locks,” adding that — and this doubtless was a key reason for Smith’s letter — “the DNR now has additional information about costs and timeline for the deterrent.”

Smith goes on to say that the $12 million the LSOHC gave the DNR for the barrier won’t be enough. And that annual operation of the barrier and carp tracking and removal will run north of $200,000.

“We want to draw your attention to this information,” Smith writes, “as this project involves a significant investment of resources for Minnesota, particularly given the limited efficacy of deterrents. We recommend that the DNR and Interagency Workgroup partners have a discussion with LSOHC and the copied Legislative Chairs to provide further information and answer any questions.”

In an interview last week, Hartwell told me Smith would appear before the LSOHC in May. If, during that meeting, Smith reports that a deterrent will only be 40% or 50% effective, Hartwell said, he will ask, “Why are we doing this?”

Two points.

Hartwell knew two years ago when he voted with the rest of the LSOHC to appropriate the $12 million for a deterrent that it wouldn’t block all invasive carp from swimming upstream.

“We know doing nothing is going to lead to carp getting upstream at some point,” Hartwell said at the time. “So it’s kind of a terrible choice if you want to know the truth, but at least we are seeing an interest in doing something at this point.”

Smith also said in an addendum to her letter that a deterrent at Lock and Dam No. 5 won’t be installed until — wait for it — 2029.

“The way the DNR is presenting the effectiveness of a carp barrier is overly simplistic,” Sorensen said on Wednesday, March 4. “They’re taking a narrow, defeatist perspective and it bothers me.

“We don’t know how many adult silver carp, as an example, it takes to form a breeding population, but we know it’s quite a few,” he added. “If we do nothing, it’s a given that a breeding population will be achieved in Lake Pepin and the St. Croix and Minnesota rivers at some point. If we install a barrier, combined with a trapping and removal system, that population might someday be achieved, but it would be at a much later date, if ever. Meantime, we might figure out new and better ways to stop these fish.”

Sorensen noted that everyone involved with invasive carp and their widespread infestations of U.S. rivers has known that deterrents aren’t a sure thing, and that to maximize their effectiveness they have to be combined with trap and removal.

A similar impediment has been part of a successful Illinois strategy that has kept invasive carp out of the Great Lakes for the past decade, he said, and given the value Minnesotans place on their lakes, rivers and fish, it’s worth trying.

“There’s risk with a deterrent, combined with trapping and removal of carp,’’ Sorensen said. “But the risk of doing nothing is far greater.”