Help prevent the spread of aquatic invasive species while fishing and boating this season

Last weekend, Minnesota’s 2020 fishing season opened with a bang. There was snow up north, only a few fish caught in the St. Croix River, and no cameo appearances from Minnesota Governor Tim Walz. None-the-less, record numbers of Minnesotans purchased fishing licenses last week and set sail in search of walleye, pike, and lake trout for Mother’s Day dinner.


Fun fact: Did you know that a 1989 Minnesota State Law allows mothers to fish without a license during the Fishing Opener weekend? If you don’t believe me, read it for yourself in Minnesota State Statute 97A.445 subd.4, “Any mother who is a resident of Minnesota may take fish by angling without a license during the Saturday and Sunday of the angling season that coincides with Mother’s Day.”

And so, despite frigid winds, shuttered stores, and a raging global pandemic, Minnesotans continue to love their 10,000+ lakes and rivers, and local and state officials continue working to protect these beloved waterways from aquatic invasive species (AIS).

Aquatic invasives are nonnative plants and animals that disrupt aquatic food webs and cause environmental and economic damage. Existing AIS in Washington County include Eurasian watermilfoil, curly-leaf pondweed, zebra mussels, and flowering rush. Other AIS on the horizon that have not yet reached our area include starry stonewort, a macro algae discovered in Minnesota in 2015 that has infested 14 lakes, and spiny waterflea, a tiny animal found in several lakes up north that has been shown to dramatically impact fish populations.

During a recent meeting of the Washington County Water Consortium, MN DNR’s Tina Fitzgerald spoke about the risks of AIS and some of the statewide efforts underway to prevent their spread. “Many people think that the majority of our lakes are already infested with AIS,” said Fitzgerald. “But in reality, only 8% of Minnesota water bodies are infested and only 3% have zebra mussels.”


Watercraft inspections are one of the DNR’s key prevention strategies in the battle to stop AIS. Each year, the state certifies approximately 100 DNR inspectors and 1,000 local inspectors to check boats moving in and out of the water. DNR inspectors typically staff high-use infested waters, while local inspectors cover lower use and non-infested lakes and rivers. Last year, Minnesota led the nation in AIS prevention efforts, conducting 500,000 inspections during the fishing and boating season.

In Washington County, the Washington Conservation District (WCD) conducts watercraft inspections at 12 public boat launches in partnership with the county, watershed districts, and lake associations, and Comfort Lake – Forest Lake Watershed District coordinates inspections on Forest, Bone and southern Chisago County lakes through a partnership with Chisago County. WCD staff also conduct weekly in-lake monitoring for zebra mussels near public boat launches. In 2019, WCD staff discovered an early introduction of zebra mussels on Bone Lake (partners quickly mobilized to treat the new infestation) and prevented zebra mussel introductions into Big Marine and Square Lakes.

Staff from Washington Conservation District and MN DNR work with contractors to install a containment boom at Bone Lake in Scandia, prior to applying an aquatic pesticide to kill zebra mussels.

Happily, WCD’s 2019 watercraft inspection data shows that most people are following state rules requiring boaters to clean and drain watercraft to prevent the spread of AIS. Of 5343 inspections conducted on watercraft entering lakes, only 224 boats had their drain plugs in (4% of inspected watercraft) and 339 had plants or animals attached (6%). Of these, six had zebra mussels attached. Unfortunately, we still need compliance rates to be higher to fully protect our waterways.

This year, the DNR is focusing special attention on shoreline owners and anglers. It is critical for shoreline owners to ensure that docks, lifts, rafts, anchors and other equipment are air dried for 21 days before being sold or installed in new waterbodies to make sure AIS can’t be spread. The DNR offers mandatory training for lake service providers and maintains a list of certified providers on its website.

BML SE 7-27-19
When removing boats, docks, lifts, or other water-related equipment from lakes and rivers, carefully inspect everything to make sure there are no aquatic invasive species (AIS) such as zebra mussels, Eurasian watermilfoil, or New Zealand mudsnails attached.

For anglers, a key message is to dispose of unused live bait in the garbage instead of in the water (a 2019 survey showed that 36% of all anglers have dumped live bait into lakes and rivers in the past). DNR staff are optimistic that they can influence behavior change because shoreline owners and anglers have indicated that they are motivated to follow the rules in order to help prevent the spread of AIS and make a positive impact on their communities and the environment.

To learn more about aquatic invasive species and what you can do to prevent their spread this season, go to