DNR, Lake Groups, and Local Government Partners Work to Keep Aquatic Invaders at Bay

The number in Washington County is up to 22. In Chisago County it is 12. Anoka has 16 and Ramsey has 29. Statewide, approximately 5% of the 11,000 lakes in Minnesota are now infested by aquatic invasive species (AIS). AIS are non-native plants and animals that threaten the health of our rivers, lakes and streams and cause millions of dollars of problems for local communities. Well known threats include zebra mussels, Eurasian watermilfoil, and spiny water flea. Meanwhile, curly-leaf pondweed and common carp (so common that we’ve put the word in their name) have become so prolific that the Minnesota Department of Natural Resources (DNR) is no longer even tracking them on its infested waters list.

Click the map above to see which Minnesota lakes and rivers are infested by aquatic invasives.

Once introduced to a body of water, AIS typically spread quickly and are expensive and nearly impossible to remove.  To prevent the spread of AIS, Minnesota law requires all boaters to clean and drain boats, trailers and other equipment after coming out of the water and to dispose of unwanted bait, including minnows, in the trash.

As of August 2016, the Minnesota DNR has identified 121 lakes, rivers and wetlands infested with zebra mussels, including Forest Lake, White Bear Lake, and the St. Croix River south of Stillwater.

Zebra mussels attached to a native mussel. Photo from Echo Lake Aquarium.

In an effort to slow the spread of aquatic invaders, the Minnesota legislature has begun to allocate funding to counties for aquatic invasive species prevention efforts such as watercraft inspections, AIS treatment efforts, early detection monitoring, and public education. Projects in Washington County receiving funding for 2017 include:

  • Big Marine Lake Association- $12,000 to treat Eurasian watermilfoil
  • Carnelian-Marine-St. Croix Watershed District- $9,000 to keep Eurasian watermilfoil in Long Lake from moving downstream into Terrapin and Mays Lakes, which are located within Warner Nature Center
  • Clear Lake Association- $7,000 to treat Eurasian watermilfoil
  • Comfort Lake-Forest Lake Watershed District- $9,000 to treat flowering rush and $17,000 to conduct watercraft inspections
  • Lake Demontreville and Olson Association- $8,000 to treat Eurasian watermilfoil
  • Lake Elmo Lake Association- $8,000 to treat Eurasian watermilfoil
  • Croix River Association- $1,200 for outreach to Marinas; and
  • Washington Conservation District- $61,500 to conduct hands-on AIS identification workshops at Forest Lake, Big Marine, and Lake Elmo; Send 10 citizens to the University of Minnesota AIS Detectors certification program; conduct seasonal watercraft inspections ; monitor priority launches and lakes to detect new AIS infestations, and; coordinate rapid response teams for area lakes.

Information collected during watercraft inspections in 2016 indicates that recent education efforts are paying off. Most people are following the rules, especially when it comes to removing plants and mud from their boats. Of the 1,587 inspections performed by the Washington Conservation District in 2016, there were only 15 AIS violations observed on boats coming into lakes.  Twelve people had plants attached to their boats or trailers and three had failed to drain water from their boats. On Forest Lake, Comfort Lake – Forest Lake Watershed District and DNR inspectors conducted 3,147 surveys and found 32 watercraft entering with water, weeds or mud attached. In all of these cases, inspectors ensured that the watercraft were cleaned and drained before entering the lakes.

Unfortunately, there continue to be more drain plug violations in Washington County than in other parts of the state. Inspectors find 7% of boats arriving at launches with their drain plugs in, even though the law requires plugs to be out during transport.

Watercraft inspectors are stationed at public launches throughout Washington County and other parts of Minnesota to ensure that boaters don’t accidentally transport aquatic hitchhikers.

Next month, the Washington Conservation District will hold three hands-on AIS identification workshops to help people learn how to identify curlyleaf and Eurasian-water milfoil, the two most common invasive plants in nearby lakes. People will also learn how to identify common native plants such as coontail, chara and northern milfoil. The workshops will be held on Mon., June 19 in Forest Lake, Wed., June 28 at Lake Elmo Park Reserve, and Thu., June 29 at Big Marine Park Reserve. Get additional details and RSVP at www.tinyurl.com/AISID17.