Invasive species fact sheets

Aquatic Invasive Species


Pilot projects to control zebra mussels

Starting in 2015, the Minnesota Department of Natural Resources permitted pilot projects to kill zebra mussels in public waters. These pilot projects are the only projects in the state to be permitted.

How are zebra mussels currently controlled?

In the U.S. and Canada, facility managers use pesticides to kill zebra mussels in closed systems, such as water-cooling systems of power plants, in order to maintain functioning infrastructure. Many of the pesticides used in close systems are not allowed for use in open water. In open systems such as natural lakes, attempts to control zebra mussels are uncommon and considered experimental at this time.

Treatments of zebra mussels in Minnesota lakes

Year

Location

Treatment Type

Result

2016

Lake Minnewashta (Carver County)

EarthTec QZ® (copper product)

Post-treatment monitoring will occur in spring 2017.

2015

Ruth Lake (Crow Wing County)

EarthTec QZ® (copper product)

Adult zebra mussel found outside treatment area in fall 2016. Post-treatment monitoring will continue through 2018.

2014 - 2015

Christmas Lake (Hennepin County)

Zequanox®, some physical removal, EarthTec QZ® (copper product), potassium chloride

Zebra mussels found lakewide post-treatment.

2014 - 2015

Lake Independence (Hennepin County)

EarthTec QZ® (copper product), potassium chloride

Zebra mussels found near boat access post-treatment.

2011

Rose Lake (Otter Tail County)

Cutrine Ultra® (chelated copper)

Adult zebra mussel reported in 2016 (no zebra mussels had been found since 2012).

2011

Lake Irene (Douglas County)

Cutrine Ultra® (chelated copper)

Zebra mussels found post-treatment.

2000

Lake Zumbro (Olmsted County)

Mussels exposed to air by lowering water level

Zebra mussels found post-treatment, survived in remaining water.

 

Which pesticides are used to kill zebra mussels?

Several pesticides have been used to control zebra mussels in Minnesota:

Pesticides that are approved for use in controlling zebra mussels in open water:

  • Zequanox®, a biological pesticide; and
  • copper products, such as copper sulfate

Pesticides that were used with special permission:

  •  potassium chloride (also known as potash or muriate of potash; use in open water requires review and approval from the U.S. Environmental Protection Agency).
Applying Zequanox to Christmas Lake in September 2014
Applying Zequanox® to Christmas Lake, September 2014

Whether a pesticide is effective will depend on factors like concentration, duration of exposure, and water temperature. Application of pesticides may require installation of a temporary enclosure around the treatment area. Pesticides may also harm other aquatic life.

What results can we expect?

Because pesticides have rarely been used to control zebra mussels in open water, pilot projects in Minnesota will help answer this question. In situations where zebra mussels are found in an isolated area or in a small water body, it may be possible to kill all the target zebra mussels using pesticides. Even if the mussels are killed, their shells will persist and can remain attached to surface even after the animals are dead.

What pilot projects will the DNR permit?

Most lakes that are currently infested with zebra mussels are not good candidates for these pilot projects and permits. Pilot projects would be more likely to be permitted in situations where:

We will assess all proposed projects on a case-by-case basis.

What monitoring will the DNR require for zebra mussel pilot projects?

The DNR will require the permittee or their partners to conduct pre- and post-treatment monitoring to evaluate the effects of treatments in Minnesota. The Minnesota Aquatic Invasive Species Research Center at the University of Minnesota developed a monitoring protocol that includes guidance for: zebra mussel population assessments, mortality monitoring, water chemistry monitoring, and long-term monitoring after treatment.

Will the DNR pay for zebra mussel pilot projects?

The DNR may provide support, but the applicant should be prepared to cover the costs of pesticide treatment and monitoring.

Who may apply for a zebra mussel pilot project?

A local unit of government, a tribal government, or a lake association may apply to the DNR to carry out a zebra mussel pilot project. Contact your area invasive species specialist to discuss your potential project. The DNR may also initiate pilot projects. If your proposal does not qualify for a pilot project, other control options may be appropriate. A DNR permit will likely be required for any removal or disposal of zebra mussels.

There are no zebra mussels in this lake yet - what can I do?

Monitoring is the best way to detect a new infestation of zebra mussels. Look for zebra mussels on boat hulls, swimming platforms, docks, aquatic plants, wood and other objects along shorelines of lakes and rivers. Contact the Minnesota Aquatic Invasive Species Research Center for resources and support through the University of Minnesota Extension Service.This link leads to an external site.