The distribution of zebra and quagga mussels in the U.S. as of July 2017

Invasive zebra and quagga mussels alter ecosystem dynamics and affect industrial, municipal, and recreational water users. The negative impacts of these dreissenid mussels drove scientists to search for effective control methods beginning in the early 1990s.

Since then, researchers have uncovered various control methods, each with their own advantages and disadvantages. Both chemical and physical treatments have been developed and used by state and federal agencies in the control of zebra mussels.

Physical Treatments

Benthic Mats

  • Benthic mats are large, dark tarps that are anchored to the bottom of a water body.
  • Benthic mats control invasive mussels by restricting water flow through the mats, withholding oxygen and food from the mussels beneath the mats, and blocking light to prevent photosynthesis from producing oxygen beneath the mats. In some cases they prevent larval mussels (veligers) from spreading.
  • Benthic mats were used by the Texas Parks and Wildlife Department to treat zebra mussels in Lake Waco, TX beginning in 2014.

Water Drawdowns

  • Water drawdowns occur when managers decrease the maximum depth in a body of water.
  • Drawdowns work to fight invasive mussels by exposing more shoreline and decreasing the capacity of the remaining water to retain heat. The exposure of mussels to freezing temperatures inhibits their ability to function and may kill them, depending on the length of the drawdown.
  • Winter water drawdowns were used to treat Lake Zumbro, MN and Edinboro Lake, PA in 2000 and 2001. A complete drawdown of Lake Zorinsky, NE, in 2010 resulted in the eradication of zebra mussels within the lake, and the lake was refilled and re-opened for recreation in 2012.

UV Light

  • Exposure of water to UV light has the potential to prevent veligers from settling within water pipes and subsequently growing into adhered mussel populations.
  • The light damages DNA and protein within the veligers and can be lethal at appropriate wavelengths and dosages.
  • UV light has been evaluated by several hydropower facilities, including Hoover Dam, NV in 2010 and Ontario Hydro, ONT in 1999.

Chemical Treatments

Carbon Dioxide and pH manipulation

  • Carbon dioxide is a naturally occurring gas that is a byproduct of respiration.
  • Carbon dioxide causes a decrease in pH in the water column, creating a weak carbonic acid that is toxic to mussels, who are unable to regulate their internal pH levels.
  • pH manipulation through the addition of carbon dioxide is currently undergoing field testing in Candlewood Lake, CT.

Potassium Chloride

  • Potassium chloride, also called potash, is a salt compound that is commonly found in fertilizers.
  • Potash interferes with mussels’ respiratory systems, preventing them from breathing. Potash affects both native and invasive mussels, but does not affect fish or plants.
    • Biobullets® is a commercially available treatment that packages potassium chloride within an edible shell to encourage consumption by invasive mussels.
  • Potash was used to eradicate zebra mussels from Millbrook Quarry, VA, in 2006 and was used in conjunction with other control methods to treat localized zebra mussel infestations in Christmas Lake, MN in 2015.

Copper Compounds

  • Copper compounds may differ in specific elemental makeup, but each share copper as a main component.
  • Copper compounds are toxic when ingested by mussels.
    • Earthtec QZ® maintains copper as a biologically active cupric ion. This compound has been used to treat Independence Lake, MN, Ruth Lake, MN, and was used in conjunction with other control methods to treat localized zebra mussel infestations in Christmas Lake, MN in 2014 and 2015.
    • Chelated copper compounds consist of copper ions bound with amino acids. A commercially available copper chelate, Cutrine Ultra®, was used to treat Lake Irene, MN, and Rose Lake, MN in 2011.
    • Copper sulfate was used to treat a lake on Offutt Air Force Base in Omaha, NE in 2008 and 2009.


  • Zequanox® is a compound that utilizes the killed-cells of a specific strain (CL145A) of a common soil bacterium, Pseudomonas fluorescens, as its active ingredient.
  • When ingested, Zequanox®  deteriorates the digestive lining of zebra and quagga mussels, causing death.
  • Zequanox® is currently in use by the Tip of the Mitt Watershed Council to treat inland lakes in northern Michigan, and was used in conjunction with other control methods to treat localized zebra mussel infestations in Christmas Lake, MN in 2015.

Each new development in control technology represents an exciting potential technique to manage invasive mussels. To best utilize the different tools that managers may have access to, diverse management goals must be identified and understood in order to move forward with a joint and strategic approach to managing invasive mussels. Further investigation is needed to address uncertainties in the use of each control method, including potential side effects on invertebrates and ecosystems, and optimal application procedures. The coordinated and integrated application of several different control tools has been proven to yield the most effective control strategy for other invasive species. Consequently, research should continue to identify the next set of control tools (e.g., spawning inhibitors and microparticles to target control agent delivery).

Before: A native mussel covered in invasive zebra mussels before Zequanox treatment
After: The native mussel survived a Zequnox treatment while the invasive mussels were eradicated

Management and Action Plans

Developing Best Management Practices for Control

Management and Control Projects

Get In Touch

Erika Jensen
Great Lakes Commission
(734) 971-9135

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