Last modified: Tuesday, September 17, 2013

Aquatic nuisance species

Protect Utah waters. Stop aquatic hitchhikers!

Aquatic nuisance species (ANS) are not native to Utah. They threaten native species' abundance or diversity, stability of aquatic systems and commercial or water recreational use. We focus on these species because they pose a major threat to our water resources, and we might be able to stop their spread or introduction.

These species are harmful because they can:

  • Affect recreation, power and water operations
  • Disrupt the natural ecosystem balance
  • Displace native species
  • Alter native species' food webs

Before leaving a water body, here's what you can do to help control their spread:

  • Inspect your boat and equipment and remove any plants and animals.
  • Drain water from the motor, livewell, bilge or transom well.
  • Never release or transport live aquatic species from one body into another.

Information on individual species

Quagga and zebra mussels

These clam-like mollusks typically have a dark and light zebra-like shell pattern. They are not native to the Americas, but have invaded waters in the eastern United States and the lower Colorado River basin. Both species are very similar and pose a major threat to Utah waters.

New Zealand mudsnail

These snails are tiny with brown swirled cone-shaped shells. Despite their small size, they reproduce quickly and can form dense masses. They disrupt the food chain by consuming algae and competing with other bottom-dwelling animals that fish depend upon.


This tall, perennial reed is common in wetlands around the world. It grows in large colonies and spreads by rhizomes (underground stems) that produce dense stands that crowd out native vegetation. A non-native species of phragmites is choking many of Utah's marshlands.

Purple loosestrife

This perennial plant grows in many different types of wetlands. It soon crowds out native grasses and flowering plants that wildlife depend upon for food. A native of Asia and Europe, purple loosestrife was introduced to the Americas as an ornamental plant in the 1800s.

Eurasian watermilfoil

This plant grows rapidly beneath the water and aggressively competes with native plants. Dense mats of Eurasian watermilfoil clog fisheries, restrict boating, affect water quality and has lower food value for birds and fish than the native plants it displaces.

Whirling disease

Although not a nuisance species in the usual sense, whirling disease is caused by a bacterial parasite found in an increasing number of waters in Utah. Whirling disease affects trout and salmon, causing deformations and neurological damage that cause the fish to "whirl."

For more information
  • 100th Meridian Initiative: A cooperative effort between state, provincial and federal agencies to prevent the westward spread of zebra mussels and other aquatic nuisance species in North America.
  • Protect Your Waters: Stop aquatic hitchhikers! Aquatic nuisance species can hitch a ride on clothing, boats and other items used in the water. When we go to another lake or stream, the nuisance species can be released and establish itself.