Last modified: Tuesday, September 17, 2013

Aquatic nuisance species

Eurasian watermilfoil

Myriophyllum spicatum

Eurasian watermilfoil grows beneath the water and crowds out other plants by forming extensive mats of thick vegetation. It spreads rapidly through high rates of growth and its ability to reproduce from plant fragments. Native to northern Europe and Asia, this plant arrived in North America sometime in the late 1800s or early 1900s.

Eurasian watermilfoil
Eurasian watermilfoil

Distribution in Utah: Populations are found in Otter Creek Reservoir and Fish Lake.

Identification: Leaflets have a distinct feathery appearance and are arranged in whorls of 4 around a long slender stem growing up to six inches long. Typically, leaflets grow up to an inch and are usually dark green, but sometimes have a reddish tint.

Problem: In nutrient-rich lakes, Eurasian Watermilfoil forms thick stands of tangled stems and vegetative surface mats. The plant can interfere with recreational activities such as boating, fishing and swimming and can often crowd out important native plants.

Means of spreading: Eurasian watermilfoil may become entangled in equipment. Stems can become lodged in any watercraft or sports equipment that moves through the water. Boat trailers are especially susceptible to transplanting this plant.

Management and containment: As with most invasive species, prevention is the best means of containment. Once Eurasian watermilfoil invades a body of water it is almost impossible to eradicate it. Herbicides and mechanical harvesting are often used to control infestations of watermilfoil.

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