Aquatic Invasive Species in Washburn County.

Native to Europe and Asia, purple loosestrife was introduced in North America in the 1800’s for beekeeping and as a garden ornamental. Purple loosestrife has been present in Washburn County for several years.

Purple loosestrife is an aquatic invasive perennial plant that grows 3-7 feet tall and develops a spike of small purple flowers in late summer. The leaves of the plant are oblong and arranged oppositely along a four to six sided stem. Purple loosestrife spreads rapidly and colonizes wetlands, shorelines, and roadside ditches. Thick stands of purple loosestrife crowd out native vegetation and reduce food, shelter, and nesting sites for a variety of wildlife including birds, turtles, and frogs.

Galerucella beetles can be raised and released as a bio-control option for purple loosestrife. The larval stage of the beetles damage the plant by feeding on foliage. With adequate populations the beetles keep the plants from flowering and spreading seeds. These beetles have been released in several locations throughout Washburn County. Purple Loosestrife has also been treated with herbicide applications in several locations within Washburn County.

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Curly-leaf pondweed is a submerged aquatic invasive plant. The leaves of Curly-leaf pondweed are easily distinguished by their rounded tip, prominent mid-vein, finely toothed edges, and wavy or crimped appearance.

Curly-leaf pondweed is found in a wide variety of habitats, although it prefers alkaline and high nutrient waterbodies and typically grows in less than 10 feet of water.

In late fall and early winter, curly leaf pond weed sprouts from rhizomes and turions (overwintering buds) allowing the plant to out compete native species through rapid spring growth. Curly-leaf pond weed can form large, dense mats on the surface of water bodies inhibiting the light necessary for native plant growth and interfering with navigation and recreational activities such as fishing, boating, and swimming.

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Eurasian watermilfoil is a submerged aquatic invasive plant with delicate, feather-like leaves arranged in a whorl around the stem of the plant. One way to distinguish native milfoils from Eurasian watermilfoil is by counting the number of leaflets that make up a leaf. Native milfoil usually has 7-10 pairs of leaflets; whereas, Eurasian water milfoil typically has 12-21 pairs of leaflets. When out of water, the leaves of most native milfoils remain erect and the leaves of Eurasian water milfoil are usually limp.

Eurasian watermilfoil is highly invasive and is capable of forming large, thick mats which interfere with swimming, boating, fishing, and waterfowl hunting. Additionally, Eurasian watermilfoil can have devastating effects on native ecosystems, displacing native aquatic plants and impacting fish and wildlife populations. 

 Eurasian watermilfoil can spread when small fragments of the plant break off and float on water currents or are transported by boater traffic. Eurasian watermilfoil is able to reproduce from small fragments, which sprout roots and are able to colonize new areas.

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The Yellow Flag Iris is a perennial plant that can grow in conditions as versatile as dry uplands, wetlands, or even in floating aquatic mats. Native to Eurasia, the yellow flag iris can grow 3-4 feet tall with sword-shaped upright leaves and white to yellow flowers which bloom from April to June. Once established it can form dense clumps or floating mats that can negatively affect wildlife habitat and species diversity.

Yellow flag iris can produce numerous seeds which can be spread by floating from the parent plant or by rhizome fragments spreading vegetatively. Once the plant is established it can form dense floating mats which can alter wildlife habitat. All parts of the yellow flag iris are poisonous, resulting in loss of food sources for wildlife in areas of significant population.

Seeds are produced in capsules which hang from the flower, each fruit can house as many as 100 seeds which turn from pale to dark brown. Yellow flag iris seeds can float due to a small air space underneath their hard outer casing. Plants can commonly be mistaken for several native plants such as blue flag iris, cattails, or sweet flag species.

View the range of the Yellow flag iris  here. 

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Japanese and giant knotweed are native to Asia and were imported to the United States in the mid 1900’s as ornamental plants, although they are becoming more prevalent in the wild. The plant can reach up to fifteen feet and is easily distinguished by hollow bamboo-like stalks. 

The leaves of Japanese knotweed are up to 6 inches in length with flat or truncated leaf bases; whereas, the leaves of giant knotweed grow up to 12 inches in length and are more heart shaped. The leaves are arranged alternately along a zig-zag stem. The plant produces sprays of small white flowers in late July to August. 

Knotweed is a perennial, meaning that each spring it re-grows from an extensive root system. Japanese and giant knotweed grow extremely fast and form a dense canopy of foliage which blocks sunlight from reaching the ground. As a result, native vegetation is unable to grow beneath a knotweed stand. When knotweed establishes on stream banks, the lack of understory can promote intense erosion, causing soil and knotweed roots to move downstream.

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Zebra mussels are an aquatic invasive mussel species with a D-shaped shell exhibiting alternating black and white stripes. Since they are able to attach to hard surfaces, zebra mussels can clog water intakes and damage equipment such as boat motors. 

When waterbodies are infested with zebra mussels, their shorelines can become littered with sharp shells that impede human recreational opportunities. Additionally, zebra mussels damage ecosystems by harming fisheries and smothering native mussels, snails, and crayfish.

Zebra mussels arrived in the Great Lakes in the late 1980’s from contaminated ballast water. Since that time they have expanded in range via the Mississippi River. Zebra Mussels have been confirmed in both Big McKenzie and Middle McKenzie Lakes, while several area lakes continue to be monitored.

The Washburn County Conservation Department is working with local volunteers to monitor several waterbodies throughout the county. A "plate sampler" is used for monitoring by local volunteers who hang the sampler plates from their docks and check for Zebra Mussels every few weeks.

Zebra mussles have three life stages: veliger, juvenile, and adult. Veligers are microscopic and swim freely in the water column, allowing them to be easily transported to new waterbodies. To test a lake for zebra mussel veligers, three samples of water are collected using a specialized mesh net and collection bottle. They are poured into a plastic container and preserved with a 95% ethanol solution. Samples are sent to a lab where they are tested under a microscope, for presence or absence.

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In 2018 Burnett and Washburn Counties passed a  Decontamination Ordinance  which states, “If available, boaters are required to decontaminate boats, trailers and equipment before entering and leaving a waterbody”. Decontaminating your equipment further minimizes the chances of spreading aquatic invasive species, especially small critters like zebra mussel larvae that the naked eye cannot see.

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