Polk County is rich in water resources, boasting 437 lakes and over 300 miles of streams and rivers. An increasing number of lakes are being infested by populations of aquatic invasive species. LWRD staff provide advice and assistance to lake groups and individuals related to identification and management of many invasive species populations.
Aquatic invasive species often leave their predators and competitors behind in their native ecosystems. Without these natural checks and balances they are able to reproduce rapidly and out-compete native species. Once established, they can alter ecological relationships among native species and can affect ecosystems function, economic value of ecosystems and human health.
In the United States, over $137 million is spent annually as a result of invasive species. Since its inception in fiscal year 2004, the Wisconsin Aquatic Invasive Species Grant Program has invested about $9 million in grants to reimburse local projects to monitor and control invasive species.
Description Curly leaf pond weed is a submersed invasive aquatic plant that forms surface mats that interfere with aquatic recreation. It is similar in appearance to many native pond weeds but can be distinguished from others by its unique life cycle. It is generally the first pond weed to come up in the spring and usually dies off and drops to the lake bottom by early July. Curly-leaf pond weed was the most severe nuisance aquatic plant in the Midwest until Eurasian watermilfoil appeared.
The two main problems caused by curly leaf pondweed are: 1) the formation of dense mats in late spring and ealry summer which may interfere with recreation and limit the growth of native aquatic plants, and 2) the mid-summer dieback of the plant which can cause rafts of dying curlyleaf to pile up on shore, increase phosphorus concentrations in the lake and could lead to an increase in algae. Curly leaf pondweed can spread from plant fragments, so it is important to clean all vegetation off your boat and equipment before you leave a water access. Once introduced, curly leaf pondweed spreads rapidly.
A Unique Life Cycle Curly leaf pondweed's unique life cycle gives it competitive advantages over many native aquatic plants. It becomes invasive in some areas because of its tolerance for low light and low water temperatures. These tolerances allow it to get a head start on and outcompete native plants in the spring. Unlike most native plants, curlyleaf pondweed plants remain alive, slowly
growing even under thick ice and snow cover. Therefore, it is often the first plant to appear after ice-out. In mid-summer, when most aquatic plants are growing, curly leaf plants are dying back. Before they die, they form vegetative propagules called turions (harden stem tips) that disperse by water movement. Turions lay dormant during the summer when native plants are growing and most germinate in the fall when most native vegetation has died back.
Control The two main challenges associated with the management of curly leaf are to minimize damage to native plants and to produce long-term control. Curly leaf pondweed can be managed using mechanical methods, herbicides, and habitat manipulation. Mechanical control includes raking, cutting or harvesting vegetation. However it will re-establish from any remaining roots if they aren't eliminated.
There are a small number of aquatic herbicides that can be used to control curly leaf pondweed. Active ingredients that have been successful in treating curly-leaf pondweed include diquat (G), copper with diquat (G), endothall (E), and fluridone (E). E = excellent, G = good Nevertheless, these herbicides only give control in the year of treatment.
Make a note that any chemical control method provides the chance for oxygen depletion. This may occur because of the decomposition of the dead plant material. Oxygen depletion can kill fish in a lake. If the lake is heavily infested with weeds it may
Curly leaf pondweed has been documented on 47 Polk County water bodies as of December 2017.
be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control oxygen depletion.
Water bodies with documentation of curly leaf pondweed include: Alabama Lake, Andrus Lake, Apple River, Apple River Flowage, Balsam Lake, Bear Trap Lake, Big Blake Lake, Big Butternut Lake, Big Lake, Big Round Lake, Black Brook Flowage, Bone Lake (Black Brook), Bone Lake (Georgetown), Bridget Lake, Cedar Lake, Clam Falls Flowage, Deer Lake (Balsam Lake), Deer Lake (McKinley), Dwight Lake, Half Moon Lake, Herby Lake, Horse Lake, Horseshoe Lake, Joel Flowage, Lake O' the Dalles, Little Blake Lake, Little Butternut Lake, Little Mirror Lake, Long Lake (Balsam Lake), Long Trade Lake, Lotus Lake, Loveless Lake, Magnor Lake, McKenzie Lake, North Twin Lake, North White Ash Lake, Pike Lane, Pine Lake (Alden), Round Lake (Laketown), Sand Lake, Sandhill Lake, South Twin Lake, Staples Lake, Tarbert Lake, Unnamed (Beaver), Wapogasset Lake, and White Ash Lake.
Curly leaf pondweed was first discovered in Polk County in the Apple River Flowage in 1977. As of December 2015, curly leaf pondweed was documented in forty-two water bodies in Polk County. The Polk County Land and Water Resources Department documented the species in five additional water bodies in 2016-2017: Andrus Lake, Joel Flowage, Lotus Lake, Round Lake (Laketown), and Tarbert Lake.
Eurasian water milfoil is a submersed aquatic plant native to Europe, Asia, and northern Africa. It is the only non-native milfoil in Wisconsin. Like the native milfoils, the Eurasian variety has slender stems whorled by submersed feathery leaves and tiny flowers produced above the water surface. The flowers are located in the axils of the floral bracts, and are either four-pedaled or without petals. The stem thickens below the inflorescence and doubles its width further down, often curving to lie parallel with the water surface as much as 33 feet in length and frequently forming dense mats and/or canopies. Eurasian water milfoil is can be difficult to distinguish from Northern water milfoil. Eurasian water milfoil has 9-21 pairs of leaflets per leaf, while Northern milfoil typically has 7-11 pairs of leaflets.
Ecological Threat Eurasian milfoil is highly invasive and is capable of forming large, think mats which interfere with swimming, boating, fishing, and waterfowl hunting. Additionally, Eurasian water milfoil can have devastating effects on native ecosystems, displacing native aquatic plants and impacting fish and wildlife populations.
Habitat in the United States
Eurasian water milfoil was first discovered in North America in the 1940's. Since this time, Eurasian water milfoil has invaded nearly every state in the United States. Eurasian water milfoil can spread when small fragments of the plant break off and float on water currents or are transported by boater traffic. Eurasian water milfoil is able to reproduce from small fragments, which sprout roots and are able to colonize new
Establishment of Eurasian water milfoil populations in Polk County has occurred relatively recently. Eurasian water milfoil was first found in Polk County in Long Trade Lake in 1995. Long Trade Lake is part of the Trade River System, which includes Little Trade Lake, Big Trade Lake, and Round Lake in Burnett County. Eurasian water milfoil was discovered in Round Lake in 2003 and in Little Trade Lake in 2009. In addition to the Trade River System, Eurasian water milfoil was found in Horseshoe Lake in 2006, in Pike Lane in 2010, in the St. Croix River between Spanglers Landing and Lions Park Landing in 2013 and in Cedar Lake in 2015.
Control Many methods have been tried in the United States to contain or eliminate Eurasian watermilfoil. The control methods can be classified as chemical or physical. Biological control methods (control with living predators) are still in the research and development stage. Chemical control methods have been based primarily on the use of 2,4-D because the plant is highly susceptible to it.
Physical control has involved the use of mechanical harvesters, underwater rototillers and cultivators, diver-operated dredges, water draw down, and the use of fragment barriers to prevent spread.
Mechanical harvesters offer relatively fast reduction in Eurasian watermilfoil biomass, however, the plant quickly regrows and the artificial creation of a large number of fragments can enhance the spread of the plant. Underwater tilling and cultivating uproot the plants and allow them to float away which is more effective in clearing a site of Eurasian watermilfoil than harvesting. It
Eurasian water milfoil has been documented on 5 Polk County waterbodies as of December, 2017: Cedar Lake, Horseshoe Lake, Long Trade Lake, Pike Lake and St. Croix River
is, however, a slow and costly operation that frees a large number of plant fragments that are then able to spread to new sites.
Fragment or bottom barriers are physical covers placed over the colony to prevent fragmentation spread. It has been found useful for small infestations but is expensive and requires regular maintenance.
St. Croix River Eurasian Water Milfoil Monitoring
In 2013, the Land and Water Resources Department discovered Eurasian water milfoil in the St. Croix River between Spanglers Landing and the hydro-electric dam in St. Croix Falls.
In both 2014 and 2015, water levels on the St. Croix River were lowered for dam maintenance. As a result, most sites with Eurasian water milfoil were above water with the exception of a few large bays with tributaries flowing to the St. Croix River. In 2014, volunteer opportunities to hand pull Eurasian water milfoil were organized to take advantage of the fact that most plants were above the water line and more easily accessible. Additional drawdowns occurred in October 2016, March 2017 and November 2017.
In 2016, water levels were extremely high on the St. Croix River, making surveying for Eurasian water milfoil nearly impossible. The area from Nevers Dam to Spanglers Landing was surveyed for Eurasian water milfoil in August 2017. Likely as a result of low water levels, the 2015 and 2017 populations of Eurasian water milfoil were substantially reduced. The Land and Water Resources Department and St. Croix River Association assessed milfoil growth in November 2017 during the drawdown and were only able to find milfoil in one area of the bay.
Chinese Mystery Snails were imported to the west coast in the late 1800's as a food source for the Asian market and have spread via aquarium release and other accidental and intentional introductions. When introduced to a new water body, Chinese mystery snails alter the ecosystem composition, structure and function by competing with native snails for food and space.
The shell of the Chinese mystery snail is smooth and strong. It is a uniform color throughout without banding and is usually a light to dark olive-green. The shell can have 6 to 7 whorls. The whorls are strongly convex and each suture is very indented. The outer lip is either round or oval and has a black color to it. The shell can grow to a couple of inches in length.
Chinese mystery snails can serve as vectors for the transmission of parasites and diseases. Some of the parasites and diseases that the Chinese mystery snail has been know to play host to can infect humans. Their shells will clog the screens of water intake pipes inhibiting the flow of water. Also, they naturally compete with our native snails for food and space.
Specific control methods for the Chinese mystery snail have yet to be developed but there are some general snail management techniques that could be applied. The best type of control is prevention. Preventing any further spread of the Chinese mystery snail will help keep our native ecosystems healthy. To help stop the spread of the Chinese mystery snail, a few simple steps should be followed:
Learn to identify the Chinese mystery snail and other exotic snails.
If you have snails or other animals in an aquarium and you no longer wish to care
Bodies of water in Polk County with documented Chinese Mystery Snails
for them, you should euthanize the animals before disposing them in the trash. Do Not Release Them In The Wild!
Remove mud, plants, fish, and animals from all your equipment and drain all water from the bilage and livewells before leaving the launch area.
Clean your equipment with hot water or a pressure washer.
Never release plants or animals into a different body of water from which they came.
Populations of Chinese mystery snails are now established in many Northern Wisconsin Lakes. As of December 2015, Chinese mystery snails were documented on thirty-eight Polk County waterbodies. The Polk County Land and Water Resource Department documented the species in nine additional waterbodies in 2016-2017: Bass Lake, Big Butternut Lake, Joel Flowage, Little Mirror Lake, Long Lake (Johnstown), Loveless Lake, Rice Lake (Alden), Round Lake (Laketown) and Wind (Round) Lake.
Chinese mystery snails have been documented on 47 Polk County waterbodies as of December 2017 including: Antler Lake, Apple River, Balsam Lake, Bass Lake, Bear Trap Lake, Big Blake Lake, Big Butternut Lake, Big Lake, Big Round Lake, Black Brook Flowage, Bone Lake, Camelia Lake, Cedar Lake, Church Pine Lake, Clam Falls Flowage, Clear Lake, Deer Lake, Half Moon Lake, Horseshoe Lake, Joel Flowage, Largon Lake, Little Blake Lake, Little Mirror Lake, Long Lake (Johnstown), Loveless Lake, Lower Pine Lake, Magnor Lake, McKenzie Lake, Middle Pine Lake, North Pipe Lake, North Twin Lake, North White Ash Lake, Pike Lake, Pine Lake, Pipe Lake, Rice Lake (Alden), Round Lake (Laketown), Sand Lake, Sandhill Lake, Silver Lake, South Twin Lake, Staples Lake, Swede Lake, Wapogasset Lake, Ward Lake, White Ash Lake and Wind (Round) Lake.
Spiny water flea are not actually insects, but are tiny crustaceans, related to shrimp and lobster. They get their name because they have a long, sharp barbed tail spine. They are large zooplankton measuring about 1 centimeter in length and are active from late spring to late fall. Spiny water fleas can rapidly reproduce in summer because adult females can produce young without mating, at a rate of 10 young every two weeks. Because spiny water fleas eat zooplankton, they compete directly with small fish that also need to eat zooplankton. Research shows that perch aren't growing like they should and some young can't survive because of the lack of food. Young fish have trouble eating these waterfleas due to their long, spiny tails. A decrease in small fish populations could also take away a food source for larger sport fish. Because the fleas don't have many predators, their populations grow rapidly as they continue to eat up much of the zooplankton.
Fishing, boating, and other water recreational equipment can transport spiny waterfleas and their eggs to new water bodies. Their resting eggs can survive long after the adults are dead, even under extreme environmental
Help Stop the Invasion Because spiny water flea eggs and adults can get into bilage water, bait buckets and livewells in boats if not monitored closely, care must be taken not to transport water between water bodies. Also fishing lines and downriggers will often be coated with both eggs and adults. They can be carried to a new lake and introduced there if water is dumped out of a boat, bait bucket or livewell.
Unfortunately, at this time no effective strategy is available to control spiny water fleas once they are introduced into lakes. Therefore, education is key for preventing this aquatic hitchhicker. Scientists say that the spiny water flea is now a permanent member of many fresh water lakes in the midwest. Anyone who thinks they may have spotted spiny water fleas in any Polk County lakes, please report the findings to Jeremy at Land and Water Resources, 715-485-8639 or to the Wisconsin Department of Natural Resources. Don't let spiny water fleas tag along on your next fishing trip! Check your boat's bilage water, bait buckets, livewells and fishing lines for both eggs and adults before you leave the lake.
The zebra mussel is a tiny (1/8" to 2") bottom-dwelling clam native to Europe and Asia. Zebra mussels were introduced into the Great Lakes in 1985 and have been spreading throughout them since that time. They were most likely brought to North America as larvae in ballast water of ships that traveled from fresh-water Eurasian ports to the Great Lakes. Zebra mussels look like small clams with a yellowish or brownish D-shaped shell, usually with alternating dark - and light-colored stripes. They can be up to two inches long, but most are under an inch. Zebra mussels usually grow in clusters containing numerous individuals. Zebra mussels are the only fresh-water mollusks that can firmly attach themselves to solid objects - submerged rocks, dock pilings, boat hulls, water intake pipes and other mussels. They are generally found in shallow (6-30 feet deep), algae-rich water.
Distribution/Habitat Zebra mussels were first found in Wisconsin waters of Lake Michigan in 1990. By 1991, the mussels had made their way into Pool 8 of the Mississippi River, most likely originating in the Illinois River. Populations of zebra mussels are steadily increasing to over several thousand per square meter in some portions of the Mississippi River. As of 2003, their distribution included the entire Wisconsin portion of the Mississippi and extended up to Stillwater in the St. Croix River. With females producing up to 1 million eggs per season, and adults colonizing any hard surface that's not toxic, the spread of zebra mussels needs to be controlled.
Effects of Invasion Because zebra mussels feed by drawing water into their bodies and filtering out most of the suspended microscopic plants, animals, and debris for food, their presence can lead to a depleted food supply for other aquatic organisms, including fish. Although zebra mussels can initially result in clearer water, the resulting higher light penetration fosters growth of rooted aquatic plants which although creating more habitat for small fish, may inhibit the larger, predatory fish from finding their food. This thicker plant growth can also interfere with
boaters, anglers and swimmers. Zebra mussel infestations may also promote the growth of blue-green algae, since they avoid consuming this type of algae but not others.
Eonomic Impact Zebra mussel invasions are cause for serious concern. They have caused millions of dollars of economic losses, declines of native species, and have dramatically altered aquatic ecosystems. These small mussels clog water intakes and damage equipment by attaching to boat motors or any hard surface. They can damage ecosystems by farming fisheries, smothering native mussle and crayfish and littering beaches with their sharp shells. Zebra mussels also attach to the shells of native mussels in great masses, effectively smothering them.
Industries spend millions to clean pipes fouled by zebra mussels and these costs are passed to the consumer. Lock and dam operators on the Mississippi River and raw water users have also incurred costs. The estimated annual cost of controlling zebra mussels in the Great Lakes now range from $100 to $400 million.
Environmental Impact In addition to economic impacts, zebra mussels can have a profound environmental impact. A huge population of zebra mussels can damage an ecosystem's sustainability as it damages the base of the food web having the potential to destabilize the entire ecosystem. Mussels accumulate organic toxins, and then excrete these same toxins and pass these toxins up the food chain. Biological effects on other species include: loss of cover, nesting sites and forage; changing competitive relationships; fouling native mussels; and changing food availability.
Zebra mussels are native to freshwater rivers and lakes in Eastern Europe and Western Asia and 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. In September 2016, a single adult zebra mussel was found on the northeast side of Deer Lake by a citizen.
Zebra Mussel Discovery and Task Force
On September 2, 2016, a single adult zebra mussel was
found on the northeast side of Deer Lake by a citizen. The specimen was identified by the Land and Water Resource Department and brought to the Wisconsin Department of Natural Resources for verification.
Later the same week, representatives from the Land and Water Resource Department, the Deer Lake Improvement Association, and U.S. Fish and Wildlife Service searched the shallow water in the vicinity where the zebra mussel was found and at the public access. No additional zebra mussels were found at this time.
In September, the Deer Lake Improvement Association sent out email and mail notices to lake residents with information regarding the zebra mussel that was found. The notices provided a description of zebra mussels and encouraged residents to check docks and boats as they were pulled from the water for the season. The Association also informed dock service providers about the zebra mussel discovery and requested that they check docks and equipment pulled out of Deer Lake. In late October, volunteers checked docks and lifts pulled out of Deer Lake.
In response to this discovery, the Land and Water Resource Department and Harmony Environmental organized a Zebra Mussel Task Force to coordinate a zebra mussel monitoring effort for Deer Lake and additional Polk County lakes and rivers. Partners from the Deer Lake Improvement Association, Harmony Environmental, Bone Lake Management District, Polk County Land and Water Resources Department, St. Croix River Association, Wisconsin Department of Natural Resources, National Park Service, and U.S. Fish and Wildlife Service attended two meetings of the Polk County Zebra Mussel Task Force. These meetings occurred on January 20 and February 9, 2016 and were facilitated by Harmony Environmental.
At the first meeting, the current status of zebra mussels in Deer Lake, Big McKenzie Lake (Burnett/Washburn County), the St. Croix River, Bass Lake (St. Croix County), and Minnesota was discussed. A matrix on monitoring methods and a 2017 monitoring plan for Deer Lake was created at the meeting. Additionally, a basic monitoring plan for lakes without zebra mussels and priority/destination
lakes was created. Lastly, a list of methods and messages for a countywide zebra mussel monitoring and prevention outreach strategy was compiled.
During the second meeting, an example zebra mussel monitoring worksheet was presented by the National Park Service. Rapid response grants were discussed and the group decided it was un-necessary to apply for a grant for the 2017 season. Additionally, tasks were assigned for the countywide zebra mussel monitoring and prevention outreach strategy.
The following monitoring efforts were undertaken on Deer Lake and additional Polk County water bodies in 2017:
Cinder block and plate sampler monitoring by the Deer Lake Improvement Association with suspect specimens reviewed by the Land and Water Resources Department
Plate sampler and substrate examination at the Deer Lake boat landing and additional Polk County water bodies by U.S. Fish and Wildlife Service
Plate sampler and substrate examination at the site where the zebra mussel was found by the Land and Water Resources Department
Shoreline searches and substrate examination at the site where the zebra mussel was found by the Deer Lake Improvement Association
Smart prevention protocol on Deer Lake (including veliger tows) by the Land and Water Resources Department and the St. Croix River Association
Veliger tows on Deer Lake, Bone Lake, Balsam Lake, and two sites on the St. Croix River by the National Park Service, St. Croix River Association, Land and Water Resources Department, Deer Lake Improvement Association, and Bone Lake Management District.
The Land and Water Resources Department also made zebra mussel plate sampler supplies obtained from the Wisconsin Department of Natural Resources available to Polk County waterbodies. As a result, a total of fifty-five plate samplers were placed on the following lakes and monitored by volunteers: the Apple River Flowage, Balsam Lake, Bear Trap Lake, Big Blake Lake, Big Round Lake, Big Lake, Bone Lake, Cedar Lake, Church Pine Lake, Deer Lake, and Wapogasset Lake.