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AIS SPOTLIGHT: signal crayfish


Signal crawfish have a distinctive white or turquoise patch at the claw hinge. Image courtesy rdclark via iNaturalist.

A new invasive crayfish - the Signal crayfish was found in Lake Winona, near Alexandria late last Fall. Signal crayfish are native to the Pacific Northwest but have been found in parts of California and Europe and now in Minnesota. The most distinguishing feature is a white or turquoise patch on the top at the claw hinge. Read more here at MAISRC's website.

Aquatic Invasive Species Survey Report

by Carolyn Dindorf, Limnologist, Bolton & Menk, Inc.

The purpose of the survey was to search for aquatic invasive species (AIS) in Lake Independence, with particular attention to Starry Stonewort (Nitellopsis obtusa). However, both invasive and native plants and animals that were found were identified. This was a partial survey, not a complete survey of the lake.


















The survey was conducted using double rake samplers by members of the Lake Independence Citizens Association with technical assistance from Carolyn Dindorf, a Limnologist with Bolton & Menk, Inc. Two double-sided rake samplers were used and were thrown from each end of the pontoon boat to increase the number of samples and area surveyed.  A depth finder was used to identify areas of vegetation. There was a substantial amount of blue green algae in the water limiting light penetration.  A visual search was not possible due to the algae growth, other than floating plants and any plants that reached the surface. Vegetation was mainly found at depths of 7’ and shallower. But some areas up to 11’ were sampled. Rake loads of vegetation were brought up and placed in a container and sorted through to identify species present.

The survey started at the Three Rivers Park District boat access and continued northwest along the east shoreline in varying depths and then over to the emergent vegetation island and along the north and east side of the island. The north side of the TRPD access was surveyed as well as the area around the City of Independence access. Approximately 2 to 2.5 hours of time was spent on the lake and an estimated 10,000 feet of shoreline was surveyed. A gps track was recorded.

The Results:
No Starry stonewort was found during the survey.  The dominant plant was coontail (Ceratophyllum demersum).   Overflowing rakes of coontail were found on many of the rake tosses.  It was the only plant in most of the samples.  Some Eurasian watermilfoil was found, but very little.  Many of the plants had a lot of zebra mussels on the stems and roots.  There were large clumps of zebra mussels on the roots of the milfoil and coontail and one flat-stem pondweed (Potamogeton zosteriformis).  A curly-leaf pondweed (Potamogeton crispus) turion with a zebra mussel attached was also found. There was a lot of cattail (Typha sp.) on the shoreline and some bulrush along the emergent vegetation island.  The emergent vegetation island had the greatest plant diversity of the areas surveyed. 


Mike commented that he had noticed that the Eurasian watermilfoil had disappeared around his shoreline after the zebra mussels came in and attached to the roots.

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Approximate survey track

Thanks to LICA members Pat and Dick Wulff, Joel Settles, Merry Peticlair, Mike Garwood, Jim Klancke for their hands-on work surveying the lake for AIS.

Check for AIS when removing docks and lifts


When removing boats, docks, lifts, or other water-related equipment this Fall, carefully inspect everything to make sure there are no aquatic invasive species (AIS) such as zebra mussels, Eurasian watermilfoil, or New Zealand mudsnails attached.

If you find any AIS please snap a picture and send details to us at

Zebra Mussel Update

by Mike McLaughlin, LICA Board Member

Zebra mussels (Dreissena polymorpha) are an invasive, fingernail-sized mollusk that is native to fresh waters in Eurasia.They are native to the Caspian and Black Seas south of Russia and Ukraine. They are easy to identify, with a distinct, flat-bottomed ‘D’ shape to their shells that allows them to sit flat against a solid surface, and black, zigzag stripes against a cream background that earned them their name. They grow around two inches long at most, and are microscopic in their larval stage, which is known as a “veliger.” They are short-lived (between two and five years), and begin reproducing at two years of age. Each female can release up to a million eggs per year. Their name comes from the dark, zig-zagged stripes on each shell. The theory is that zebra mussels probably arrived in the Great Lakes in the 1980s via ballast water that was discharged by large eastern European ships. They have spread rapidly throughout the Great Lakes region and into the large rivers of the eastern Mississippi drainage. They have also been found in Texas, Colorado, Utah, Nevada, and California. Zebra mussels negatively impact ecosystems in many ways. They filter out algae that native species need for food and they attach to--and incapacitate--native mussels. Power plants must also spend millions of dollars removing zebra mussels from clogged water intakes.

Klancke dock zebra monitor Sept 2021 - 2.jpg

“Biofouling,” or the accumulation of adult zebra mussels on almost any surfaces put in the water, is one of the more notable impacts zebra mussels can have on a local economy. Zebra mussels are armed with rootlike threads of protein, called “byssal threads,” that allow them to firmly attach themselves to hard surfaces such as rocks, native mussels, docks or boats. Typically, this isn’t a problem for boats that are only in the water for short trips, but boats, docks or intake pipes that are left in the water for a long period of time can become encrusted and be very difficult to clean. If a boat owner also fails to drain the water from his or her motor, any veligers floating in the water will root themselves and clog the machinery as they reach adulthood.

Biofouling is a problem in the ecological world as well. Zebra mussels will attach to native mussels much like they do docks, and in large enough numbers can prevent the natives from moving, feeding, reproducing, or regulating water properly causing their local extinction. The zebra mussels also outcompete the natives for food and space, and because of their fast reproduction can quickly overwhelm a water system. Viewed up-close underwater, two tiny siphons can be seen projecting into a narrow gap between the shell valves of each animal — these siphons are used to pump water for respiration and feeding.

The feeding habits of zebra mussels can also have a drastic impact on an infested lake because of the way they siphon particles of plankton from the water. They are highly efficient at this, and a large population of mussels can quickly clear the water of almost all floating particles. They cause damage by consuming organisms like zooplankton, which can make it harder for species at higher levels of the food chain to find sufficient food. This change can cause shifts in local food webs, both by robbing food from native species that feed on plankton and also by increasing water clarity and thus making it easier for visual predators to hunt.The mussels can also promote algae blooms through this filter feeding process in which the mussels consume just some forms of algae that are beneficial to the ecosystem while refraining from eating detrimental varieties like blue-green algae.

In an effort to reduce zebra mussel populations, a paper released by the University of Minnesota in partnership with the U.S. Geological Survey demonstrated the most effective ways to eradicate the inch-long nasties, even in the icy waters of our state. Most chemicals used to exterminate zebra mussels are developed and tested in the warmer states located south of Minnesota, said James Luoma, a USGS researcher who was one of the leaders of the study. While these chemicals may work efficiently in warmer climates, they do not operate as well in the frigid waters of Minnesota lakes in the fall, he said. “A lot of these infestations are found late in the year when people are removing equipment such as docks or boats,” Luoma said. “In the past, [those treating zebra mussels] did not have the information available to [determine if] a product would be effective in cold waters.”

MAISRC, the Minnesota Aquatic Invasive Species Research Center, has completed sequencing of the genome of the zebra mussel in order to isolate markers to study spread and explore possible genetic weaknesses that can be targeted for control. And now, researchers have discovered how to most efficiently kill the mussels in Minnesota lakes without overusing the chemicals. The results of the study indicate that three zebra mussel treatments have the ability to exterminate more than 90 percent of the invasive populations in water temperatures of 45 degrees Fahrenheit. EarthTecQZ, Niclosamide, and Zequanox. Niclosamide, required only 24 hours of exposure to achieve a high mortality rate while the others required longer. By using the proper amounts of these products, the researchers hope to find the “sweet spot” that kills a substantial number of zebra mussels without affecting harmless non-invasive species, said Nicholas Phelps, the director of the

Klancke dock zebra monitor Sept 2021 - 1.jpg

The Klancke's on South Lakeshore Drive found zero mussels 2017-2019, 30  in 2020 and thousands this year as seen on these photos of a zebra mussel collecting plate they have had hanging on their dock since 2017.

University’s Minnesota Aquatic Invasive Species Research Center, which funded the study. In addition to testing the concentrations on zebra mussel veligers, the researchers tested those same concentrations on snails, four native fish species, one native mussel species, and Daphnia (water flea - a zooplankton species) to see how other species would respond to this type of treatment.

“This is the first time that we’ve really created a plan that people in Minnesota can actually put into action on their lakes to control zebra mussels,” said Christine Lee, communications specialist for MAISRC. By reducing the populations of zebra mussels, the researchers hope to mitigate the species‘ negative economic impact, which can total more than one billion dollars per year nationwide, according to the U.S. Department of State.

Link to an article about how to protect your boat:


Link to DNR’s page on zebra mussels:

Yellow Iris are invasive

by Tom Blanck


Last spring, my wife and I were kayaking in the channel behind Lindgren Lane. We came across a number of plants sporting beautiful yellow flowers growing right on the edge of the channel. They looked like irises and we thought someone must have gone to some trouble to plant these lovely flowers on the swampy shore. They were impressive!



Wrong! Turns out these beauties are an invasive species! Iris pseudacorus (Pale-Yellow Iris or Yellow Flag Iris) has escaped cultivation and now is spreading rapidly across parts of Minnesota. A native plant of Eurasia, it is a perennial, herbaceous, aquatic plant whose leaves and flowers grow above the water surface. It grows 2-3 feet tall along shorelines in shallow water. It forms very dense mats of rhizomes and crowds out native plant species.

The Yellow iris flower is 3 to 4 inches across with 3 large petal-like sepals that hang down and 3 smaller upright petals. The lower sepals have a ring of reddish brown flecks near the base and are beardless. There are a few flowers at the end of each stalk.


Fruit is an oblong, 3 angled capsule around 2 to 3 inches long and 1/3 to ½ as wide. Each 6-angled seed pod is about 2-4 inches long and can produce more than 100 seeds that start pale before turning dark brown. Each seed has a hard outer casing with a small air space underneath that allows the seeds to float. Yellow iris reproduces vegetatively through horizontal stems growing below the soil surface, called rhizomes, forming roots and producing new plants.


Yellow iris is poisonous to humans and animals if eaten, and its sap can cause skin irritation.

Small populations of yellow flag iris can be manually removed. Be sure to wear gloves and long sleeves, as the sap of the plant may cause skin irritation. All parts of the plants must be removed, especially the rhizomes. Cutting flower heads may help prevent the plants from spreading as quickly. Aquatic herbicides may be effective at controlling yellow flag iris, but typically herbicide use in aquatic environments requires a permit, so check with your local DNR office.


Here is a link to the MN DNR sire for more information:

July 23, 2021 AIS Monitoring Update

Lake Independence has know infestations of Eurasian watermilfoil, Curly-leaf Pondweed, and Zebra Mussels, all were found during our survey. Newest to our AIS list is Yellow Iris which we found last year for the first time. This year a large patch was noted by Kristen Blanck when she was kayaking near the Lindgren lane channel. Good news is we did not find any Starry Stonewart which has made appearances in other area lakes.

A big thanks to our hosts, Pat and Dick Wulff, for serving a delicious brats and sauerkraut lunch before we headed out on the water!


Craig Olson and Kristen Blanck pull in the first rake of aquatic plants to be surveyed.


Dick Wulff was our captain for the day. LICA members Craig Olson, Kristen Blanck, Pat Wulff and Barbara Zadeh went out on the water with limnologist Carolyn Dindorf from Fortin Consulting. 


A pitstop at the home of Bob and Annie Ibler on Lindgren Lane to look at the many zebra mussels they have found on their shoreline, mostly attached to these native clams.


Yellow Iris may be pretty but they are an invasive plant that chokes out native plants. Look for an update coming soon with information about this newest invasive.

2019 Survey Results:
Eurasian milfoil
Curly-leaf pondweed

    In the summer of 2019, LICA commissioned James Johnson of Freshwater Scientific Services to survey Lake Independence and identify the areas of the lake with the highest concentrations of Eurasian milfoil and curlyleaf pondweed. The curlyleaf pondweed survey was performed in late spring when the growth is peaking; the milfoil survey took place in the summer when the concentrations of milfoil are at their maximum. The data was collected by following a zig-zag course in the shallow areas all around the lakeshore. GPS readings were taken to pinpoint the exact location of each measurement.

    The purpose of the survey was to identify those areas where treatment would have maximum beneficial impact. But Johnson recommended to the Board that before we take any action, we develop an Aquatic Plant Management (APM) Plan that spells out our goals and objectives, to provide guidance when prioritizing future projects. There are a number of issues related to treatment plans: cost vs benefit, input from lakeshore owners, areas where treatment would be most effective, what type of herbicide to use, etc. Before drafting our APM plan, the LICA board will be surveying members for their input. We will also be working closely with experts from the U of M, DNR and Three Rivers.

Curly-leaf Pondweed


Potential Treatment Areas

Eurasian Milfoil


Potential Treatment Areas

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