22 Jun

New Discoveries in Swimmer’s Itch

Education, News No Response

Prevention is the Key

“An ounce of prevention is worth a pound of cure” so the saying goes.  This certainly rings true for Swimmer’s Itch. Prevention is the key to itch free enjoyment of our waters.

Listed below are suggested preventative strategies based on GLA Swimmer’s Itch research on the behavior and life cycle of Swimmer’s Itch. If carefully employed, these methods will work to greatly reduce the total number of or even eliminate itch cases for an entire swim season. Please note that these strategies should be used together to be most effective at preventing Swimmer’s Itch.

  • Cover your skin with swimwear that covers the area you want to be itch free (SI rarely affects a person’s hands, feet, and face)
  • Towel off vigorously after swimming
  • Swim in the afternoon or early evening vs. morning
  • Do not swim when the wind is blowing onshore.
  • Do not swim/wade in shallow water without using prevention measures
  • Install a swim baffle in your swim area (two years of research indicates this works!)
  • Use a parasite skimmer (watch the video link below for more info)
  • Use a kid friendly wading or “kiddy pool” vs. using shoreline lake water for small kids to swim more safely and itch free.

Be aware that there is never a case, even using all these tactics, that Swimmer’s Itch risk can be reduced to zero. But there is so much we can do to have our best chance at preventing the itch. Check out this informative Swimmer’s Itch Prevention Video on what we learned from our 2017-2019 research and for more details about what you can do! And if you do experience Swimmer’s Itch, please click here to report a caseWith your help, we can monitor and track cases of Swimmer’s Itch —and progress in managing it.

Brief tutorial and history of Swimmer’s Itch

Cercarial larva is the parasite that causes Swimmer’s Itch on Glen Lake. (NOTE: there are multiple species of parasites that cause Swimmer’s Itch in Michigan.) Cercariae are shed by multiple snail species that are infected by parasites transmitted by avian hosts —such as the Common Merganser, Canada Geese and Mallard ducks.

Historically we tried to break the lifecycle of the parasite in one of the two hosts. We tried to kill the snails by copper sulfate treatment, but that was ineffective (snails repopulated after expiration of the two hours of chemical potency). However, this was the only treatment for more than 30 years, from the 1950s to the 1980s. We tried to remove and harass the resident mergansers which at the time were thought to be the exclusive avian hosts on our lake from the 1980’s-2019. Despite these efforts, numbers of mergansers and cases of swimmer’s itch increased, and we discovered through DNA testing that mergansers were not the exclusive SI hosts we had once thought them to be.

Where are we now?

The Glen Lake Association has a 30-plus year effort in the research and management of Swimmer’s Itch. Our research in the mid-’80s helped define the life-cycle of Swimmer’s Itch on Glen Lake, i.e., one snail species and one bird species. Research from 2017-2019 again revolutionized the scientific understanding of Swimmer’s Itch. Through use of DNA testing, multiple species of itch were identified (including a never before discovered species) cycling through multiple bird hosts in addition to the Common Merganser, all contributing to Swimmer’s Itch on Glen Lake. Given what we now know, it is clear that attempts to control Swimmer’s Itch by interrupting this complex life cycle are ineffective.

Given the newly understood, increasingly complex nature of Swimmer’s Itch and clear and overwhelming evidence that copper sulfate application and Merganser harassment, trapping and relocation are ineffective and even harmful, what is there left to do? The Glen Lake Association has learned and continues to make new discoveries that lead us to new approaches for combatting Swimmer’s Itch. The key to future success in our treatment of Swimmer’s Itch is to prevent humans from coming into contact with the Cercarial larva. Using what we have learned about the behavior of Swimmer’s Itch, we can arm our ourselves against exposure to the Itch.


Prevention is the key! Research has demonstrated that there are methods and technologies available to effectively control individual swimmer exposure to Swimmer’s Itch. But we need your help! Ongoing research including the use of data from Swimmer’s Itch case reporting will be keys to furthering our ability to protect against and prevent Swimmer’s Itch.

Watch an informative video about SI here.



18 Jun

75th Celebration Fundraising Campaign: Supporting our Watershed Scientist Position

Education, News No Response

It’s all about the water….

After 75 years, the Glen Lake Association is celebrating this impressive milestone with the same basic focus: protecting and preserving the water within the Glen Lake/ Crystal River Watershed.

To commemorate this accomplishment with an eye to the future, the GLA Board of Directors is announcing the “75th Celebration Campaign” now underway.

Contributions raised between now and our Annual Meeting date of August 6 will finance GLA’s Watershed Scientist position, currently held by Watershed Biologist Rob Karner.

The association’s 75th Campaign goal: $150,000. Please click here to donate. 

Thanks to the generosity of three investors, the 75th Campaign has been challenged to raise $75,000 which they will match dollar-for-dollar, doubling the impact of every gift.

“Over seven decades of caring about our water by many people has brought us to where we are today,” said GLA development chair, Lori Lyman. “Through sound management practices, cutting-edge research and support by boards, staff, and a long list of volunteers committed to saving this resource, GLA is known throughout the state and beyond. Despite this strong leadership and progressive programming, the challenges continue with more invasive species, increased pressure and use and changing environmental conditions. To save this cherished water, GLA needs to remain vigilant in its research and education efforts.”

Please help us by investing in the future of the GLA during this landmark year. Your support will enable GLA to continue to research and deploy environmental best practices resulting in protecting and preserving the unparalleled Glen Lake/ Crystal River Watershed.

08 Jun

New Discoveries in Swimmer’s Itch

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It has been widely accepted by many Swimmer’s Itch scientists that once Common Mergansers (once thought to be the major player in Swimmer’s Itch on Glen Lake) were live trapped and ready for relocation, that the approved DNR relocation sites were “safe” places to set the trapped birds free. The Michigan Department of Natural Resources (DNR) approved relocation sites based on four principles:  

  • New area is not a good swim area;
  • Site is free of the snail species that carries the parasite that cycles through Common Mergansers;
  • Not a place where the DNR fisheries were planting fish;
  • Suitable for Common Merganser survival

The 2019 Swimmer’s Itch research has now confirmed that many of the relocation sites have been tested “positive” for the species of parasite that cycles through Common Mergansers! This is bad news for the Swimmer’s Itch control program because it likely means that relocating Glen Lake mergansers to relocation sites that already have the parasite will only increase—perhaps dramatically—the itch risk for swimmers near the relocation sites. This new discovery presents a new ethical dilemma for the GLA and other lake associations around the state that use live trapping strategies.

One would think that a simple solution to this dilemma would be to find new sites that meet the DNR criteria where the parasite is not present. This may be a solution, but in the opinion of the local experts, there are likely “no new sites” to be found. Also, new discoveries have shown that relocated mergansers travel up to 20 miles once they are set free. 

Old Assumptions, New Thinking

Just a few years ago, it was thought that almost all of itch-causing worms came from Common Mergansers, with other birds like Mallards and Canada Geese only minor contributors. It was standard thinking, therefore, to assume that removing Common Mergansers from Glen Lake would have a major impact on reducing itch risk.  

However, 2019’s research on Swimmer’s Itch shows that Mallards and Canada Geese contribute to the parasite load in percentages higher than imagined. The mix of Swimmer’s Itch parasites from all the birds collectively contributes to increasing itch risk.

New data also suggests that snail densities, which can directly impact itch risk, fluctuate significantly from year to year. For example, when certain species of snail densities are high and combined with high population densities of the bird host, then SI risk for that specific life cycle can be problematic in a given year and move to center stage while other life cycles either hold their own or diminish.  

What does this mean for Glen Lake and our lake-wide effort to control Swimmer’s Itch? One thing is certain, the life cycle that is dominant one year may play a minor role in the next year, depending on snail density fluctuations and changing bird populations. This is a complex issue, with Mother Nature throwing in all kinds of twists and turns that make lake-wide control not only difficult but perhaps unattainable.

GLA will continually update you with new information as we receive it.

04 Jun

GLA Pioneering New Study on Septics, Seeks Riparian Volunteers

Education, News No Response

The GLA has engaged Freshwater Solutions, LLC and the University of Alberta Canada to conduct a pioneering study on septic influences on our surface waters (lake) and drinking water (private drinking wells). 

Ordinarily, the county health department and/or the National Park Service is involved in monitoring public beaches on Glen Lake for E.coli and will close down beaches if E.coli exceeds safe levels for swimming. As in the same way with drinking water, the county health department is primarily responsible for testing home drinking wells, with the tests including E.coli, nitrates and other parameters.  



So why is GLA getting into research that health departments normally cover?  

The reason is centered around the advent of new technology that the health departments are not yet equipped to handle. The new technology involves quantitative polymerase chain reaction, or qPCR. With this new technology, we can detect and quantify the DNA of enteric bacteria that comes exclusively from septic systems.  

Our goal this summer is to choose 15 willing riparians on the shores of Big and Little Glen and test for enteric bacteria in the drinking water and the surface waters along the beach. There will be three sampling dates for each site. Samples will be taken during June, July, and August. If you are interested in gaining some peace of mind and are willing to be a part of this study, please contact Rob Karner, GLA’s watershed biologist, at his email:  

We will also combine water samples with septic drain field analysis and evaluation using drone technology and infrared cameras. We hope to be able to determine if drain field failure is detectable using thermal imagery.

If you are interested in being a part of this study, please contact us soon. There are limited spaces available for this unique, in-depth opportunity. Those who are selected to participate will be asked to contribute $250 each, to offset the total project cost of $8,900. For the cost of a regular septic inspection ($250) you could learn much more about your system and support the Glen Lake Association in conducting important research.

Note: Results of the study will be shared with the membership in a statistical manner that protects the privacy of individual participants. Individual results from each of the sampling sites will only be shared with each respective property owner in a confidential manner.

We look forward to your individual interest in this important study. Remember, failed septic systems are one of the leading causes of water quality degradation.  

Watch this video for more information on septic and well water protections: Road Map of Enteric Studies video.

18 May

Brooks Lake – Part 3 of Satellite Water Bodies in our Watershed

Education, News No Response

18 May

Guardian Ambassador Shares Info on Lake-Friendly Landscapes

Education, News No Response

GLA is continuing its mission—75 years and running—to preserve and protect the quality of water in the Glen Lake/Crystal River Watershed. One of the association’s newest initiatives is Glen Lake Guardians, which educates and advocates protecting our watershed by engaging in best practices. Guardians voluntarily pledge to protect, and share their advocacy with others.

Guardian Ambassador, Tricia Denton, below, is sharing information to  help lakeshore property owners create and maintain sediment and pollution “traps” along the shoreline. 

Vibrant strips of native vegetation along the shore are important contributors to water quality, helping to slow stormwater runoff and remove unwanted sediments. Native vegetation also provide long and deep root systems that help prevent erosion from shoreline ice build-up in winter. While these vegetative filter strips protect water quality, they are also important in improving habitat without blocking access to docks and the water.

Learn more by watching this video.

Currently, the Glen Lake Association is working with the Leelanau Conservancy and others to re-write and improve its Watershed Management Plan for review and approval by the Michigan Environment, Great Lakes and Energy (EGLE) Department. Watershed management plans organize and encourage efforts by watershed groups, local governments, and others to reduce and prevent pollution from entering lakes and streams throughout Michigan.

The conservancy’s program manager, Yarrow Brown, says the Leelanau Conservancy has a big stake in watershed planning and management and is happy to facilitate the development of plans with lake associations. After all, the conservancy is a leader in protecting land from degradation and preserving healthy ecosystems, including streams, lakes and wetlands.

Learn more about Glen Lake Guardians.

30 Apr

Day Mill Pond – Satellite Water Bodies in Our Watershed Part 2

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The 7-acre, 3-foot deep Day Mill Pond lies west of the west end of Little Glen Lake and is easily observed from M109 highway. Hydrologically, it is connected most of the time by a 3-foot diameter culvert and a small, slow-flowing creek that empties into Little Glen. Beaver have been known to plug up the culvert in an attempt to flood the pond and raise the water level.  

During the summer, the entire surface of the pond is choked off by the ever increasing number of pond lilies that have expanded over the past decade. Also, the shoreline is surrounded by an ever expanding population of cattails, which can be thought of as shoreline building plants. In time, the progressive growth of the cattails toward the center of the pond—building land behind them—will be complete and the pond will become a cattail swamp. Maybe in the next 40 to 50 years, if nature has her way, this pond will cease to exist!

Historically, the pond was better connected to Little Glen prior to the building of M109. The national park has in its long-range plans to replace the culvert with a box culvert and bridge that would go under the highway. An environmental assessment has been completed and the timetable for construction has yet to be set. Public hearings and financial backing would need to happen before any construction.

Because the pond is surrounded by National Park Service boundaries, there are no riparians on the pond and it is a haven for spring and fall migrants. Ring-necked Duck, Wood Duck, Ruddy Duck, scaup, mallards, geese, swans, grebes, American Coot, Green Herons, Sandhill Cranes, and even a common egret can be observed. The pond is also  the home of the less common Blandings turtle. In the spring, there are lots of migrating song birds— mostly warblers of all kinds that make this a special place in our watershed. Muskrats, raccoon, deer, mink, and beaver can be seen during the non-winter months.  

Now you can visit area lakes and ponds with a greater appreciation for their character and at the same time, be rewarded for what nature may have in store for your viewing pleasure.

27 Apr

Spotting the Invasive Coltsfoot

Education, News No Response

Coltsfoot, (Tussilago farfara) above, is the first invasive to watch out for around Glen Lake. When you see our native Marsh Marigold (Caltha palustris) blooming, it’s time to scrutinize your property for coltsfoot. The bloom period of these two plants typically coincides.


The Glen Lake Association needs help finding this invasive springtime plant.

Spot Coltsfoot by looking for yellow flowers, seen below, that emerge before the leaves and open on sunny days. The flowers are similar in appearance and size to a dandelion’s, but with the addition of leafy bracts along the stem. Later in the season, after the flowers have matured, Coltsfoot can be identified by thick, fleshy, heart-shaped leaves, up to eight inches long and wide. 

Coltsfoot first invades sunny, low-lying wet areas, but is very adaptable and if left uncontrolled can spread into bright, high and dry zones quickly. It can also grow, bloom and spread in shade, though with less vigor. If left uncontrolled, Coltsfoot has the potential to completely blanket a sunny spot, decreasing biodiversity along with your property value. It threatens to invade the same habitat of our precious endangered species, the Michigan Monkey flower. If it escapes the shores of Glen Lake, Coltsfoot threatens our surrounding agricultural communities. It has proven to be an agricultural pest in the US Northeast, Midwest and Pacific Northwest as well as in southern Canadian farmland.

Throughout the coming season GLA will offer timely tips on various invasive plants to watch for on your property. When you are away or are unable to personally survey your property, perhaps a neighbor or friend could help out in your absence. Informed gardeners or property managers could also perform surveys. 

Marsh Marigold typically blooms at the same time as Coltsfoot.

As a service of the GLA, your shoreline will be surveyed for Coltsfoot if it is in the region known or suspected to be infested around Big Glen. However, we welcome your assistance in surveying any property around both Big and Little Glen Lakes. The more eyes, the better!

If you spot Coltsfoot, contact Laurel Voran at
231-632-3211 or Tricia Denton at

For more information see this site.


20 Apr

Shoreline Erosion on Glen Lake

Education, News No Response

Click image to link to video.

The shorelines of Glen Lake are by nature’s design, an ever-changing phenomenon. Wind and waves during periodic storm events can peel away or build up shorelines into irregular and unpredictable patterns. This natural process can be troubling for riparians who desire to “keep it as it always was.” The GLA embraces the notion that natural shorelines are the best way to preserve water quality.

The results of our 2019 shoreline survey indicate that of the 17 miles of shoreline around Big and Little Glen, 1.8 miles of shoreline have rock walls, making up 10.4% of the total. Our survey shows that 94 riparians have chosen to harden their shoreline to prevent erosion. There seems to be a growing number of riparians who are choosing rock walls.  

Artificial rock shorelines can often be the last resort for riparians to control erosion. However, other alternatives can and should be considered, some which are more “lake-friendly.”

The use of coir logs is considered a great alternative to installing rock walls. Before making plans to install a rock wall, consider coir log installations as another good solution to battle erosion. The practice is relatively new to Glen Lake riparians and only a select few contractors have the experience to perform a successful installation. Coir log installations may not be for everyone but they are well worth the time to consider.

For more information about shoreline erosion control, click here.

We welcome your questions and interest if you are thinking of solutions to shoreline erosion. 
Contact us at 231-334-7645 or by email to

06 Apr

GLA is Online Webinar Sponsor

Education, News No Response

GLA is pleased to announce that we are the online webinar sponsor for the 54th Annual Michigan Lakes and Streams Association Conference that was to be held this May at Crystal Mountain Resort. That event has been cancelled but the MLSA is offering free webinars featuring speakers and presentations from the conference every Friday for the next seven weeks. GLA is the exclusive sponsor of this series! 

Here’s the link for the first episode which aired last Friday on the Shoreland Stewards program. GLA is acknowledged several times during the program. You can see slides highlighting GLA participation in the Shoreland Stewardship Program (GLA is top in the state!) at around 51:30.  GLA’s Guardian Ambassador, Tricia Denton, speaks at 1:01:33.

Future episodes can be found on the MLSA website. Enjoy some good lake and stream education right from your couch!