WI Lakes.net 2026 AIS Briefing

Aquatic invasive species (AIS) continue to pose some of the most significant ecological and economic threats to inland lakes across the Upper Midwest. With their ability to outcompete native species, disrupt food webs, damage habitat, and impair recreation, staying informed is essential for lake associations, anglers, paddlers, and waterfront property owners.

This 2026 update highlights key AIS concerns for Wisconsin—our primary focus—and provides a look at emerging and ongoing threats in Minnesota, Michigan, and Illinois. The annual cost to combat AIS in WI is expected to push beyond $13M given past costs. This reflects cost to combat and not necessarily the true ecological impact (displaced species, lost opportunity, disrupted cycles, etc).

This figure reflects statewide investments that include:

  • Monitoring and early detection
  • Watercraft inspection and decontamination
  • Local lake grants and rapid response funding
  • Enforcement of AIS transport laws
  • Outreach and education programs

AIS in Wisconsin: Current Species of Concern

Wisconsin’s Department of Natural Resources continues active AIS monitoring across the state’s waterbodies. Citizen monitors and partners play a central role in discovering new infestations and tracking established species. Many of these species fall under Wisconsin’s NR 40 invasive species rule, which classifies harmful plants, animals, algae, and pathogens. [dnr.wisconsin.gov]

Most Prevalent Aquatic Invasive Plants in Wisconsin

The following AIS plants remain widespread concerns, frequently appearing in verified waterbody lists across the state: [apps.dnr.wi.gov]

  • Eurasian Watermilfoil (Myriophyllum spicatum)
    Forms dense mats, inhibits boating, and crowds out native plants.
  • Curly-Leaf Pondweed (Potamogeton crispus)
    Early-season growth shades natives; sharp die-offs degrade water quality.
  • Purple Loosestrife (Lythrum salicaria)
    A wetland invader that displaces native vegetation and reduces habitat value.
  • Brittle Waternymph (Najas minor)
    A fast-spreading submerged annual found in many southern and central Wisconsin lakes.
  • Starry Stonewort (Nitellopsis obtusa)
    An invasive alga forming dense, star-shaped bulbils; increasingly detected in Wisconsin. [storage.go…leapis.com]

    High‑Risk or Restricted AIS Plants Under NR 40

    The state identifies additional prohibited or restricted species that require rapid response if detected:
    Hydrilla, Brazilian Waterweed, European Frog-bit, Parrot Feather, Yellow Floating Heart, Water Chestnut, and others. [storage.go…leapis.com]

    Aquatic Invasive Animals of Concern in Wisconsin

    Key faunal invaders documented across Wisconsin waterbodies include: [apps.dnr.wi.gov]

    • Zebra Mussels (Dreissena polymorpha) – Sharp-shelled filter feeders that alter water clarity and ecological balance.
    • Chinese & Banded Mystery Snails – Compete with native snails and degrade beach quality.
    • Rusty Crayfish (Faxonius rusticus) – Aggressively displaces native crayfish; destroys aquatic plant beds.
    • Invasive fish concerns, including introductions of Round Goby and Carp species, remain regionally relevant.

    How Wisconsin Manages AIS

    Wisconsin’s AIS strategy includes rapid detection, NR 40 enforcement, educational outreach, and lake-by-lake management permits for plant control. Citizens can report sightings via the DNR’s online reporting tool.

    Minnesota: Rising AIS Challenges and Notable Trends

    Minnesota remains a national hotspot for AIS research and early detection thanks to the Minnesota Aquatic Invasive Species Research Center (MAISRC) and the Minnesota DNR.

    Key Minnesota AIS Issues

    • Zebra Mussels: Widespread; recent studies link their presence to elevated mercury levels in fish, raising human health concerns. [lakeindependence.org]
    • Prohibited Invasive Species Expansion: Minnesota DNR recently classified 13 high‑risk AIS as prohibited to prevent introduction and spread. [invasivesp…esinfo.gov]
    • Invasive Carp Management: The state continues aggressive prevention efforts to keep carp species from expanding into northern lakes and rivers.

    Minnesota Monitoring and Data

    Minnesota maintains a continually updated AIS database covering occurrences of invasive plants, fish, invertebrates, and diseases. [mnatlas.org]


    Michigan: Watch Lists, Plant Threats, and Early Detection Priorities

    Michigan’s program emphasizes early detection and rapid response, supported by extensive watch lists and detection campaigns.

    Michigan Watch List Aquatic Invasive Species

    Michigan has designated 18 aquatic invasive species as high-risk, including:

    • 10 aquatic plants
    • 5 fish species
    • 2 crayfish species
    • New Zealand Mudsnail
      Efforts include public reporting via MISIN and statewide BioBlitz events. [michiganfarmnews.com]

    Notable Aquatic Plant Threats in Michigan

    Michigan’s watch list and field guides highlight plants with limited distribution but high invasion potential, including:
    Brazilian Elodea, European Frog-bit, Hydrilla, Water Chestnut, Yellow Floating Heart, Parrot Feather, and others. [lssu.edu]

    Statewide Program Focus

    Michigan’s inter-agency Invasive Species Program addresses species that threaten local ecosystems, focusing on early detection and rapid response to prevent establishment. [michigan.gov]


    Illinois: Key AIS Concerns in the Great Lakes and Statewide

    Illinois is a critical geographic link between the Mississippi River system and the Great Lakes, making it a priority region for invasive carp prevention and aquatic species management.

    Major Aquatic Invasives in Illinois

    Illinois Extension highlights several unregulated yet concerning AIS, including:
    Flowering Rush, Hydrilla, Brazilian Egeria, Purple Loosestrife, Eurasian Watermilfoil, Curly-Leaf Pondweed, Spiny Water Flea, Zebra Mussel, Asian Carp, Round Goby, Chestnut Lamprey. [extension….linois.edu]

    Invasive Carp Threat in Illinois River System

    The state remains a frontline defender against invasive carp entering the Great Lakes.
    A 2025 field study highlights ongoing monitoring of exploding Silver Carp populations and measures to prevent movement toward Lake Michigan. [chicago.suntimes.com]

    Statewide Coordination

    Illinois’ Wildlife Action Plan includes a comprehensive Invasive Species Campaign focusing on prevention, early detection, and interagency collaboration. [dnr.illinois.gov]


    Why AIS Management Matters for Wisconsin Lakes

    Wisconsin’s lake health—water clarity, habitat structure, fishing quality, and recreational value—depends on persistent vigilance. Neighboring states face similar threats, and regional collaboration has never been more important.

    How You Can Help

    • Inspect boats and gear: Follow Wisconsin’s “No Transport” law to remove all plants, animals, and mud.
    • Report sightings immediately: Wisconsin DNR’s reporting portal enables quick verification.
    • Volunteer for monitoring: Local lake associations and Water Action Volunteers welcome community scientists.
    • Stay informed: Many AIS now spread through gear, aquarium releases, and hitchhiking in bait and plant fragments.

    Conclusion

    Aquatic invasive species remain a dynamic challenge across the Upper Midwest, with Wisconsin at the center of coordinated regional efforts. By understanding which species pose the greatest risk—and by learning from neighboring states’ battles—we can better protect the lakes we love.

    If you’d like, I can turn this into a formatted PDF, add images, or adapt it for social media or newsletter distribution.

    Exploring Hot Lake Topics for 2026

    Over the course of the next year, Wisconsin Lakes will look to explore our changing world of lakes. Here are five high-impact blog topics that we look to explore here at WisconsinLakes.net that are relevant to lake associations, property owners, and districts:


    1. Wake-Enhanced Boating: Balancing Recreation and Lake Health

    • Why it matters: Wake boats and ballast systems are a growing concern in Wisconsin and lake communities in general. They can damage shorelines, uproot aquatic plants, and disturb fish habitats.
    • Goal: Work to explain the ecological impacts, summarize proposed statewide regulations (e.g., distance from shore, recommended depth), and offer practical tips for lake associations to manage wake sports locally.

    2. Combatting Aquatic Invasive Species (AIS): Prevention and Rapid Response

    • Why it matters: AIS like Eurasian watermilfoil and zebra mussels threaten biodiversity and property values. Starry Stonewart is a newly identified threat in WI.
    • Goal: Share best practices for prevention (boat cleaning, ballast tank decontamination), highlight new DNR initiatives, and showcase success stories from Wisconsin lake districts.

    3. Climate Change and Wisconsin Lakes: What Local Data Shows

    • Why it matters: Longer ice-free seasons, warmer water, and nutrient loading are changing lake dynamics. As previously touched upon we will reopen this topic based on emerging data.
    • Goal: Use Citizen Lake Monitoring Network data to illustrate trends in water clarity, temperature, and algal blooms. Offer adaptive management strategies for lake associations to consider.

    4. Shoreline Management and Erosion Control for Property Owners

    • Why it matters: Poor shoreline practices accelerate erosion, degrade water quality, and reduce property value.
    • Goal: Provide actionable guidance on buffer zones, native plantings, and ordinances. Include links to model regulations and funding opportunities for restoration projects through possible cost share.

    5. Forming and Strengthening Lake Associations: Governance and Funding

    • Why it matters: Strong associations are key to sustainable lake management and property value protection.
    • Goal: Outline steps to create or revitalize a lake association, explain statutory powers under Wisconsin Chapter 33, and share tips for securing grants and building community engagement.

    Climate Change and Your Lake

    The change appears to be slow. In fact, it may not even appear to be noticeable. What are even the signs? Wisconsin and the Midwest are home to a wide variety of lakes, all of which may be impacted in different ways. In addition, management of lake issues has been an evolving practice since its inception, so adding contingency to a wrinkle for an imperfect science only makes things more complicated for stakeholders with controlled budgets. Wisconsinlakes.net has not yet seen a good guide or resource page that provides any real guidance surrounding the issue of climate change, most likely because to the naked eye it may appear to be normal issues continuing to manifest themselves, albeit in an accelerated or different manner. We hope the information within this posting proves beneficial to some. None of this is backed by research or academic sourcing. It is observational and is not universally applicable.

    To continue this in this post discussion, it must be understood that climate change is a real thing, not a made up concept from 1987. Most have accepted this by now. In fact climate change is being referred to as “climate shift” by many in the sense that climate is not simply changing but, but causing a physical shift of range of changes. Regardless of how you wish to catalog these changes internally, they are in fact a real thing and will likely require solutions based on adaptability and proactive maintenance rather than a fixed endgame solution.

    While coarse policy begins to take shape both nationally and globally, communities are faced with real world issues that impact people at the local scale, both economically and from a health and safety perspective. There are endless miles of utility infrastructure beneath the grounds surface, all of which are at some degree of risk. There are no fast and ready rules to apply because each of these communities geographical space is unique. Some face coastal concerns, some flooding, and yet some seismic. The geographical space and unique weather patterns all require custom approaches. Even more so with lakes. Lake types can differ greatly simply by being a few miles apart and will therefore act differently due to precipitation, landscape positions, watershed size, urban influence, temperature flux, and other factors both known and unknown.

    The term resiliency is often used to describe the process of making something able to withstand or adapt to change. There is also a general school of thought that believes that natural systems are generally more resilient than manufactured systems. Often potentially overlooked in this equation is general systems maintenance. Do systems lack resilience or do they generally lack maintenance? These can be difficult questions to answer. Even more importantly is the need to consider the tracking of assets for those same maintenance reasons.

    So how does all of this factor into a discussion about our lakes, climate change, and the quest for resiliency? Below is a list of potential considerations for your lake that can be potentially influenced by climate change:

    Shorelines: Several of the topics below have a degree of interplay, that is they do not operate independent of each other but each may influence each other. Shorelines can be impacted by water level and system volume, among other things. Vegetative systems that make up shorelines adapt to water levels but take decades to adjust since ecological systems react over time. Waves and ice add a dynamic, but these are still natural occurrences, whereas wakes are not.

    As climate reduces months of ice cover in Wisconsin, that is traded for more precipitation as rainfall. Additional months of rainfall throughout the Midwest can result in higher groundwater levels or longer periods of drawdown at dams and outlet structures. Elongated periods of high water put natural systems at risk as they can be exposed to extended periods of inundation, wave impact and even record high wake impacts. Several river systems in WI and throughout the midwest have shown signs of higher than average baseflow. Higher baseflow results in necessary shoreline adjustment, albeit incremental over time.

    Water elevation will be discussed further below, but sustained high water exposes shoreline not traditionally adapted to water inundation. Saturated soils may leach fines (smaller soil particles) and girdle vegetation roots, increasing the mortality of plants and increasing erosion or lateral loss of land.

    Reinforced shorelines are not absolute solutions. Man-made systems can be compromised by repeated overtopping, toe scour, or improper design. Research also suggests that hard armor shoreline reflects wave activity along adjacent unprotected shorelines and can have ecological impacts. These effects can have cumulative effects in urbanizing lake environment. Shoreline solutions will need to flexible rather than simplistic. Good solutions typically suggest bio-engineered shores capable of withstanding wave and wake punishment, but also regrowth of vegetation when possible.

    Sediment: 10/7/2023

    Water Level: TBA

    System Volume: TBA

    Infrastructure: TBA

    Lake Ecosystem: TBA

    Nutrients: TBA

    Our Second Love, Our Lakes

    On this Labor Day I hope most are getting the opportunity to get out onto their lakes to enjoy a wonderful day in the upper midwest. As the boating season begins to wind down and the leaves begin their annual color change we can reflect back and the summer that to many may seem like it never was. The Great Outdoors to many others has proven to be an excellent distraction to a world in apparent disarray. For some of us who have spent more time than usual out on the water it may have provided greater insight into the value of our surface waters; this includes public waters of the state, rivers for example for kayaking/canoeing, etc.

    What have we seen? Have we accumulated any new knowledge that has helped us become better stewards of the waters? Have we observed something new that has led us back to our home office to investigate the question on the internet? Have we shared information or questions with others? If our waters our something we truly cherish it takes more than a passive interest to preserve it.

    The diversity of lake users is greater today than it has ever been. This includes users of varying backgrounds with variable agendas. These agendas may not always be be in unison with the best interests to the waters we inhabit, but we can all hope to play in this sandbox in harmony. If our waters spoil well then the party is over. Our water resources do not have a hospital they can got to when they feel sick or are becoming undone. We are sickness but also the cure.

    This is a good time to sit back, enjoy the weather and reflect back on the things we can do better on with our lakes. What have turned a blind eye to for too long. Fall brings time to contemplate these things and plan for the winter and upcoming year. Start taking stock in the little things and track lake progress.

    Up Next, we’ll take a look at the process of video recording your shoreline.

    Quick Primer on Grants

    As noted a few posts ago, grant season is among us. It is very common that lake districts, improvement associations, and individual property owners seek out funding assistance for a wide variety of projects that can help improve conditions within lakes, wetlands, and streams for water quality, navigation, flood control, and aesthetic appeal among other things. The one thing that grants however do not consistently funding is dredging projects.

    Why is that someone might ask? The simple answer, although it never appears to be a simple answer from the regulatory end, is that dredging is often categorized as a maintenance item. While it can certainly be debated on both sides the fact stands in most cases dredging does not have a taxpayer based funding mechanism.

    In a sense it is understandable that a process that is so heavily driven by healthy watershed practices be addressed at that level; and furthermore the necessity to appropriately and proactively consider the implications of sediment delivery mechanisms before addressing in lake issues. Grants can be obtained for this. It becomes a simple discussion of addressing a symptom and not the cause. Dredging is a snapshot in time, in which that snapshot begins to deteriorate the moment the contractor leaves the site. The rate of deterioration is further dictated by the practices in place on the ground to combat runoff and sedimentation. Most agencies would rather see money put towards these practices to address the issue at the point of attack rather than once the material is in the water.

    So facilitating the cost of dredging is a tricky situation. Good consultation can often help in mitigating or controlling costs, but it often estimated that the cost to remove sediment from the water is nearly 6X the cost it is to attack it on land. Pair this with the fact that so many view dredging as some “big fix” when it is really only a temporary reprieve. There is money available for better shoreline practices, buffer establishment, runoff control practices, and land preservation/protection. The State of WI sees this as the better immediate value and they are not alone in this perspective.