Zebra Mussel Information and Updates

Parks Canada has engaged with stakeholders, Indigenous partners, and the public as part of the decision-making process for how best to manage water activities in Clear Lake in 2025. It has become clear that Parks Canada does not have comprehensive scientific information about how motorized vessels may influence the spread of zebra mussels in Clear Lake. Protecting national park ecosystems is Parks Canada's highest priority, so Parks Canada is only allowing non-motorized watercraft to reduce the risk of transferring aquatic invasive species between waterbodies while it initiates a robust monitoring program and scientific study.

However, the decision also means that visitors will be able to resume many of the water-related activities they enjoy this summer. All watercraft, fishing equipment, wetsuits, and inflatables must complete a Parks Canada aquatic invasive species inspection and comply with Clean, Drain, Dry protocol.

Parks Canada has decided to continue to restrict the use of motorized watercraft on Clear Lake to reduce the rate of spread of AIS through water intakes and bilges. Protecting national park ecosystems is Parks Canada's highest priority, so Parks Canada is only allowing non-motorized watercraft to reduce the risk of transferring aquatic invasive species throughout Clear Lake itself, and between waterbodies, while it initiates a robust monitoring program and scientific study.

This approach is a continuation of Parks Canada’s attempts to reduce zebra mussel spread in Clear Lake and the potential damage that may be caused to downstream waterbodies and related infrastructure.

Parks Canada decision makers rely on robust scientific evidence, and it has become clear there is insufficient data about how motorized vessels will impact the spread of zebra mussels in Clear Lake. Protecting national park ecosystems is Parks Canada's highest priority, so the decision has been made to only allowing non-motorized watercraft in the park to reduce the risk of transferring aquatic invasive species throughout Clear Lake itself, and between waterbodies, while it initiates a robust monitoring program and scientific study.

Working in partnership with others, including Keeseekoowenin Ojibway First Nation and local stakeholders, in 2025, Parks Canada will initiate a comprehensive research study to understand the ecological and socio-economic impacts of motorized watercraft use in Riding Mountain National Park, including the IR 61A section of Clear Lake.

The key principle behind "one boat, one lake" is that it minimizes the movement of invasive species from lake to lake. Aquatic invasive species can be transported through water on boats, trailers, or even in mud on the equipment. If people are committed to using their boats only on one water body, it reduces the risk of transporting invasive species.

As part of broader aquatic invasive species prevention efforts, this program also stresses the importance of boat inspections and following Clean, Drain, Dry principles. This includes draining all water, removing mud and vegetation, and drying the watercraft and all related equipment thoroughly between launches.

Each year, thousands of visitors paddle, fish, and swim in the park's lakes and rivers. Parks Canada understands this change is disappointing to some, especially those who complied with mandatory inspections and tagging in previous years. Parks Canada is implementing these changes in an effort to continue protecting Clear Lake so that its health and those of downstream waterbodies can be maintained and visitors and residents can continue to enjoy them in the future.

The closure of Clear Lake to all watercraft last summer drew negative reactions from some business owners and residents. There were concerns expressed that visitation and revenues would be significantly reduced. With levels exceeding those of 2023, 2024 marked the busiest year for Riding Mountain National Park in the previous five years. Riding Mountain National Park is pleased visitors are choosing to spend time at the park and looks forward to welcoming more visitors during the 2025 season.

A review of data in the fall of 2024, with input from Indigenous advisors, the Province of Manitoba, and leading scientific and international experts determined that eradication of zebra mussels from Clear Lake is no longer an achievable option.

Eradication requires that the full population be identified, fully isolated and contained from the rest of the lake. There was significant time and effort spent trying to find a population cluster, as well as preparing for eradication attempts if such a population was found.

Although an attempt was made to isolate an area of the lake where eDNA had indicated the presence of a potential colony, additional data gathered in 2024 demonstrated that zebra mussels are much more spread out in the lake than initially thought, and the full extent of the zebra population is not yet known. Parks Canada has taken action based on the best data available at any given moment since the first discovery of zebra mussel eDNA in the lake.

At the end of the boating season, zebra mussels were detected at numerous, widespread locations in the east end of the lake. Based on size, growth rates and numbers found, establishment likely occurred earlier in the summer, before the curtain was installed. Even if the curtain had held up, zebra mussels would not have been fully contained and eradication would not have been successful.

The containment attempt was based on the best available information and was initiated in the area with the highest potential for zebra mussel establishment. The failure of the curtain was something that demonstrated the limits to using this approach to isolate sections of large, open bodies of water.

Understanding why high rates of eDNA were detected in Boat Cove and lower rates of eDNA were detected where other living populations of zebra mussels have since been found requires further analysis.

Over time, zebra mussels are likely to spread throughout Clear Lake and downstream. Although veligers cannot actively "swim", they will be spread by natural currents (e.g. thermal cycling, wind driven, and gravity). Zebra mussels are likely to negatively impact the existing ecology of Clear Lake by altering food chains, water quality and aquatic habitats. There may be a greater risk for toxic blue-green algae blooms which pose increased risks to visitor safety.

Zebra mussel veligers float through lake and river currents until they settle on a solid surface. Although they are likely to spread downstream through the outlet of Clear Lake, via Wasamin Creek (Clear Creek), down through the Little Saskatchewan and Assiniboine River Systems, it is currently unknown exactly how far they may travel and whether they will reach suitable habitat to settle and reproduce.

Aquatic invasive species monitoring will continue and will be focused on the spread of zebra mussels throughout the western portion of Clear Lake. There will be an increase in monitoring and sampling at outlying lakes such as Moon Lake, Grayling Lake, Whirlpool Lake, Lake Katherine, Lake Audy, and Deep Lake. Ensuring that zebra mussels are not spread to other lakes in the surrounding area will be considered imperative.

Parks Canada will monitor infrastructure throughout Clear Lake and assess management options while evaluating the establishment of the zebra mussels. There are no immediate concerns about the implications for water treatment infrastructure. Park staff will monitor this infrastructure and water quality and will continue to provide potable water into the future.

If evidence of zebra mussels is found in another waterbody in Riding Mountain National Park, Parks Canada will take similar steps to further investigate and assess potential containment and eradication options.