
Zebra Mussel Information and Updates
Riding Mountain National Park
NEW In 2025, Parks Canada will permit only non-motorized watercraft on Clear Lake and outlying waterbodies.
Watercraft Management 2025
Parks Canada has made the difficult decision to continue to restrict the use of motorized watercraft on Clear Lake in 2025. 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. This action means Parks Canada will permit only non-motorized watercraft on Clear Lake in 2025. Aquatic Invasive Species Prevention Program
Parks Canada is taking a precautionary approach in an effort to reduce the rate of spread of zebra mussels thereby continuing to protect the health of Clear Lake and outlying waterbodies in Riding Mountain National Park and downstream water courses so that visitors and residents can continue to enjoy them in the future. In the coming year, Parks Canada will initiate a comprehensive research approach to determine how motorized watercraft affect ecological, socioeconomic and cultural components of Clear Lake. Parks Canada appreciates visitor engagement and recognizes the important place Clear Lake holds in their hearts. Similarly, we greatly respect the strong connections that Indigenous communities and residents, both permanently and seasonally, have with Clear Lake.
Parks Canada takes their role to protect the health of Clear Lake seriously. This is why Parks Canada is taking this approach to aquatic invasive species risk reduction to protect all waterbodies in Riding Mountain National Park while ensuring lake users can resume many of the activities they missed in 2024.
What we heard – Questionnaire and Engagement winter 2025
Below is a summary of what we heard, for more information please contact comms-riding@pc.gc.ca
Parks Canada ran a public engagement questionnaire from January 28 to February 28, 2025, to inform the management of Clear Lake’s aquatic invasive species program for 2025. It received 2934 responses. 1232 respondents (42%) “own a motorized watercraft for use in Riding Mountain National Park,” and 1136 (39%) “do not use motorized watercraft in Riding Mountain National Park.” For comparison, 806 boats were registered in the tagging program in 2023, and Riding Mountain visitation was 338,490 in 2023-24.



During the Winter Adventure Weekend, February 1 to 2, 2025, the Field Unit Superintendent, management, and other staff also engaged in informal conversations with 268 local stakeholders. Visitors expressed polarized views:
- support for motorized boats on Clear Lake
- significant emphasis on protecting other lakes (including support for continued restrictions)
- pleasant surprise that restrictions were being lifted
- appreciation for the opportunity to be heard
- logistical questions
- questions about zebra mussels
- regret that zebra mussels have established in Clear Lake
There were 1092 survey responses, with strongly felt and polarized views.
There was very strong support for the “one lake, one boat” concept. Several respondents described how their boat had never been on another lake. Many supported the return of the 2023 inspection and tagging program. There was strong support for the return of the Martese commercial boat tour.
Key aquatic invasive species program suggestions:
- marina (similar to Waskesiu) and return of the boat ‘graveyard’ for seasonal mooring
- beach inspection stations for water toys and equipment, especially at Deep Bay
- wash or decontamination station available after hours and at outlying sites
- improved traffic flow around the Boat Cove to ensure access to cabins and townsite
Many respondents were concerned about enforcing restrictions for non-motorized watercraft, which do not require a boat launch.
Many commenters wanted no motors on Clear Lake, citing the Canada National Parks Act and Parks Canada norms, concern about transferring zebra mussels to other water bodies, the importance of First Nations consultation, improved enjoyment, and environmental impact. Several described examples of motorboats causing danger to swimmers and paddlers. Some asked for expanded restriction zones around swimming beaches. A number, including those who supported and owned motorized watercraft, were against wake boats or asked for a limit on motor size.
Many supported fees, especially if these are used to improve boat infrastructure. Some wanted per-use fee options, but others believed these would slow down the launch process and conflict with the ‘one boat, one lake’ concept. Many were against fees because they felt they already paid enough through taxes or park passes.
Respondents described long family traditions of boating on the lake, with both love and stewardship for this special place. A number cited accessibility – they cannot use non-motorized watercraft because of age or disability. Some were against time or area restrictions because boating depends on weather conditions, fishing is best in the early morning and late evening, and concern about creating dangerous congestion. Some wanted Parks Canada to drop all restrictions because they believed aquatic invasive species are inevitable.
Several commenters described motorboats as important for the local economy. Others believed motor restrictions would not impact tourism because most visitors do not own boats, and other users would replace the boaters if they left.
A number found the survey questions confusing or biased, both for and against motorized watercraft. Some expressed anger about their perception of mismanagement and poor communication in 2024, particularly around the containment curtain and eradication attempt. Others expressed appreciation for Parks Canada’s work in a difficult situation.
Zebra Mussel Response 2024
In fall 2024, Parks Canada staff found hundreds of live juvenile zebra mussels attached to docks and infrastructure near the east end of Clear Lake. This indicated that zebra mussels are not isolated to the Boat Cove area of the lake, where they had previously been found and where the containment curtain had been installed. With input and advice from Indigenous advisors, the Province of Manitoba, and leading scientific and international experts, Parks Canada has determined that eradicating zebra mussels from Clear Lake in Riding Mountain National Park is not feasible.
What are Zebra Mussels?
Zebra mussels (Dreissena polymorpha) are native to eastern Europe. They were first detected in North America in the Great Lakes in the mid-1980s. Since then, they have infested many waterbodies in eastern North America. They were first detected in Manitoba in 2013 when they were discovered in the south basin of Lake Winnipeg. They later also colonized the Red River from the US border to Lake Winnipeg. Since then, they have invaded the Nelson River from Lake Winnipeg to Hudson Bay, as well as Cedar Lake and Lake Manitoba.
Biology
Zebra mussels are freshwater hinged mollusks. They are filter feeders that attach themselves to solid surfaces. They breed very quickly, as females can release up to one million eggs each breeding season. After the eggs are fertilized, larvae (called veligers) emerge and are free-floating for up to a month. The larvae are microscopic and do not swim. Veligers float through lake and river currents until they settle on a solid surface. This natural dispersal method means they can easily affect waterways downstream from an invaded area. Zebra mussels have few, if any, natural predators in North America. As a result, they often permanently alter the food web and ecosystems they invade.
Negative impacts on people include:

- Increased maintenance costs
- Damage to equipment such as boats, hydro-electric generating facilities, water intakes, and other infrastructure along infested water bodies
- Injury from sharp shells
- Potential negative health impacts resulting from increased likelihood of toxic algae blooms
Negative impacts on aquatic ecosystems:

- Altering the food web by out-competing native species, like native mussels and other small invertebrates, for food (plankton)
- Removing large amounts of non-toxic algae (plankton) from the water and leaving behind toxic algae (cyanobacteria) to thrive, causing toxic algae blooms
- Affecting fish spawning areas by changing the surfaces of rocks and vegetation, impacting the survival of fish eggs
- Creating clearer water, allowing sunlight to penetrate deeper and changing the habitat by increasing the growth of submerged aquatic vegetation
Zebra mussels are especially harmful to native mussels, many of which are species at risk. They outcompete these species for food and will attach themselves to native mussels, suffocating them.
An infestation of zebra mussels in Clear Lake presents a real threat of significant and irreversible damage to the lake and downstream waterbodies.
Aquatic Invasive Species Prevention Program Timeline of Events
Summer 2011 – Monitoring for AIS, specifically zebra mussels, in Clear Lake begins.
Summer 2015 – Mandatory Parks Canada AIS inspections and decontaminations begin at Riding Mountain National Park.
Summer 2011 to 2023 – Water samples from Clear Lake and surrounding water bodies are taken and tested for zebra mussel eDNA.
January 2023 – Parks Canada is informed by Fisheries and Oceans Canada of a positive test result for zebra mussel eDNA in a water sample taken at an area known as Boat Cove, in Clear Lake on August 4, 2022.
May 4, 2023 – Parks Canada announces that trailered watercraft intended for use on Clear Lake must not have been in any other waterbody in 2023 and must undergo an inspection by June 15. Boats that met the requirements had a tag installed that sealed the boat to the trailer. This tag ensured that the watercraft had not been in another waterbody and posed no risk of bringing in aquatic invasive species. If this tag was removed or tampered with, the boat would not be allowed to launch in Clear Lake for the remainer of the 2023 season. All human-propelled vessels (canoes, kayaks, stand-up paddle boards) were required to undergo a Parks Canada AIS inspection, and if needed, decontamination before launching in park waters.
November 10, 2023 – Parks Canada officials do a physical search at Boat Cove and a clump of 48 live zebra mussels was found and removed from the water. Before that, zebra mussels had never been found in Riding Mountain National Park.
May 2024 – Parks Canada implements watercraft management measures that restricted all recreational watercraft use on Clear Lake for the time required to determine if a population of zebra mussels had been established and for any potential remediation. With exceptions for emergency vessels, the commercial tour boat The Martese, and one vessel from the Keeseekoowenin Ojibway First Nation.
August 2024 – Parks Canada closes the Boat Cove for the construction and installation of an impermeable containment curtain in Clear Lake. The curtain was installed in an area of the lake where living zebra mussels were found in November 2023 and July 2024. Shortly after installation, the curtain was damaged and was no longer an effective means of containment and would be removed. The curtain could not be repaired or replaced.
September 2024 - Parks Canada found hundreds of living juvenile zebra mussels attached to docks and infrastructure near the east end of Clear Lake.
October to December 2024 - Extensive internal and external review of the evidence and data collected from Clear Lake in 2024.
Questions and Answers
2025 Watercraft Management Decision
In January, Parks Canada shared a planned AIS prevention program for Riding Mountain National Park that would be similar to the one implemented in 2023. Why is it changing?
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.
Why is Parks Canada only permitting non-motorized watercraft in Riding Mountain National Park?
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.
What factors played a role in the decision to only permit non-motorized watercraft?
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.
Is a "one boat, one lake" prevention program considered a best practice for addressing aquatic invasive species?
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.
Did Parks Canada take into consideration the potential loss of tourism revenue to the community?
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.
Year | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Visitors | 347,418 | 338,882 | 334,025 | 358,803 | 304,574 | 352,291 | 356,722 | 420,105 | 355,816 | 339,441 |
2024 Zebra Mussel Response
Why has Parks Canada decided not to pursue eradication of zebra mussels in Clear Lake?
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.
Did the malfunction of the containment curtain play a role in the decision not to attempt eradication?
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.
What will happen to Clear Lake going forward?
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.
What does this mean for communities downstream?
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.
Will zebra mussel research and monitoring continue in Riding Mountain National Park?
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.
How will Parks Canada manage the impacts of the zebra mussel invasion in Clear Lake?
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.
What plans does Parks Canada have if zebra mussel eDNA is detected in an outlying body of water ie. Moon Lake?
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.
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