When you imagine a perfect summer day on Lake Windermere or Columbia Lake, you might picture sparkling water, sunshine, and boats cruising by. But beneath the surface — literally — these beloved lakes are feeling the strain of growing boating activity.
Two lakes, one problem
Watching boats slice through the water, the visual impact appears as a simple billow of white trailing behind the watercraft as waves push towards the shore then break and recede back into calm waters. Yet underwater, boat propellers, prop wash and wakes churn up lake beds, releasing sediment filled with nutrients and, in some cases, toxic metals. This can cloud the water, fuel harmful algae blooms and disrupt the delicate balance of aquatic ecosystems.
In particular, wake boats (which use ballast tanks to create large, surfable wakes to allow for lake-based wake surfing ) cause even larger disturbances as these high-powered boats can disturb lake bottoms up to 8 metres deep. The maximum depths of both Lake Windermere and Columbia Lake are less than 7 metres.
Lake Windermere and Columbia Lake are especially vulnerable to damage given their soft, silty bottoms that are easily stirred up. And with an average depth of 3–3.4 metres, wake boats might as well be a blade in a blender whipping sediment into a fury.
Sediment samples from Lake Windermere in a recent Lake Windermere Ambassadors-commissioned study revealed elevated levels of metals like manganese, iron, arsenic, and nickel. While hydrocarbons (from fuel and oil) weren’t a major concern, some localized contamination near marinas still needs further investigation. Copper and lead, while below regional safety guidelines, were still close to the warning thresholds of exceeding 80% of the maximum allowable concentration.
Metals released from sediments can cause decreased water quality and impacts to the food chain, which poses a threat to aquatic ecosystem health.1 Metals can be toxic to fish, interfere with photosynthesis, reproduction and growth in aquatic plants and animals, and contaminate drinking water, amongst other concerns. They can also influence conditions in the water that can lead to cyanobacteria blooms (which can be concerning, particularly for young children and animals). Not only that, research on heavy metal contamination suggests that our environmental quality standards for freshwater sediments are not stringent enough to protect against ecological risks of heavy metals. The same study2 also found invertebrates and algae in shallow lakes had higher risks from heavy metals than similar sediments in deeper water.
“Applied to shallow Lake Windermere, adverse impacts on lake health from sediment metals and contaminants should be anticipated,” reads the LWA report.3
One surprising finding from a related study4? After just two wake boat passes in moderately deep water, total phosphorus levels increase by 25%—a sharp spike that could encourage algae blooms.
And in shallow zones near Windermere Creek (that flows into Lake Windermere), sediment accumulation was unusually high — likely a combination of creek input and power boat activity.
Wildlife, habitat and invasive threats
Powerboats and infrastructure like docks and marinas fragment critical habitat, increase erosion and block sunlight essential for aquatic plants.
Native species are already showing signs of stress. Since 2007, the population of northern pike minnow—a species that thrives in disturbed environments—has increased in Lake Windermere, while redside shiners have declined.5
How many boats is too many?
According to the Lake Windermere Ambassadors study, Lake Windermere can only support nine wake boats at a time—and that’s a best-case scenario. For active wake surfing? The number drops to zero.
The study estimated Lake Windermere’s safe boating6 capacity (safety here meaning not stirring up sediment and impacting shorelines, and also safe for non-motorized watercraft and swimmers) based on depth, shoreline safety zones and boat type:
- Powerboats (using water deeper than 4 metres): about 97 boats
- Wake surf boats (using water at or deeper than 6.5 metres with 150m buffer from shore): only 4.6% of the lake is suitable, supporting about 9 boats
- Active wake surfing (using water at 8 metres or deeper): 0 boats supported (based on lake depth)
Surveys conducted over 31 summer days in 2022 and 2023 recorded more than 1,600 boats on the lake total — some days seeing as many as 210 boats. Long weekends were unsurprisingly the busiest, with boat traffic surging by nearly 3 to 4 times compared to weekdays.
Next steps
It’s not about banning boats—it’s about responsible recreation that balances enjoyment with stewardship. Some simple steps include:
- Limiting wake boats to suitable zones (or phasing them out in shallow lakes)
- Expanding no-wake zones and shoreline buffers
- Enforcing proper moorage and dock regulations
- Supporting ongoing lake monitoring and boat counts
- Practicing clean, drain, and dry protocols to prevent invasive species
The next time you’re out enjoying the lake, remember: your wake carries weight. By understanding how boating impacts water quality and habitat, we can all help protect these special lakes for generations to come.
Want to learn more or get involved? Visit Lake Windermere Ambassadors or Columbia Lake Stewardship Society and stay tuned for more updates and opportunities to support lake health.
- Zhang et al. 2023
- Zhang et al. 2023
- Lake Windermere Recreational Impact and Sediment Quality Assessment, 2024. pg 19
- Tyre, Tim and C. Luebke (2022) Wave Propagation and Water Quality Impacts on Fresh Water Lakes IN 2022 NW Wisconsin Lakes Conference Breakout 2A nwwislakesconference.org/2022-nwlc-breakout-2a/
- Pikeminnow are known to be voracious predators often out competing more sensitive native species, especially in highly disturbed aquatic environments. In 2007 the most common fish in Lake Windermere (according to the survey) were Redside shiner making up 84.1% of fish identified, while they made up only 6.5% of fish identified in our 2021 survey. What has changed to encourage these differences? During the survey Lotic Environmental pointed out Northern Pikeminnow were common in all disturbance levels, however Northern Pikeminnow were about three times as common in highly disturbed sites than in sites with moderate or low disturbance (Hildebrand, 2022). In contrast Redside Shiner and other more vulnerable native fish appeared to prefer low disturbance sites. – Lake Windermere Recreational Impact and Sediment Quality Assessment, 2024. pg 34
- Safety standards for boat density vary with lake characteristics. However, two common standards are 20 acres per boat (8 ha/boat) on lakes with high-speed watercraft and 9 acres per boat (3.6 ha/boat) on small lakes with low-powered watercraft. See Lake Windermere Recreational Carrying Capacity Study, Figure 2, page 12.
