This week, the Ausable River Association released their fifth annual report on Mirror Lake at Lake Placid
The technical brief focuses on data collected throughout the 2020 field season and documents the effects of road salt runoff entering the lake. The lake completed turnover in spring and fall of 2020 after a mild 2019-2020 winter season. This was the first time spring turnover occurred since 2016.
Elevated salt concentrations and the lack of mixing puts the lake at greater risk of algal blooms and winter fish kills and limits lake trout habitat.
Although Mirror Lake’s chloride levels were lower in 2020 than in years prior, road salt continues to be a major concern. It inhibits natural turnover and reduces lake trout habitat.
Higher chloride levels also create the optimal conditions for internal phosphorus loading with prolonged hypolimnion anoxia levels. This can lead to algal blooms in the lake, further depleting oxygen resources in the lake. Even when concentrations of phosphorus are low, the interruption of lake mixing due to road salt loading puts the lake at greater risk for harmful algal blooms.
In November of 2020, a harmful algae bloom was detected on Mirror Lake due to unseasonably warm air temperatures and calm waters. Although this algal bloom was not directly caused by high sodium and chloride concentrations, it is a reminder of the harm that can potentially be caused by high usage of road salt in the watershed.
You can read the report here.