Mirror Lake is seen here in October 2015. (News Photo – Andy Flynn)
LAKE PLACID — Preliminary data from the Adirondack Watershed Institute reflects a further decline in salt levels in Mirror Lake this year, which AWI principal investigator Brendan Wiltse says is likely the result of local efforts to salt reduction.
Wiltse, along with the staff of the AuSable River Association, was thrilled to bring some good news with this year’s preliminary data from Mirror Lake at Heaven Hill Farm on Thursday August 25th. The presentation was a preview of the AWI’s final report, detailing last year’s salt levels in the lake. Preliminary data shows improvements to Lake Placid’s stormwater system had measured effects on salt reduction in Mirror Lake last year, and Wiltse said salt use around Mirror Lake decreased by about 9-12% as a result of the salt reduction efforts put in place. place in the town of North Elba and the village of Lake Placid. Wiltse said salt levels in the lake started to drop in late 2019, but he added there was still work to be done.
Mirror Lake is the most “developed” lake in the Adirondacks Park, according to Wiltse, and it is one of the saltiest – only Lake Colby and the Cascade lakes exceed Mirror Lake’s chloride levels. Wiltse said excessive salt use nationwide often stems from the modern expectation that roads should be as clear on a snowy day as any other. He added that there is a common history in the region that the 1980 Winter Olympics in Lake Placid was a big factor in increasing salt usage in the Adirondacks. But to most effectively protect Mirror Lake’s aquatic life and water quality, Wiltse estimated salt use should be reduced by about 75 percent from current practices.
Salt concentrations are measured in milligrams per litre, and Wiltse said Mirror Lake levels were 4 mg per liter in 1974. Today they are just over 40 mg per litre. Wiltse said AWI’s overall goal is to see Mirror Lake salt levels come down to 10 mg, which “really protect the lake.” This would require reducing salt use to a third of what it is now. For now, AWI aims to reduce Mirror Lake levels to less than 40mg. That would require a 3-5% reduction from current salt-use practices, Wiltse said.
Park-wide, Wiltse points to the salting practices of the state Department of Transportation as the main problem. He said the state sets the most salt per area, and while he hoped the state would be a “voluntary partner” providing its data on salt use for the AWI study – such as the Village of Lake Placid, which attached cameras to its plows so AWI could track the amount of salt applied to the roads – it said a Lake George group had to submit Freedom of Information Act requests for state plow data and it took between 12 and 16 months for the state to return that information. Wiltse believed that the state road salt task force, which presented an outline of its final report and recommendations for salt reduction earlier this month, planned to recommend a 50% reduction in salt. use of salt throughout the park.
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Why salt is important
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Mirror Lake completely turned around this spring for the first time since 2020, and for only the second time in the past five years. Mirror Lake failed to transform in 2017, 2018, 2019 and 2021 due to high salt levels in the lake – a direct result of road salt use, according to Leanna Thalmann, associate of the water quality from the Ausable River Association. Salt water is dense and settles to the bottom of the lake, which can prevent mixing. This year, salt levels were lower and more storms after the ice disappeared from Mirror Lake on April 14 helped the lake turn over.
Renewal is important for large lakes because the process replenishes oxygen and distributes nutrients throughout the lake. Renewal is a process that most lakes go through each fall and spring, according to the Ausable River Association. It is the natural process of the dense, colder water of a lake sinking to the bottom of the lake and mixing with the deeper water. The water is at its peak at around 39 degrees Fahrenheit, so when the ice melts and the upper cold water layer of the lake begins to warm up a bit, it falls to the bottom of the lake and mixes with the water more deep.
In recent years, Mirror Lake’s turnover has been disrupted by high salt concentrations in the lake. When a lake does not turn over, there is less oxygen on its bottom, which can lead to several adverse effects on the lake biome, such as algal blooms. If a harmful algal bloom spread across Mirror Lake, Wiltse said, people would not be able to swim or paddle in the lake. Rolling is especially important for Lake Trout and Mirror Lake Trout, which like to hang out in the cooler water at the bottom of the lake.
