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The Ausable River Association will hold a workshop on Thursday, November 2nd from 1 to 4:30 pm at the Crowne Plaza in Lake Placid to discuss issues related to the protection of Mirror Lake.
Mirror Lake is the jewel of the Village of Lake Placid and serves as a hub for many recreational activities in the Village and the Town of North Elba. For the past three years, AsRA, in partnership with the Adirondack Watershed Institute (AWI), has been studying the water quality of Mirror Lake.
The research has revealed several concerns for AsRA and AWI, the largest being the high concentration of salt in the lake, and the buildup of salt in the lake bottom. The primary source is road salt that makes its way from roads and walkways over impermeable surfaces and through storm drains into the lake. Current levels are warning signs for water quality, lake health, and the viability of native fish and other aquatic residents according to a press release sent by AsRA to the press.
The goal for this workshop is to share the most current knowledge about threats to Mirror Lake, to learn from others about work being done to reduce road salt regionally and in other towns and villages, and to begin a conversation with residents, business owners, and village and town officials about developing a community approach to protecting Mirror Lake.
This workshop is being held in partnership and with the support of the Adirondack Watershed Institute, Mirror Lake Watershed Association, AdkAction.org, Crowne Plaza, and the New York State Department of State under Title 11 of the Environmental Protection Fund.
Registration is free and will include coffee, beverages, and a light snack. Pre-registration by October 30th is required. The Crowne Plaza is located at 101 Olympic Drive, Lake Placid.
To register, click here.
Photo provided by Ausable River Association.
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It would be useful to know what levels of chloride (salt) we’re talking about and what levels would be considered as potentially deleterious. Elevated chlorides can result from road salt (or treated and untreated sewage) but low levels may not be any problem. Drinking water limit is 250 mg/l, far higher than anything you’d see in the Adirondacks. As far as I’m aware, impacts to the most sensitive aquatic macroinvertebrates starts around 50 mg/l. Elevated nutrients (phosphorous and nitrogen) are more typically a concern for pristine (oligotropic) lakes. Also, I’m puzzled how salt, which is water soluble, accumulates on the lake bottom. Does this mean that deeper water has higher chloride levels? Not exactly an accumulation on the bottom but higher salinity water is more dense and can stratify.
That’s why we are holding this workshop, to share what we are learning about Mirror Lake. A brief answer to your questions is below.
Surface water concentrations of chloride are typically between 36 and 49 mg/L. Bottom water concentrations range from 45 to 120 mg/L, depending on the time of year and whether the lake mixes in the spring. As a point of reference, the mean chloride concentration for Adirondack lakes not impacted by road salt is 0.24 mg/L, with the upper end of the range near 1 mg/L. In the early 1970s Mirror Lake had a concentration of 4 mg/L at the surface.
We’ve measured chloride concentrations as high as 900 mg/L in the runoff entering the lake. As a result of the increase in density and shape of the lake bottom, this water underflows the water in the lake and builds up in the lake bottom. Two out of the three years we have been monitoring the lake it didn’t completely mix in the spring, allowing higher concentrations of salt to persist at the lake bottom throughout the summer. We are still working on modeling the mixing dynamics of the lake to understand whether the lack of spring mixing is due to salt induced density differences.
Thanks for providing the details and the work of your organization. The marked difference with depth is surprising as is the high Cl levels going into the lake. We’ve been monitoring Star Lake and there have been small increases in Cl but nothing to get alarmed about.