Chloride concentrations in Mirror Lake – one of the region’s most developed lakes – declined slightly last year, but the lake again failed to complete a turnover in spring 2021, according to an annual report from the Ausable River Association.

The report, released earlier this month, attributed the chloride decline to a mild winter season, improvements to the Village of Lake Placid’s stormwater runoff system and a new program to reduce private and public road salt use around the lake.

Mirror Lake is one of the lakes most impacted by salt pollution in the Adirondack Park and has been the focus of the Ausable River Association and local officials seeking to limit salt contamination. Still, researchers measured chloride concentration of 52 mg/L, much higher than chloride levels found in lakes unimpacted by salt runoff.

“Although the recorded chloride concentrations were lower in 2021, they still are not in the range of our water quality targets,” according to the report. “Our short-term goals include achieving concentrations less than 40 mg/L of chloride, and our long-term goals aim to record chloride concentrations less than 10 mg/L, or close to the records from the 1970s.”

I couldn’t make it but researchers presented the latest from Mirror Lake monitoring at an event last week on the “state of the lake.” Road salt continues to be a major concern and inhibits the lake’s natural turnover.

Mirror Lake has registered low oxygen levels in deeper waters, reducing important habitat for lake trout and other aquatic organisms. The lake’s failure to turnover minimizes the important mixing of lake layers, which distributes oxygen more evenly throughout the waterbody.

ALSO:

• Adirondack conservation legend Tim Barnett died this week.
• Dry weather could be leading to more bear euthanizations than previous years, via Albany Times Union.
• Walk along the LaChute River in Ticonderoga for a valuable history lesson in how Adirondack rivers have long been harnessed for their power.

Editor’s note: This first appeared in Zach’s weekly “Water Line” newsletter. Click here to sign up.