The Village of Lake Placid owes much of its picturesque charm to its proximity not to Lake Placid but to Mirror Lake. This small lake's headwaters are located on the slopes of Mt. Whitney and Cobble Hill. Water drains into Echo Lake and then on to Mirror Lake which empties into the Chubb River, a major tributary of the West Branch of the Ausable. Of its 1.2 total square miles, 26% of the Mirror Lake watershed is developed, 19% is surface water, and 55% is forested. A significant portion of downtown Lake Placid sits within the Mirror Lake watershed and Main Street runs along the lake's western shore. This proximity poses significant challenges to maintaining the lake's water quality.
The primary challenges facing Mirror Lake are high levels of chloride and sodium and low oxygen in the deep waters. Mirror Lake has higher levels of chloride and sodium than 97% of the other lakes surveyed as part of the Adirondack Lake Assessment Program. These pollutants enter the lake via the application of road salt to both local and state roads within the watershed. Increasing concentrations of these ions threaten the ability of the lake to support healthy fish populations and other aquatic life. The reduced oxygen in the lake bottom may be a natural phenomenon that is being excaserbated by development, road salt runoff, and climate change.
AsRA and the Adirondack Watershed Institute (AWI) have launched a year-round monitoring program on Mirror Lake. This work has been supported by the Mirror Lake Watershed Association, Town of North Elba, Village of Lake Placid, IRONMAN Foundation, and New York State Department of State. This program will help us better understand the threats facing Mirror Lake and gauge the success of programs to mitigate those threats. We collect vertical profiles of temperature, dissolved oxygen, conductivity, and pH year-round, including through the ice during the winter months. In addition, we collect surface and deep-water samples to be processed with our partner, the Adirondack Watershed Institute. In the spring of 2016 conducted stormwater outfall monitoring to help us better understand where pollutants such as road salt are originating from.
2016 Water Quality Report
Mirror Lake has been enrolled in a variety of water quality monitoring programs over the past 45 years. These range from citizen volunteer water quality monitoring programs to studies conducted by a variety of contractors and researchers. The purpose of this report is to summarize all the available water quality data on Mirror Lake to develop a comprehensive understanding of the current state of the lake. This report will serve as the basis for future decisions on how best to continue to monitor the health of Mirror Lake, and how to develop effective programs to reduce water quality impairments. Report highlights include:
- There are challenges with comparing historical data to current monitoring efforts due to inconsistency in sampling methodology, frequency, and location over time. Developing a rigorous, methodologically sound, monitoring program is important to understanding future and ongoing changes in the health of Mirror Lake.
- Measures of the lake's trophic status (total phosphorus, nitrate, chlorophyll-a, transparency, and trophic state index) do not show significant long-term trends. Earlier reports of increasing total phosphorus may be the result of inconsistency in sampling location.
- The lake experiences seasonal anoxia (no oxygen) in the bottom waters during the summer stratified period. There is not enough long-term data to assess whether this a natural condition of the lake or the result of urban development in the watershed. This condition, coupled with potentially longer periods of stratification, may pose a long-term threat to the lake trout population.
- Calcium concentrations are higher today than measurements made in 1971. Current concentrations are within the reported ranged need to support a viable zebra mussel population.
- There are significant long-term trends of increasing sodium and chloride in the lake. Concentrations are 9- and 11-times higher than the early 1970s, and 52- and 239-times higher than Adirondack lakes not impacted by road salt, respectively. Chloride builds up in the bottom waters of the lake during winter and spring.
- Stormwater directly entering the lake through outfalls contributes high concentrations of total suspended solids, chloride, and total phosphorus to the lake. High concentrations of all three parameters are found at locations that drain state maintained roads and areas that drain village and town maintained roads and sidewalks.
The full report can be viewed here.
Older recent reports from the Adirondack Lake Assessment Program and the Citizens Statewide Lake Assessment Program can be downloaded from the sidebar of this page. Monitoring data for Mirror Lake extends back to 1998 and can be found here.