August 15, 2025
Each year, the Lake George Association (LGA) and our partners at the Jefferson Project monitor hundreds of data points to track the health of Lake George. This scientific work is the foundation of our mission — it tells us what’s changing, what’s stable and where action is urgently needed.
Our recently released 2024 Annual Report reflects both encouraging progress and growing challenges. The findings underscore why the LGA focuses its work on the five main threats to Lake George: road salt, nutrient pollution, harmful algal blooms (HABs), climate change and invasive species.
What the Trends Show
Increasing Trends:
- Winters without full ice cover – Lake George is seeing more winters where ice fails to cover the lake from end to end, a result of climate change.
- Surface-level water temperatures – The top three feet of the lake are warming, creating conditions that can encourage HABs and alter aquatic habitats.
- Temperature difference through the water column – Larger temperature gaps between surface and deep waters affect nutrient cycling and oxygen availability.
- Phosphorus levels – This key nutrient, often carried into the lake by stormwater runoff, has been rising over the past 40 years.
- Chlorophyll-a concentrations – Elevated levels of this algae pigment indicate more algal growth, which can threaten water quality.
Decreasing Trends:
- Chloride levels – Thanks to regional road salt reduction efforts, chloride levels in Lake George are showing signs of decline. This is a clear sign that science-driven solutions are working and puts an emphasis on continued work.
- Nitrogen levels – This nutrient, which can fuel plant and algae growth, is also trending downward.
Stable Trends:
- Water clarity – Lake George remains one of the clearest large lakes in the world, underscoring the importance of continued protection.
- Deep-water temperatures (85–100 ft) – These temperatures have remained relatively steady, even as surface waters warm. This pattern has also been observed in many other lakes, with warming surface waters and stable deep-water temperatures. This phenomenon means that the temperature difference through the water column is increasing over time, which can be a barrier to the mixing of oxygen from the air to the lake bottom. When oxygen gets too low, it can harm aquatic organisms like fish and zooplankton - the base of the food chain.
How These Trends Connect to the LGA's 5 Main Threats
- Road Salt – The decreasing signs in chloride levels shows the success of smart salt reduction practices, but more work is needed to expand adoption and ensure long-term impact.
- Nutrient Pollution – Rising phosphorus and stable nitrogen levels highlight the importance of reducing nutrient inputs from stormwater runoff, septic systems and shoreline development.
- Harmful Algal Blooms (HABs) – Warmer surface waters and rising nutrient levels create conditions where HABs are more likely to occur.
- Climate Change – Fewer winters with full ice cover and increasing surface temperatures are direct indicators of climate shifts impacting the lake. Warmer, wetter summers also fuel more intense storms, leading to increased nutrient pollution in the watershed.
- Our new Stormwater Grants for property owners help create stormwater mitigation projects on properties around the lake, to combat the negative effects of increased nutrient pollution.
- Invasive Species – Warmer temperatures could lead to an increase of aquatic invasive species. Warmer waters can expand ranges of existing invasive species, allowing them to thrive in areas previously too cold for them. Additionally, warming can provide a competitive advantage to warm-water adapted invasive species.
Where We Go From Here
These water quality trends make it clear: our science-based solutions are working, but the challenges are evolving. The LGA's work is designed to address these threats head-on.
You can explore these trends, our accomplishments and the path forward in our recently-published 2024 Annual Report.
