Thompson Lake is one of the 5% cleanest lake in our part of the State.

       Help TLEA Keep It That Way !

Thompson Lake is noted for its water quality and TLEA is committed to protecting this resource. To do this, we monitor the lake throughout the open water season to detect any downward trends that may result from erosion and warming water temperatures. This is done through serial Secchi Disc readings performed by TLEA volunteers and monthly water analysis by our licensed limnologist from May through September.

The Secchi disc readings in 2023 were done by John Powers and Paul Cain. These were performed off Hayes Point (Station #1) and off Megquier Island (Station#2) in some the deepest spots of the lake. Both volunteers have been trained and certified by the Lake Stewards of Maine, and their measurements are entered into their data bank. Secchi Disc readings involve anchoring at the specific stations and watching the disc descend into the lake through a monitoring tube. The depth in which the disc becomes invisible is a reliable indicator of the water clarity, which in turn, is a good indicator of quality.

Our contracted limnologist is Scott Williams, the former President of the Maine Congress of Lake Associations (now Maine Lakes) and currently Senior Advisor for Lake Stewards of Maine. Scott visits the lake monthly from May through October to take measurements of the water clarity and temperature, dissolved oxygen, total phosphorous, chlorophyll-a (an indicator of planktonic algal density), total alkalinity, and inspection for the algae Metaphyton and Gloeotrichia. Scott then reviews data from various Maine lakes, precipitation patterns, ambient temperatures, length of ice coverage, as well as historical data to produce an Annual Water Quality Report. This report alerts us to any disturbing trends and compares Thompson Lake to other lakes in Maine. If needed, recommendations are made to improve our efforts to maintain our water quality. Links to these annual reports are on this page.

Maintaining high water quality in a lake is an ongoing battle, made worse by the effects of climate change, warming waters and shoreline development. In recent years surrounding lakes have seen loss of clarity and algal blooms. Through proper monitoring and erosion control, TLEA is fighting to preserve the exceptional water quality of Thompson Lake.