This fall, the Lake Waramaug Task Force (the Task Force) installed four submersible mini-Dot® temperature / dissolved oxygen data loggers into Lake Waramaug (the Lake). Strung together in a line, each logger was placed at a different depth and collects hourly water temperature and dissolved oxygen concentrations year-round. This data will help the Task Force to forecast favorable conditions for cyanobacteria blooms and understand how the Lake gains and loses heat. In this way, we can prepare for and combat the negative water quality effects of climate change. 

    Climate change can greatly alter and affect our natural resources. Moving forward, the most effective lake management requires planning for climate resiliency. Lakes vary on their vulnerability to climate change depending on a variety of characteristics, such as land use within the watershed, orientation and lake-shape (which controls how a lake is impacted by wind patterns), depth and overall lake stratification patterns. It is hard to predict how a lake will respond to fluctuations in climate. From drought to intense precipitation events, to warm/short winters to long/harsh winters, each year and each season is becoming more and more unpredictable. We need more long term high frequency data to truly understand how a lake responds to these different stimuli. By installing the mini-Dot dataloggers, the Task Force can collect more frequent and more accurate data that will enable us to better understand the Lake’s response to climate shifts. The data will help the Task Force build a long-term database that is more consistent, creating a foundation to help direct future water quality monitoring and improvement projects.

     These data loggers increase the capability of the Task Force to obtain Winter data. In recent years, the ice has not been stable enough to bore through to get vertical profiles, limiting our ability to collect winter data-sets. The timing of winter ice-on and ice-off plays a very important role in setting the Lake up for the following summer season. The sooner ice leaves a lake, the sooner the lake can stratify, increasing the time-frame for cyanobacteria to thrive. In recent winters, conditions have swung between heavy snow to 50 F° weather within a week, which can influence how a lake behaves the following summer. Without actual data, it is hard to predict and manage how the Lake will react, not to mention keep the public informed as well. 

   The new set of data loggers will also better inform the Task Force on mix-down events during major storms, where cold nutrient-laden stormwater runoff enters the Lake causing the warmer surface water to mix and disrupting lake stratification. While our weekly Lake monitoring enables the Task Force to adapt to Lake changes throughout the season, there are often large holes in the data. When large precipitation events occur, we can miss brief but significant shifts in the Lake’s response to storms. For example last summer, while the Task Force obtained data before and after the major wind storm in August (Isaias), our real-time understanding of how the Lake reacted was limited. Our new in-lake dataloggers will track those kinds of events much more effectively. 

     The Task Force also placed a data logger just south of the Sucker Brook delta to understand how the brook interacts with the Lake in this sensitive area. Sucker Brook is the largest single source of water that feeds Lake Waramaug, representing about 65% of total Lake inflow. A two acre, 10 foot thick sediment delta has formed where Sucker Brook enters the Lake. When cold, well-oxygenated nutrient-laden water from Sucker Brook enters the Lake, it is quickly warmed as it spreads across the shallows of the delta. The buoyant nutrient-laden warm water then remains at the surface, readily available to cyanobacteria that cause toxic blooms. The datalogger’s information will help the Task Force better understand how Sucker Brook impacts Lake water quality and be a valuable asset when designing future projects to manage the delta.  

      The Task Force would like to extend a huge thanks to the Lake Waramaug InterLocal Commission, whose funding made the purchase of the data loggers possible. To learn more about this project, please watch the video below. 

March 17th, 2021

Task Force Executive Director, Sean Hayden, deploying string of dataloggers

The full string of data-loggers above water on Task Force Research Boat. Driver- Peary Stafford, Task Force Chairman, Deploying string - Sean Hayden, Task Force ED

The cinder block anchorage of the Mini-Dot string of dataloggers underwater