Opportunities / Progress / Science

Celebrating Vermont lake water clarity and the citizen scientists that measure it

As we celebrate Lakes Appreciation Month, we want to again highlight important findings about Vermont lakes, which were summarized in a blog post earlier in the spring, as well as the volunteers that helped to produce these results.

Vermont ranks among the leading states in the nation for clear lakes according to research published in February 2015 in the journal Lake and Reservoir Management. Dr. Dana Bigham Stephens at the University of Florida and her colleagues utilized Secchi disk transparency measurements from over 14,000 lakes and reservoirs across the United States to compare regional differences in lake water clarity.

Used by professional and citizen scientists alike, the Secchi disk provides a simple but scientifically valid measurement of water clarity.  About the size of a dinner plate and painted with black and white quadrants, a Secchi disk is lowered into a lake with a calibrated line.  The water clarity measurement is the lowest depth at which the disk can still be seen.

Lay Monitors Lee and Mary Stewart sample Maidstone Lake (Lin Mixer, not pictured, also assists with monitoring Maidstone)

Lay Monitors Lee and Mary Stewart sample Maidstone Lake (Lin Mixer, not pictured, also assists with monitoring Maidstone)

Vermont’s lakes, with a median water clarity of 4.0 meters (13 feet), ranked fourth among all 50 states, behind only Alaska (5.9 m), Montana (4.8 m), and Maine (4.6 m), and just ahead of New Hampshire (3.8 m).  Volunteers with the Vermont Lay Monitoring Program have been recording Secchi disk transparency for more than 90 Vermont lakes since 1979 and their data were used in this research.

In addition to measuring water clarity, nearly this entire network of dedicated citizen scientists also collects water samples weekly through the summer. These water samples are tested for total phosphorus and chlorophyll-a. Phosphorus is typically the limiting nutrient in a lake system and when in excess, feeds aquatic plants and algae. Chlorophyll-a is the green pigment in plants and algae used to describe the amount of algae in the lake. Generally, lakes with high phosphorus concentrations will have increased algal growth and lower water clarity.

Through the Lay Monitoring Program and the dedication of hundreds of volunteers, we now have a much better understanding of long-term water clarity and nutrient enrichment trends in Vermont lakes, and the ability to monitor future changes in lake health.  So let’s not only celebrate Vermont lakes, but also recognize the many citizen scientists past, present, and future that invest their time and energy so we may better know and protect our lakes.

Lay Monitoring Program long-term summer means for Secchi disk transparency (lakes depicted were sampled in 2014)

Lay Monitoring Program long-term summer means for Secchi disk transparency (lakes depicted were sampled in 2014)