Science

Vermont Lakes are Some of the Best Lakes in the Nation

Great Averill Pond in Averill, Vermont is one of Vermont’s high quality, clear water (oligotrophic) lakes.

This past year, there were multiple stories in the media covering massive algal blooms in Lake Carmi, tons of phosphorus pouring into state surface waters, and the seemingly never-ending efforts to clean up Lake Champlain. These stories would leave many Vermonters to believe that Vermont’s lakes are in deep trouble. While these issues are very important, and restoration will be addressed through long-term management activities across multiple sectors, these headlines are not representative of the majority of the lakes and ponds of Vermont.

Despite some very serious water quality issues, Vermont has some of the best water quality in the country. In addition to Lake Champlain, Vermont has over 800 inland lakes and ponds. For the last 40 years, the Lakes and Ponds Management and Protection Program has collected phosphorus data on Vermont’s inland lakes at spring turnover.

For almost as long, volunteer citizen lay monitors have collected phosphorus, chlorophyll-a and water clarity (Secchi depth) data throughout the summer. Five years of data are needed on a lake before a trend can be calculated. Trends describe how the water quality changes over time. Of the 219 inland lakes with trend data, 79% have stable or ‘good’ nutrient trends, 16% have ‘fair’ trends and only 6% have ’poor’ trends that are statistically significant.

For the first time, thanks to Vermont’s enhanced participation in EPA’s National Lake Assessment, we were able to directly compare the condition of Vermont’s lakes to those in the nation. It turns out that Vermont is home to some of the clearest low-nutrient lakes, called ‘oligotrophic’ lakes by limnologists.  In fact, Vermont has a higher proportion of oligotrophic lakes than the nation, and eight of the nine ecoregions in the lower 48 states (see figure below). Additional national-level research rated Vermont as one of the top 5 states with the greatest water clarity.

Vermont has more clear lakes than the national average and other regions.

However, recent analyses of the last 40 years of spring phosphorus data have found a disturbing trend in Vermont’s oligotrophic lakes. One hundred percent of Vermont’s oligotrophic lakes have increasing phosphorus trends, with some lakes moving from oligotrophic to mesotrophic, which is defined by poorer water clarity and increased algal and aquatic plant growth. If no action is taken, Vermont risks losing its oligotrophic lakes and joining the rest of the country in mediocrity. The good news is that Vermont’s oligotrophic lakes can still be saved. Vermont has successfully turned increasing nutrient trends around on some of its most nutrient-rich lakes through watershed protection and restoration efforts.

One of the biggest threats to water quality is unchecked development on the landscape and the lack of riparian buffers. Protection of these special lakes can best be achieved through maintaining vegetated buffers along streams and lakeshores. Additionally, lake-friendly housing development, well maintained roads, and the installation of best management practices all contribute to protecting and maintaining water quality. By committing to healthy watersheds, Vermont can continue to boast that it has some of the clearest lakes in the nation!