Vermont Community Scientists Collect Lake Water Quality Data Available to the Public

May. 18th 2023
Mark Mitchell uses a secchi disk to measure water clarity in Lake Morey

Do you have a favorite Vermont lake or pond? Are you curious about its health? You can view water quality trends and health scores for many of the more than 800 lakes and ponds in Vermont!

With plenty of help from volunteer community scientists, staff in the Vermont Lakes and Ponds Program of the Vermont Department of Environmental Conservation (DEC) monitor the water quality of these lakes and ponds, including Lake Champlain. Since 1979, hundreds of volunteers, or lay monitors, have signed up to help track the health of Vermont’s lakes and ponds as part of the Vermont Lay Monitoring Program (LMP).

Over the past 40 years, this dedicated group of community scientists have monitored more than 100 inland lakes and 40 Lake Champlain stations, many of them for multiple years.

“Monitoring lakes and ponds has helped to establish baseline conditions so that long-term changes in water quality and nutrient trends can be tracked,” said Mark Mitchell, Lake Monitoring and Community Outreach Coordinator with Lake Champlain Sea Grant and Lay Monitoring Program Lead with the Vermont DEC.“The lay monitoring program also helps to educate lakeshore homeowners and lake users about aquatic ecology and stewardship.

Tools You Can Use

Through the lake monitoring program and its many community volunteers, the state has collected more than four decades of data. Long-term trends indicate most lakes have relatively stable or improving nutrient conditions, though many lakes and stations show degrading conditions.

Annual data and water sample analyses and reports for each lake and pond can be found in two online locations. On the Vermont Integrated Watershed Information System website, you can find lake water quality and chemistry testing information from throughout Vermont. The LMP website reports section posts monitoring reports and lab results, water quality and chemistry trends over time, and Lake Score Cards, which give ratings that show how disturbed the lake watershed and shoreland are and how stressed the lake is based on water quality.

Water Sampling to Monitor Lake Health

Each summer, volunteers are trained to collect water samples and take water quality measurements from Memorial Day to Labor Day. Using their own boats, they sample about every week to ten days.

Mitchell and other LMP staff pick up and deliver the water samples to the Vermont Agriculture and Environmental Laboratory, where lab staff test for total phosphorus and chlorophyll-a, a green pigment which gives an indication of algae or cyanobacteria levels. Generally, lakes with higher phosphorus concentrations will have more algae and cyanobacteria growth.

Human activity along a lakeshore and throughout a lake watershed can accelerate the amount of phosphorus entering a lake. Sources of phosphorus include shoreline erosion, fertilizer run-off from agricultural land and residential lawns, failing septic systems, and erosion from construction and logging.

Lay monitors also measure water clarity with a Secchi disk, an eight-inch diameter disk with black and white quadrants. They lower the disk into the lake by a rope, marked in meters, until the disk disappears from sight, which is the Secchi depth. Sometimes volunteers use a special view tube to better see the Secchi disk in the water. The greater the Secchi depth, the greater the water clarity. Water clarity tends to decrease as chlorophyll-a concentration increases.

In 2022, lay monitors visited 83 inland lakes and ponds and eight stations on Lake Champlain. They collected water for phosphorus and chlorophyll-a analyses from 66 of the lakes, ponds, and stations.

“Over the course of years, I have had the good fortune to spend a lot of time at Lake Morey,” said Don Weaver, a lay monitor for 31 years in Fairlee, Vermont. “I have participated in numerous activities to preserve and protect the lake. Perhaps the most extensive is the Lay Monitoring Program. I like knowing that I am helping to keep the lake healthy for future generations.”

Mitchell trains lay monitors, provides them with collection supplies and Secchi disks, and visits each volunteer yearly to answer questions and provide updates on sampling protocol. He assesses lab results and water clarity data for compliance with Vermont Water Quality Standards and completes annual reports and a quality assurance project plan for the U.S. Environmental Protection Agency (EPA).

Findings Inform Management

The LMP has documented an increase in phosphorus levels and a subsequent rise in algae and cyanobacteria in many of Vermont’s lakes and ponds. The DEC prioritizes management of lakes that show increasing total phosphorus trends. For these lakes, staff recommend volunteer monitoring of lake tributaries and Lake Watershed Action Plans to identify pollution sources and recommend restoration and protection projects.

In worst-case scenarios, unnaturally high levels of phosphorus can result in excessive growth of algae, cyanobacteria, and aquatic plants which decreases water clarity. As the excessive growth dies back each year, it falls to the lake bottom, where it decomposes, depletes oxygen, and adds phosphorus to the bottom sediments. Once there is no oxygen left at the bottom of a lake or pond, a chemical process in the sediments releases phosphorus which can rise to the surface and cause an unhealthy increase in algae and cyanobacteria. This is called internal phosphorus loading. When the natural habitat of a lake is altered in this way, fish and wildlife populations using the lake may also change.

The DEC has listed Lake Carmi in Franklin, Ticklenaked Pond in Ryegate, and Lake Morey in Fairlee as impaired, partially due to internal phosphorus loading. Staff have or will conduct diagnostic sediment studies for these lakes, and Ticklenaked Pond received a successful alum treatment in 2014 to inactivate phosphorus in the sediment.

Even some of Vermont’s clearer lakes currently have high levels of phosphorus and chlorophyll-a, such as Great Hosmer Pond in Craftsbury and Albany, Lake Fairlee in Fairlee, and Valley Lake (or Dog Pond) in Woodbury.

“For these lakes, Secchi depth measurements meet Vermont clarity standards, but lake levels of phosphorus and chlorophyll are below standards,” said Mitchell.

He points out that volunteers have been taking Secchi disk readings in the deepest water of the lakes, where clarity is usually better. For the 2023 season, lay monitors will instead collect six surface and optional deep grab samples up to 20-meters deep or at least one meter off the lake bottom to analyze phosphorus and chlorophyll-a by depth. He will also request that the lab conduct caffeine testing of water samples to check for human wastewater sources of pollution from septic systems.

“Thanks to the sampling efforts and activism of lay monitors, the DEC can more effectively assess, restore, and protect water quality in Vermont’s lakes,” said Mitchell. “If caffeine results show detectable concentrations, especially if some are higher, then we can present this data to municipalities, town health officers, lake associations, and other stakeholders to take action on inspecting and improving septic systems in partnership with the DEC.”

Learn More

Find lake water quality and chemical testing information on the Vermont Integrated Watershed Information System website, and find lake monitoring reports, lab results, water quality trends, and lake score cards on the Lay Monitoring Program website.

For more information on volunteering with the Vermont Lay Monitoring Program, email or call 802-490-6126.

Learn more about the Vermont Lay Monitoring Program and view a video recording of Mark Mitchell’s webinar about the program, part of the Lake Champlain S