Working in the watershed: Wrapping up the water quality stewardship field season

A volunteer removes a European frogbit plant from the water by hand. Photo contributed.

Among the great egrets and northern map turtles in Charlotte’s Town Farm Bay and Shelburne’s LaPlatte River wetlands, volunteers removed invasive European frogbit plants for the 13th consecutive year during July and August. Lewis Creek Association’s (LCA) “Water Quality Stewardship Program” is an invasive-plant and water-quality project coordinated annually since 2007. It is supported by LCA, the towns of Charlotte and Shelburne, Point Bay Marina, Shelburne Bay Boat Club and a property owner in Charlotte.

Native to Europe and Northern Asia, European frogbit was first introduced to arboretum ponds in Ottawa in 1932 before spreading to the United States via the St. Lawrence River. It is considered an aquatic invasive species because it grows on the water surface and outcompetes native plants for sunlight and nutrients. In 2007, friends of LCA discovered frogbit covering 50 percent of Charlotte’s Town Farm Bay wetland. Through volunteers’ annual seasonal field work, the frogbit cover has been substantially reduced and is now maintained at about 5 percent cover.

In contrast, when frogbit was discovered in the LaPlatte River and McCabe’s Brook wetlands (LaPlatte Natural Area), it had a low percent cover, providing an opportunity for “early detection, rapid response.” Though the invasive plant will never be eradicated in either location, maintaining this low population allows native plants and critters to thrive.

This year, volunteers removed 677 pounds of frogbit from the 50-acre Town Farm Bay wetland complex and 612 pounds of frogbit from the 77-acre LaPlatte River wetland complex. Final amounts of European frogbit were estimated to be less than 5 percent cover at each location.

Because current frogbit levels are consistently low, LCA and volunteers are now taking on the management of other invasive species. Under advice from advisors at the Vermont Department of Environmental Conservation and the Lake Champlain Basin Program, LCA has begun a study of flowering rush (a non-native invasive species that can also crowd out native plants) and the best methods for removal/control of it in Town Farm Bay. Some flowering rush plants and seed heads were removed from both Town Farm Bay and the lower LaPlatte River. Volunteers also discovered and removed three water chestnut plants from Town Farm Bay. Next year, these studies of flowering rush will proceed, to be followed by development of management/control practices for the species.

LCA’s Water Quality Stewardship Program also includes the annual monitoring of water quality in the LaPlatte River, Patrick Brook, McCabe’s Brook, Thorp Brook and Kimball Brook by volunteers for South Chittenden River Watch. The sampling season is still in progress and will last into November.

Volunteers collect water samples that are then analyzed by the Vermont Agricultural and Environmental Laboratory and interpreted by LCA technical consultants. This year, LCA continues to sample nutrients and solids during high flow events like heavy rain or snow melt in order to understand sources of nutrient loading to Lake Champlain while informing water quality improvement project plans. We also sample at low flows to be able to compare levels of nutrients to the state standards. To see 2018 results, visit the LCA website at Results for 2019 will be available on our website in the spring of 2020.

Not only is this water quality stewardship program important for maintaining productive, functioning and scenic waters, it also allows residents of Charlotte and Shelburne to become involved as advocates for water quality. Volunteers in each town will help share this information with neighbors and friends to help improve water quality in the future. This program being funded through your town budget is crucial, since it allows the whole community to take ownership of local water quality and natural resources that are so important to protect. The end result is a healthier ecosystem that all citizens can enjoy.

If you are interested in assisting with water quality monitoring or invasive plant removal in 2020, please reach out to Kate Kelly via email or by phone at (802) 488-5203.

Kate Kelly is the LCA program manager.