Working in the watershed: Water quality stewardship season wraps

For yet another summer, volunteers of all ages hopped in kayaks and canoes to remove European frogbit, a non-native invasive plant species that spreads rapidly in bays and wetlands if given the opportunity.

In 2007, Lewis Creek Association initiated the Water Quality Stewardship Program and has since worked annually to manage the invasive plants and water quality of the rivers and streams that drain directly into Lake Champlain. The volunteer-driven project is the result of cooperation between many individuals and groups, including the towns of Charlotte, Shelburne and Hinesburg, Shelburne Bay Boat Club and a Charlotte property owner.

European frogbit, a common aquarium plant, spread to the United States via the St. Lawrence River after it was introduced to arboretum ponds in Ottawa in 1932. It is now considered an aquatic invasive species because it dominates native species in the competition for sunlight, nutrients and surface area.

Volunteer efforts have proven highly successful since frogbit was discovered in 50 percent of Town Farm Bay in 2007. Annual paddling and weeding trips, with a side of bird- and turtle-watching, have reduced the coverage of frogbit to just under 4 percent. In contrast, when frogbit was discovered in the wetlands of the LaPlatte Natural Area, it had a much lower percentage cover, which gave Lewis Creek Association volunteers the 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 animals to thrive.

This summer, volunteers spent 189 hours removing 600 pounds of frogbit from Town Farm Bay, nearly half the amount harvested in the summer of 2022. Volunteers spent nine hours harvesting 60 pounds of frogbit, twice the amount from last year, in the LaPlatte River wetlands. Overall, the presence of frogbit was significantly less than the previous summer.

Multiple precipitation events throughout the month of July impacted the water level of Lake Champlain, greatly increasing the amount harvested by volunteers. Frogbit became more visible to volunteers because the higher water levels submerged the native lily pads (Nymphaea odorata), which cover much of the water surface area. High water levels also allowed volunteers at the LaPlatte River wetlands to paddle into a previously inaccessible area to boaters; this area produced the majority of frogbit harvested at this location, likely because volunteers were unable to harvest from this area during previous summers. Though water levels increased visibility and access to frogbit during July 2023, the overall poundage was around 40 percent less than the amount harvested last summer.

The water quality stewardship program also includes the annual monitoring of water quality in the LaPlatte River, Patrick Brook, McCabe’s Brook, Thorp Brook, Kimball Brook and Lewis Creek, by volunteers for South Chittenden River Watch. The program is important for maintaining productive, functioning and scenic waters, and also allows residents of Charlotte, Shelburne and Hinesburg to become advocates for water quality. Volunteers in each town help share this information with neighbors and friends, helping improve water quality in the future. For more information, reach out to Kate Kelly at lewiscreekorg@gmail.com or 802-488-5203.

Kate Kelly is Lewis Creek Association program manager and Portia Butrym is an association contractor.