Hand Harvesting Weeds: A Community Effort to Save our Lake

On a breezy and hot day in mid-July, 2014, on a Sunday afternoon when most people who live on a lake would usually be boating, swimming, or barbecuing, a dozen Chepachet homeowners and their friends took turns diving into a murky lake bottom to remove invasive plants that crowd out native species.

“It was more fun than I expected,” Sam Hawkes, who pulled weeds for several hours, acknowledged.

This group of concerned citizens on Sand Dam Reservoir in northwest Rhode Island removed variable-leaf water milfoil plants by hand, including roots, from targeted sites by diving to the lake bottom, with or without masks and fins. James, a SCUBA diver, later took over from the initial group of swimmers and divers. Neighbors and friends who lent a hand included year-round and summer residents, retired and middle-aged people and youth. No matter their age or background, everyone pitched in by diving for weeds, collecting the harvest in rowboats, or supervising swimmers from motorboats.

Ray Theriault, president of Sand Dam Reservoir Association (SDRA), led the project, which included organizing pontoon and other boats, getting volunteers, scheduling, and coordinating via emails. Hand harvesting, Ray said, “is a great community effort to help the Association save money and eradicate invasive weeds.”

What is variable milfoil?

Variable-leaf watermilfoil (Myriophyllum heterophyllum) is a nuisance aquatic plant in the northeastern United States. It grows in thick mats, often out-competing native vegetation, clogging boat motors, and deterring people from swimming and other water-related activities. Milfoil spreads rapidly. In Rhode Island, milfoil has no natural predators to keep its population in check. Under optimum temperature, light and nutrient conditions, milfoil may grow up to an inch per day.

How did variable milfoil spread to RI lakes?

According to RI DEM, variable milfoil was most likely introduced to RI lakes from aquarium releases or from “stowaway” fragments attached to a boat or trailer. When milfoil is wound around a wet carpeted bunk on a boat trailer, it can live out of water for many hours if it remains moist. Milfoil is usually first found near boat launch sites. Once introduced, milfoil can spread through fragmentation, whereby plant fragments break off from the parent plant through wind or boat action, grow roots, and settle in a new location.

Why hand harvesting?

In July, variable milfoil plants may exhibit a three- to six-inch emergent spike above the waterline, so July makes an optimal time for hand harvesting to slow its spread. Although eradication is seldom achieved, various studies indicate that variable-leaf milfoil infestations can be managed effectively by incorporating the use of hand removal and mats in lake management plans.

Removal by hand is an effective management technique for waterbodies with small, high density stands of variable-leaf milfoil or when milfoil plants are interspersed among the natives. Removal by hand is a fairly inexpensive technique to implement, but it is also time and labor intensive. “The winds created a problem for us harvesting,” Ernie Heon, who ran a pontoon boat during the hand harvesting, admitted. “We detached an aluminum boat and brought it into shallow water. My original intent was to bring the pontoon boat into the site, but it didn’t work like that.”

The hand harvesting method is also useful during follow up surveys of management areas when individual or small clusters of variable-leaf milfoil are detected, as was the case on Sand Dam Reservoir. Immediate removal decreases the opportunities for further spread of the plant.

Other methods to slow the spread of variable milfoil

 Sand Dam Reservoir Association has a volunteer regular boat greeter program to educate people about invasive species. When bass tournaments are scheduled, a small group of SDRA members greets the fishermen and women as they ready their boats for launch. Mary O’Keeffe, the project director, describes the importance of educating boaters about cleaning their boats to limit the spread of invasive species. “Rhode Island is the only New England state that doesn’t hire people to work at boat launches to educate boaters,” she stated. “That really makes it important for community members to come together to promote proper boater hygiene.”

RI DEM also encourages the use of clean boat hygiene practices. They concur that boats, trailers, and motors should be inspected for plant fragments before launching in the water and after boats have been hauled out of the water.

Community building while hand-harvesting

During the SDRA weed pulling, lake property owner, Sharon Heon maneuvered a rowboat and collected weeds as swimmers transferred them to her. “It was an enjoyable experience,” she offered, “being with Association members on a worthwhile effort.”

Community members who participated in the effort included Tommy Hopkins, Sharon and Ernie Heon, Sam Hawkes, Bob Bedard and his granddaughter Sammy, John Guertin, Cleo Monti, Eric and Carol and Austin Lariviere, Art and George and Bob Searles, Carolyn Fortuna, Mary O’Keefe, Aaron and Judy and Rico Colaluca, and Elaine and Ray Theriault, and James, the diver.

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