BELGRADE — While kayaking in August on the Serpentine Stream, which connects North and East ponds in the Belgrade Lakes Region, Bonny Jones noticed an aquatic plant she had not seen before.

She decided to collect a sample of the plant, which matted at the surface but did not have floating leaves and notified the 7 Lakes Alliance, a Belgrade-based conservation group.

The sample was sent away and later identified as curly leaf pondweed, a plant native to Africa, Australia and Eurasia.

The concern among the 7 Lakes Alliance and others is this latest invasive plant threat could spread quickly to nearby North Pond and other parts of the Belgrade Lakes watershed. The health of the lakes is imperative to drawing tourists, boaters and others to the area.

An effort by the alliance, the Maine Department of Environmental Protection, Colby College in Waterville and the North Pond Association to prevent the spread of curly leaf pondweed coincides with a push to add North Pond to the state list of “impaired” lakes. The goal is to develop a management plan for the pond that prevents severe algae blooms and improves the water quality over the next 10 years.

“The Maine lakes are a tremendous asset to our state,” said Eric Brown, a high school science teacher who sits on the North Pond Association board of directors. “They are a major part of our natural resources and add greatly to the ecology and economy of our state. Raising the awareness of how connected these lakes are and working to keep them healthy benefits all of central Maine.”

More than $80,000 is available for developing a watershed plan, according to Kelly Marshall, president of the North Pond Association board.

“We really want to be aware and responsible about money we raise for remediation,” Marshall said.

The 7 Lakes Alliance participates in a state program that monitors watercraft using public boat launches to enter or leave lakes. Boats and other watercraft are checked for aquatic plants attached to hulls, motors or propellers. There are many private boat launches, however, so it is not possible to check every craft that takes to the water, according to Sharon Mann of the alliance.

The alliance also works to train volunteers, including Jones, to identify invasive species and survey for new growth in the water.

“What we need is more volunteers,” Mann said. “We need more regular people trained on this stuff.”

Danielle Swain, lake science director at the 7 Lakes Alliance, gathers water samples Thursday on North Pond in Smithfield. Michael G. Seamans/Morning Sentinel

Curly leaf pondweed thrives in nutrient-rich waters with high alkalinity, according to experts. The U.S. Department of Agriculture says it was likely brought to the United States in the mid-1800s, possibly as part of fish-stocking operations. It forms dense mats that inhibit the growth of native plants and can impede recreational activities, including swimming, fishing and boating, according to the USDA.

Curly leaf pondweed is the latest invasive plant to threaten the Belgrade Lakes. Variable leaf milfoil was discovered in Great Meadow Stream in 2009. The milfoil is native to the southeastern and midwestern United States. In 2012, contractors were brought in to try to stop its spread in the Belgrade Lakes.

In 2013, Skowhegan Savings Bank announced a $10,000 donation to the Belgrade Lakes Association Stop Milfoil Campaign. Like curly-leaf pondweed, removing milfoil takes considerable time and can be costly, so community support is important.

Danielle Swain, lake science director at the 7 Lakes Alliance, labels water samples Thursday at a testing location on North Pond in Smithfield. Michael G. Seamans/Morning Sentinel

Pulling pondweed by its roots is the best way to remove it, according to experts, but doing so is not likely to kill it completely because turions, the buds of the plant, become buried in the sediment. As a result, the 7 Lakes Alliance stresses prevention.

“If you see a plant growing toward the surface in May, that’s suspicious. We don’t have a lot of native plants that do that,” Mann said. “Although it looks like it’s contained to the Serpentine (Stream), we need to be prepared for it to be in East (Pond) and North Pond.”

In addition to dealing with the invasive plant, residents and officials have been contending with algae blooms in North Pond.

Danielle Wain, lake science director for the alliance, said the alliance and Colby College have been monitoring North Pond since 2015, but something happened in 2018 to cause severe blooms.

“We’ve collected a lot of data on North Pond,” Wain said, “but there are some gaps in data we plan to fill in the next year or two.”

The blooms are caused by blue-green algae, according to experts. Algae is needed for lake and pond ecosystems, but blue-green algae are harmful. To get a better understanding of why the blooms are happening on North Pond, Wain and her team regularly test water samples with the help of D. Whitney King, a chemistry professor at Colby College.

The samples are taken to King’s lab, where his students help test the water’s clarity, temperature and oxygen, chlorophyll and phosphorus levels. Algae uses phosphorus to bloom, which often comes from runoff and sediment from shorelines.

“It’s a great community collaboration,” King said. “You start to build this team of experts who come up with proactive plans.”

East Pond had similar algae bloom in 2018, which was treated with aluminum sulfate that helped bind the phosphorus.

Wain said North Pond is larger and a similar treatment might not be as effective, but the alliance plans to conduct further research on the treatment.

“They’re all connected. It’s one big Belgrade Lakes watershed,” Wain said. “Everything we do has downstream impacts.”