Officials aim to rid Bow’s Turee Pond of milfoil

  • A piece of milfoil washed up on the boat launch at Turee Pond in Bow on Monday, May 16, 2016. NICK STOICO / Monitor staff

  • A sign asks boaters to clean and drain their boats before launching at Turee Pond in Bow on Monday, May 16, 2016. NICK STOICO / Monitor staff

  • A sign asks boaters to clean and drain their boats before launching at Turee Pond in Bow on Monday, May 16, 2016. NICK STOICO / Monitor staff

  • A view of Turee Pond from the boat launch facing northwest. NICK STOICO / Monitor staff

Monitor staff
Tuesday, May 17, 2016

Sandra Crystall was paddling her canoe on Turee Pond in Bow last summer when she noticed a collection of bushy green plants sprouting up just below the surface.

It didn’t take more than a moment for Crystall, who works for the Department of Environmental Services monitoring and assessing New Hampshire wetlands, to suspect the plant was milfoil, an invasive species that has spread to lakes and ponds across the state over several years.

She made a call to her colleague Amy Smagula, coordinator of DES’s Exotic Species Program, and by the end of June, Turee Pond was added to the list of 84 water bodies infested with invasive species in the state.

This summer DES will begin a treatment plan to rid the pond of milfoil, but don’t expect it all to be gone by Labor Day. It will likely take a few years to completely eradicate the plant’s expanding population.

Smagula estimates milfoil has been in Turee Pond for the last four or five years. In that time, milfoil has spread around the 47-acre pond along the shoreline in a big circle. There are about 34 acres of the plant in Turee Pond, Smagula said, well beyond the scope of sending divers down to uproot the plants. Only until the majority is killed off by an herbicide can the rest be removed by hand.

“We’ll implement this integrated plant management technique and then continue with thorough monitoring,” Smagula said.

The herbicide, tiny clay particles known by its brand name Navigate, will be applied to the infested areas around the pond June 2. The remedy acts as a growth hormone, expanding the plants faster than the material can reproduce itself causing it break down and sink to the bottom. It effectively kills the whole plant, leaving no live fragments that could otherwise take root and continue to spread.

A few weeks after the herbicide is applied, divers will go in to remove regrown or newly grown milfoil.

“I know that there are other associations and lakes that want to stay away from chemical treatment, but I think based on what I have heard and the extent of the milfoil covering Turee Pond, that this may be the only choice,” said Crystall, chairwoman of the Bow Conservation Commission.

Smagula said the herbicide will not kill other plants or animals. Boating and swimming will restricted for one day and there will be an odor coming from the pond for a couple of days following application.

DES has been successful in completely removing milfoil and other invasive species from water bodies, but only when it has been found in its early stages as a small patch. The state’s largest bodies, such as Lake Winnipesaukee and Squam Lake, are continually managed but will not be completely rid of milfoil – or other invasive species – for many years, if ever.

“The earlier it is identified the better,” Smagula said. “That is why we survey as much as possible.”

Turee Pond was found to be infested with variable milfoil, the most common type found in New Hampshire waters. It grows rapidly, as much as one inch per day in the summer, and can reach 15 feet in length.

Milfoil’s rate of reproduction is almost as fast as its growth. All it takes is a couple inches of its stem to settle in the pond’s floor and take root. Smagula hopes to stop the milfoil’s expansion before it reaches the wetlands surrounding Turee Pond.

“It can be really tough to get it out of there,” she said.

The first year of the plan will cost about $10,000, and will be covered by DES. In the plan’s ensuing years, DES will cover up to 50 percent of the cost matched with the town.

The pond will be re-evaluated in 2017, but after the first year, Smagula said, the cost typically goes down because most of the species is gone.

Milfoil is not the only invasive species that has been found in Turee Pond. Small strands of phragmites, also known as the common reed, have been identified in the pond’s south end but should be easier to remove.

The spread of invasive water plants has become a top concern in New Hampshire, where lakes and ponds are a major attraction for tourism. Last year, the state spent about $1.1 million combating the spread of invasive species.

In the State House, lawmakers are pushing a bill that would make transferring aquatic plants and weeds to state water bodies a ticketed offense. Milfoil is most commonly spread by latching onto boats and trailers in one lake and then dropped in another. That is why milfoil commonly originates near a boat launch before spreading to the rest of the lake.

Signs are posted around launch sites across the state, including Turee Pond, asking boaters to wash, drain and dry their boats and trailers before going into the water.

Since milfoil was discovered in Turee Pond last year, Bow has joined the New Hampshire Lakes Association’s lake host program. Beginning this summer, lake hosts will monitor the Turee Pond launch on weekends and holidays making sure boats are clean before entering the water.

“We want to make sure the enjoyment of this pond can continue,” said Stacy Luke of the Merrimack County Conservation District.

(Nick Stoico can be reached at 369-3309, nstoico@cmonitor.com or on Twitter @NickStoico.)