Urgent hydrilla response on local, state, federal level

SALISBURY — Despite being shocked and weakened by a heavy dose of herbicide in September, patches of invasive hydrilla have set down roots at East Twin Lake and will continue to pose a serious threat to the Twin Lakes watershed and other bodies of water if aggressive and costly follow-up treatments, expected to take several years, fail to eradicate it.

“Will we be able to kill it? I don’t know, but I think we have a darn good chance,” said Twin Lakes Association (TLA) board member Russ Conklin. “You don’t want to be in a position where you’re managing the hydrilla. You have to kill it. Managing it means you couldn’t control it.”

The urgency in stopping the noxious weed from migrating has triggered a major response effort on a local, state and federal level. 

On Oct. 3, a contingent of about 30 people gathered at the marina just a short distance from the boat launch where thick mats of stringy, green hydrilla are thriving. They were discovered in an area of about four acres earlier this summer during routine monitoring of rare plants, which are protected by state law. 

Twin Lakes board members were joined at the forum by representatives of the Lake Wononscopomuc Association, State Representative Maria Horn (D-64), Salisbury First Selectman Curtis Rand, scientists at Northeast Aquatic Research, and representatives from the state Department of Energy and Environmental Protection (DEEP), the U.S. Army Corp of Engineers, the Connecticut Agricultural Experiment Station (CAES), Natural Diversity Data Base and the sustainable solutions company SePRO, among others.

Several weeks earlier, infestations in a four-acre area around the marina had been chemically treated with the herbicide ProcellaCOR, but because the treatment took place late in the season due to a delay in the state permitting process, it merely served as a stop-gap measure to help the tall shoots of hydrilla decompose so boats and docks don’t spread fragments around as they are removed from the marina for the season.

“The ProcellaCOR did what it was supposed to do. We were looking for something to take out the standing crops because the concern was that any fragments can take root,” and spread, Conklin explained. While the wounded weeds will naturally decompose over winter, the roots remain unaffected and will likely resprout, he said.

“As it stood when we went out there, it was barely at all affected by the treatment. That’s not a good sign,” but we may be jumping to conclusions because this product may take a longer time to affect the hydrilla, said Greg Bugbee, associate scientist with the State office of Invasive Species at the CAES and principal investigator for its Invasive Aquatic Plant Program.

 “Next year we have to monitor and treat it again at the proper time,” Conklin explained, using a different herbicide, fluoridone, which will require a modification of the TLA’s treatment permits and series of timed applications applied earlier in the season.

The chemical fluoridone, he said, comes in a crystalline form and sinks into the mud. The chemical is slowly released and absorbed by targeted hydrilla via a regimen of spot treatment.

In order to avoid a repeat delay in obtaining approvals, Horn, who took a boat tour of the areas where hydrilla is growing, said she is calling for the appointment of a point person at the state level, or possibly a lakes commission, to speed up the process.

“It became clear at the meeting that there are a lot of good, knowledgeable people at DEEP, but this is an urgent issue that can’t wait for various groups to make a decision,” said Horn. 

A critical challenge surfaced during the two-hour gathering when officials were asked where hydrilla in the lake sits on the state’s list of priorities.

“With virtually every relevant state and local office represented, no one ventured an answer because the way the state government is organized remediation falls into the hands of multiple offices with diverse missions. There is no single entity calling the shots on hydrilla,” the TLA reported the next day in a newsletter summarizing the meeting.

That authority is “noticeably missing,” said Ellie Clark, who gathers and coordinates information for DEEP, which has no specific lakes program.

The TLA estimated it will spend about $50,000 monitoring, hand pulling plants, treating the marina with herbicides and preparing reports and permits for the state.

 Horn, who described Twin Lakes as “an incredibly precious resource,” said she would push for state funding to help with the costs of treating for hydrilla but that the state would not be able to shoulder the full financial burden, so other sources of funding will be needed.

As a protective measure, nearby Lake Wononscopomuc was closed to boat launches in September, and Long Pond was shut down on Oct. 3. 

A hard strain to contain

An aggressive, robust variant of hydrilla verticillata, also known as water thyme, was discovered in 2016 in the Connecticut River, which is now choked with unwanted growth in many areas.

East Twin Lake was the first lake in the state known to have this strain of the invasive weed when it was discovered there this summer. But TLA board member Conklin said he believes the invasive, five-leaf plant with its long, slender stems that float near the water’s surface had been growing in plain sight for several years, disguised as elodea, a similar-looking native plant.

Of particular concern is that the perimeter of East Twin, along with a much larger share of West Twin and the ecologically sensitive Shenob Brook are vulnerable to infestation, as is the Housatonic River downstream, which feeds into Lake Lillinonah, Lake Zoar, Candlewood Lake and Squantz Pond.

Since hydrilla’s discovery in East Twin during a routine monitoring of rare plants organized by the TLA, the Connecticut River variant has also been confirmed at three other lakes in Connecticut:  Amos Lake in Preston, Lake Pocotopaug in East Hampton and Middle Bolton Lake in Vernon.

Hydrilla thrives in water up to 20 feet deep, which puts the north end of East Twin and virtually all of West Twin at greatest risk, according to TLA officials. But all lake properties with shoreline are vulnerable, said George Knoecklein, TLA’s consulting limnologist.

Mark Heilman, director of aquatic technology at SePRO, a sustainable solutions company, said he saw signs that the heavy dose of ProcellaCOR applied in September is working and that the treated hydrilla was dying. But there is no guarantee that it won’t still spread.

CAES’s Bugbee said there was “a lot of good” that came out of the recent herbicide treatment “from the standpoint that many desirable native species that were not affected, such as pondweed and eelgrass. And right now the Eurasian milfoil is gone. It was a very big problem in the marina.”

“We had a great turnout from such a cross-functional group of stakeholders,” said Grant Bogle, TLA president, reflecting on the Oct. 3 meeting.

 “Everyone understands the urgency of moving aggressively now to keep the hydrilla in Twin Lakes in check,” said Bogle who said his association aims to be transparent throughout the process and “committed to using the best science available” as a guide.