‘Scary Moment’ As Hydrilla Threatens Area Watershed

The perimeter of East Twin Lake along with a much larger share of West Twin and Shenob Brook are vulnerable to the rapid spread of hydrilla verticillata, a group of top experts agree. If the weed’s spread goes unchecked it could ultimately find its way downstream to the Housatonic River and foul that waterway.

The hydrilla strain, 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 is the first Connecticut lake known to have this strain of the invasive weed. It was discovered near the marina this past summer during a routine monitoring of rare plants organized by the Twin Lakes Association. Rare plants are protected by state law.

Calling this a “scary moment,” Curtis Rand, Salisbury First Selectman, added that lake hopping boaters also threaten Lakeville Lake and Long Pond. As a protective measure, Lakeville Lake was closed to boat launches in September and Long Pond was shut down Oct. 3.

The Twin Lakes are “an incredibly precious resource,” said State Rep. Maria Horn. (She and scientist Gregory Bugbee, facing one another, were part of the water tour Oct. 3, pictured right) Horn added that she hopes whatever steps authorities take to address the problem at Twin Lakes will serve as a model for the rest of the state.

Horn and Rand were among officials and experts who convened at the marina to tour the areas where hydrilla has been found. They met with TLA board members, representatives from Lakeville Lake, the Connecticut Department of Energy and Environmental Protection, Connecticut Agricultural Experiment Station, Natural Diversity Database, Army Corp of Engineers, sustainable solutions company SePRO, and scientists at Northeast Aquatic Research. About 30 people attended.

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. But all lake properties with shoreline are vulnerable, said George Knoeklein, limnologist at NEAR. The invasive weed spreads largely through fragmentation: pieces of the plant being separated and floating or being transported to other areas. The invasive is best identified as a five-leaf (or more) plant, which distinguishes it from the native elodea.

A critical challenge surfaced when officials at the two-hour gathering 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 different missions. There is no single entity calling the shots on hydrilla.

That authority is “noticeably missing,” said Ellie Clark, who gathers and coordinates information for DEEP, which has no specific lakes program. “This is the first we’ve seen it in a lake,” said Gregory Bugbee, a scientist at CAES. “We didn’t know it could move.” 

After the meeting, Rep. Horn said her first call was going to be to DEEP Commissioner Katie S. Dykes to discuss designating a point person responsible for dealing with hydrilla. She also 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. The TLA estimates it will spend about $50,000 monitoring, hand pulling plants, treating the Marina with the herbicide ProcellaCOR, and preparing reports for the state.

There are signs that a heavy dose of herbicide applied in September are working. “The plant appears to have kind of shut down and is just sitting there,” said Mark Heilman director of aquatic technology at SePRO. He saw evidence that the treated hydrilla was dying. But there is no guarantee it won’t still spread.

On a boat tour north of the marina, where rare species are known to exist and which has been off limits for treatment, experts pointed to healthy hydrilla sprouts. The TLA is going to petition for treatment in that area next year. Given the rare plants in that section, and the lack of a single authority, this will not be an easy process. Part of DEEP is setup specifically to safeguard rare plants. That part will likely object, or require copious data, before approving treatment.

The TLA position boils down to this: There is no time to waste; we can risk harming some rare plants now or risk losing much of the watershed later, including those sections of Twin Lakes with rare plants.

Photos by Dan Kadlec

TLA board member Russ Conklin leads the discussion at the marina

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