The Hydrilla Menace: Ripples of hope along a ravaged river

“If we wait five years, we will be able to walk across the river if it’s left
unchecked.” — Bob Petzold, president of Petzold’s Marine Center, on the urgency of halting hydrilla’s rampant spread.

This is the second of a series about invasive aquatic hydrilla and its growing threat to waterbodies and communities in Northwest Connecticut.

CHESTER, Conn. — Bob Petzold has spent the past few summers mowing his marina’s boat slips.

Thick, verdant green mats of notoriously troublesome hydrilla have made it impossible for vessels to enter or exit the channel unless he and his crew mechanically chop, gather and haul away massive piles of the invasive weed, which has clogged the Chester Boat Basin, one of two marinas he owns and operates on the Connecticut River.

Petzold knows that in doing so, he raises the risk of spreading hydrilla fragments that will drift away and repopulate elsewhere. But he has little choice, he said, if his four-generation, family-owned and operated business is to remain afloat.

“It’s a necessary evil,” he said. And an expensive one at that.

“We spend thousands of dollars on outside contractors and we have our own staff remediating it just to keep the channel open,” Petzold explained during an early September visit to his marina.

“When the water is clear, you can almost watch the hydrilla grow. If we wait five years, we will be able to walk across the river if it’s left unchecked.”

Bob Petzold, owner of the Chester Boat Basin on the Connecticut River, points to an area clogged with thick mats of hydrilla prior to a test application of an aquatic herbicide by the U.S. Army Corps of Engineers this summer. Two of his marinas are among five demonstration sites in the Connecticut River Watershed selected for hydrilla research.Photo by Debra A. Aleksinas

The strain of hydrilla in the Connecticut River has been an ongoing concern since its discovery in 2016. It is considered genetically distinct from other known hydrilla populations in the world, and as such, there is limited information available to aid in the development of management strategies to limit its explosive spread.

Kayaks can’t pass through it. Boat motors get tangled by its long strands and stall. Coveted fishing holes have been abandoned by anglers, and swimmers won’t swim in it. Scientists are also addressing concerns about hydrilla’s threat to the ecosystem, including osprey and bald eagles. They fear that the Connecticut River strain harbors cyanobacteria, which produces a neurotoxin deadly to birds of prey.

Rhea Drozenko, river steward for the Connecticut River Conservancy, pointed to the Mattabesset River as an example of hydrilla’s explosive nature. “It created this huge mat, and some native plants couldn’t stand a chance. It created a sea of hydrilla.”
Fortunately for Petzold, and others who own businesses or real estate, enjoy recreational activities or cherish the 200-mile-long river’s aesthetics and ecology, hope is on the horizon.

Petzold’s two marinas, Chester Boat Basin and Portland Boat Works, are among five sites in the Connecticut River Watershed selected for testing of aquatic herbicides this summer as part of an ongoing hydrilla research project by the U.S. Army Corps of Engineers (USACE).

Other test sites include Chapman Pond in East Haddam, Keeney Cove in Glastonbury and Selden Cove in Lyme.
Scientists hope to reduce and control hydrilla, while protecting plants, fish and the long-term health of the river, as well as its $1 billion-plus contribution to Connecticut’s economy.

The results of that research could also bring a sigh of relief inland, where 10 lakes, so far, have been identified as hosts to hydrilla, which is spread between bodies of water primarily by unsuspecting boat owners.

East Twin Lake in Salisbury was the first lake outside of the Connecticut River watershed to identify an infestation late last summer. That number is expected to rise once the Connecticut Agricultural Experiment Station (CAES) concludes its planned inspections of every state-owned boat launch throughout Connecticut.

Invasive aquatic plants in the Connecticut River.Connecticut Agricultural Experiment Station

$100 million in federal funding

In 2021, Sen. Richard Blumenthal (D-Conn.), announced that he is leading an effort to secure $100 million over four years in federal funding for a multistate effort to control hydrilla in the Connecticut River Watershed, and in June, he announced $5 million in federal funding for the USACE demonstration project.

“Senator Blumenthal was here. He pledged his support in getting government funding for this continual battle,” noted Petzold, who referred to hydrilla as “the biggest threat beyond our control” in the nearly 80-year history of his family business.

The funds will also support other goals including preventing hydrilla from spreading into coves, tributaries and inland waters, improving surveillance and detecting new infestations early and responding quickly to control and eradicate new infestations.

In addition, the Connecticut Department of Energy and Environmental Protection (DEEP), through the State Aquatic Invasive Species (AIS) Grant Program, made $500,000 available to municipalities, state agencies and nonprofit organizations to reduce impacts of aquatic species, including hydrilla, on inland waters.

Connecticut awarded approximately $952,700 to 46 projects statewide during the first three years of the AIS Grant Program.

Hope is on the horizon

As stakeholders await the results of the USACE’s demonstration project, already there are encouraging signs.

Petzold pointed to the gently rippling water surrounding the boat basin, which he said had not been that clear during peak boating season for several years. Around the slips, strands of sickly-looking hydrilla floated among dead leaves, victims of herbicidal dosing.

He credited the bipartisan support of lawmakers on the local, state and federal level for going “above and beyond” in supporting and communicating with stakeholders.

“In my mind, it’s made a world of difference. We’ll see what the test studies reveal, but it seems like it is doing the trick here, at least in the basin,” said the marina owner, who credited DEEP and USACE for working together effectively and keeping stakeholders in the loop and respond to their concerns.

“At this point I guess there’s no cure for it, but we have to figure out a way to stop it from spreading and growing as best we can.”
Beth Rye of Chester, who owns two vessels, a 20-foot Grady-White and 35-foot Viking, was ecstatic about being able to navigate in and out of the slips without her boats’ props getting snarled in hydrilla. “It’s gone!” she announced with glee.

Relief for some raises red flags for others, noted Drozenko, particularly when aquatic herbicides are involved.

“There has been a lot of concern about the use of herbicidal treatments, especially in very fragile, ecologically sensitive zones.”

Lakes and ponds, she said, are easier than flowing rivers to treat, as they are more contained and especially if the infestation is caught early, as in Salisbury’s East Twin Lake.

“Whereas if hydrilla moves into the Housatonic River,” the river steward cautioned, ‘it will have the same impact as in our river.”
Coming next: What’s at stake for Salisbury’s six lakes in 2025 and beyond.