Invasive plants

Variable milfoil is one of the most common invasive aquatic plants found in Rhode Island’s Department of Environmental Management has amended the freshwater fishing regulations to try to stop the spread of milfoil and other invasives. 


The Westerly Sun

PROVIDENCE — With invasive plants proliferating in almost all of Rhode Island’s fresh water lakes and streams, the Rhode Island Department of Environmental Management has introduced tougher regulations to try to contain them.

The freshwater fishing regulations now include a provision that prohibits the transport of any plants, and even parts of plants, on boats, trailers or fishing gear, and there is now a $100 fine for each violation.

In Rhode Island, more than 100 ponds and lakes and 27 river segments are hosting at least one invasive plant species. The invaders disrupt the habitats of native plants and animals, degrade water quality and impact recreational activities.

Katie DeGoosh-DiMarzio, an environmental analyst with DEM’s Office of Water Resources, monitors water quality and aquatic plant habitats. While information on controlling invasive species has been available on the DEM’s website, DiMarzio said the amendments take the initiative a step further and bring Rhode Island into line with other New England states.

“We’ve been working on it for a while,” she said. “Every other state in New England already has the regulations and we just wanted to come in alignment with other states to make sure that regionally we’re not spreading invasive species from Rhode Island to other states, nor spreading within the state.”

David Gregg, executive director of the Rhode Island Natural History Survey, said the amendments were a necessary response to Rhode Island’s aquatic invasive species situation today.

“I do think it’s positive to see DEM thinking of these things and taking a new direction that reflects the way we’re thinking,” he said.

Comparing Rhode Island’s invasive situation to that of Maine, DiMarzio said the difference is striking.

“To put it in perspective, the state of Maine is 18 times the size of Rhode Island and Maine has under has 50 lakes with invasive plants,” she said. “They have had this type of regulation on the books for, I want to say, 10 years, and so they’ve had a very protective stance on their lakes and ponds, whereas in Rhode Island, we have almost three times as many lakes that have at least one invasive plant than the entire state of Maine. So it’s very widespread here.”

Most aquatic plants can grow from even tiny plant fragments. DiMarzio said that once they were informed of the importance of removing every bit of plant material from their boats and gear, most fishermen would want to comply.

“We need to just make some more efforts in that area, just get people checking around their boat, checking under the trailer, just making sure that’s happening,” she said. “I think it’s a lot easier once people understand that it’s just one little part of the plant. It doesn’t have to have a leaf system, it doesn’t have to have seeds attached. It can just be one part of the plant that travels from their trailer to another lake.”

Environmental police will enforce the new regulations. Gregg said many fishermen would already be accustomed to the stricter laws in neighboring states and therefore should adapt easily to Rhode Island’s stricter regulations.

“I think this will require some adjustment, but a lot of fishermen are faced with much stricter regulations in other states,” he said.

The most common invasive aquatic plants in Rhode Island are variable milfoil and fanwort, but DiMarzio’s team has identified 12 additional plants with invasive potential. One of those is American lotus, which is taking over Westerly’s Chapman Pond.

Gregg said that while in the past, ice and cold temperatures controlled the plant, warmer winters have allowed the lotus to continue to grow and spread.

“When we were doing water lotus, there was just a little patch off to one side,” he said. “It’s native to North America, but it never occurred this far north, because it got frozen and killed off.”

DiMarzio said the lotus patch in the pond was growing at an unprecedented rate.

“The lotus patch has really taken off,” she said. “There’s only a couple of places in the state that have American lotus and it’s a very strange population, smack dab in the middle of Chapman Pond, and it’s grown. I believe it’s over 19 acres. You can go on Google Earth, you can look and you can see the patch growing from one year to the next. It’s just a really aggressive plant.”

The amended regulations require that freshwater fishermen remove all plants, animals and mud from gear and equipment, drain all water-containing devices including motors, bilges and live wells, dry their equipment for 24 hours before using it again and dispose of all bait and fish parts in the trash.

Information on which invasive plants are found in different lakes and ponds, and an interactive map, are available on the DEM website at


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