The Maine Department of Environmental Protection and the Volunteer Lake Monitoring Program (NLMP) confirmed on Sept. 24 that a plant discovered growing in Damariscotta Lake in Jefferson is an invasive plant species called hydrilla verticillata. “Everyone who lives on the lake has been fearing something like this for years,” Damariscotta Lake Watershed Association Director Al Railsback said.
The hydrilla was discovered by DLWA volunteer Dick Butterfield, while he was canoeing the west shore of the lake off Hemlock Park Road on Sept. 21. Butterfield received invasive plant identification training last summer at a DLWA sponsored two-day workshop. “This is the first time an invasive plant species has been discovered by a trained volunteer,” DEP biologist John McPhedran said.
DLWA volunteers have twice stopped the invasive plant Fanwart from entering the lake on boat trailers in the past two years.
The hydrilla was discovered growing in a small lagoon, located on the former William Judd, Sr. property (now owned by his son William, and four daughters) off of Sachem Drive in Jefferson. “Hydrilla grows an inch a day, and without predators overtakes native lake habitats, shading and out competing ecologically valuable plants. The Dense infestations can alter water chemistry and oxygen levels,” a press release from DEP stated. Paul Gregory of DEP called hydrilla “the most aggressive invasive aquatic plant in North America.”
DLWA trained volunteers will be conducting an extensive survey of the area, to determine if the plant has spread outside of the lagoon. It is not very deep, but the hydrilla “is firmly entrenched. It has been there awhile. It is the worst of the bunch. It can go 50 feet deep, can propagate three ways, and over winters,” Railsback said.
Hydrilla is anchored to the bottom by tubers. Broken off plant segments take root. The plant flowers and forms a winter bud that falls off and can float off, and then sink to the bottom where a new shoot takes root. “Hydrilla and Eurasian water milfoil are the worst two invasive plant species. Hydrilla is harder to treat because of its tubers. It is a little harder to knock back, because there are three ways it can reproduce,” McPhedran said.
DEP responded quickly after receiving a plant sample on Sept.22. They positively identified it on Sept. 23, and were on scene Sept. 24, installing a fragment net to prevent the invasive plant from spreading. DEP biologist John McPhedran said the hydrilla “is growing densely” in the lagoon, which he estimates to be about a third of an acre in size.
The small lagoon has a berm (beaver dam) on the east side, which has partially eroded. No hydrilla was found by DEP in the lake outside this berm, although they found a small plant fragment floating in the cove directly outside the lagoon. The lagoon has a larger opening to the lake on the north side of the property. The hydrilla “is not contained strictly to the lagoon. There is some growing out beyond there a little bit. This is a well-established colony. Whether it has popularized other areas of the lake, we don’t know,” McPhedran said.
Three officials from DEP were on scene Thursday, installing a 50-foot net across the lagoon opening on the north side, to prevent the further spread of fragments out of the cove. DEP workers were back on scene on Sept. 29 to further curtail the spread of the invasive plant, by installing a net over the smaller mouth of the lagoon. Divers installed a benthic barrier, made of 6mil plastic and weighted down with rebar in the cove, directly outside the lagoon where hydrilla was found.
“It smothers the plants by not allowing light in, but it will not kill the tubers,” Paul Gregory said. “It has set up camp a goodly amount of time. Hand removal will not work” Gregory added because “if fragments escape they can make a new population.”
DEP’s current plans are to assess the entire lake situation before making a decision on their next course of action. Gregory said herbicides “are in our toolbox” but DEP is not making any decisions until the lake has been fully surveyed. “Right now we are collecting evidence. Monitoring is important right now. The positive thing is we have a great monitoring effort with trained plant patrollers. We need vigilant eyes checking out the lake for now,” Gregory said.
Invasive plants are spread from lake to lake on boat trailers, boats, equipment and fishing gear. They are also inadvertently spread by purposely introducing non-native plants to a water body, as the invasive plant can piggy-back in the sediment of other plants. Dumping aquarium contents into a water body is another source of contamination. According to DEP officials, the tubers of the hydrilla can lay dormant for years. Hydrilla is an aquarium plant and is used in water gardens. DEP officials said that they have discovered hydrilla hitch-hiking with water plants being sold on two different occasions.
There are 31 water bodies, out of 5,785 ponds and lakes, in Maine that have been identified as harboring an invasive plant species. Pickerel Pond in Limerick is the only other water body in Maine where hydrilla has been positively identified. The 50-acre pond is being treated with the herbicide fluridion. DEP’s efforts have not eliminated the invasive species from the pond, but have greatly reduced it. “It has not spread to nearby water bodies,” McPhedran said.
McPhedran said because the hydrilla appears to be contained to a small area, DEP would probably attack the Damariscotta Lake hydrilla by installing a bottom barrier to smother it and prevent it from getting light. “No matter what the infestation is, it will take time,” McPhedran added.
“Every invasive species infestation, no matter how aggressive, starts small. Early detection by Mr. Butterfield gives us the upper hand, enabling rapid deployment of trained personnel, equipment and other resources to contain this hydrilla population. That is our immediate objective,” Paul Gregory, and environmental specialist for the DEP commented.
DEP officials collected hydrilla and pink water lily samples from the cove. The pink water lily is a non-native species to Maine. DEP officials speculated that the hydrilla could have piggybacked in sediment around the pink lily plant.
William Judd, of Damariscotta, and his four sisters inherited the property from their father, who purchased the property in 1959. The berm of the walled in lagoon, which the family calls the swamp, was in place when William Judd, Sr. purchased the property. “I don’t now what created the berm. One end has opened up over the years by wave and ice action,” Judd said.
Of the pink lilies in the cove, Judd said, “I planted them many, many years ago, back in my youth. I got them from Davis Stream (Damariscotta Lake contributory) almost 50 years ago.” Judd said he never noticed the invasive plant hydrilla in the cove. “I didn’t know about it until Paul Gregory of the DEP called on Wednesday. I have no idea how it got there.”
Judd said the cove has had an active beaver colony it in recent years. While the beaver were present, the “number of water lilies was greatly diminished. I think the beavers ate their tasty tubers. The beaver were not around this year and the lilies were beautiful,” Judd gave as a possible explanation of the bloom in the hydrilla this summer.
Hydrilla is referred to as the perfect weed. The submersed plant grows in a variety of habitats, in currents and tolerates salinities up to 10 parts per thousand. The non-indigenous invasive plant found in Damariscotta Lake has a whorl of five leaves off its main stem, which distinguishes it from native aquatic plants that have a whorl of three leaves. The leaves are finely toothed and the undersides of the leaves may have one or more spines on them. The white tubers of the plant look like small bean sprouts. The plant completely dies back in the winter, but sprouts from over-wintering rhizomes, tubers and turions in the spring.
DLWA called an emergency meeting of volunteers on Saturday morning to explain the situation and give instructions for a stepped up search. DLWA AmeriCorps volunteer Alice Phillips showed slides of monoecious hydrilla and had samples of both native plants and hydrilla to show volunteers the difference. Each volunteer was assigned a section of the narrows and given floating markers with an anchor to mark any vegetation they suspected of being hydrilla. No hydrilla was found in the narrows, south of the infestation site, by volunteers over the weekend.
Four areas of the lake, including the bay area north of the site were surveyed professionally by aquatic ecologist Roberta Hill earlier in the summer. DLWA has contracted with Hill yearly for over five years to survey the lake near the State boat launch, the Vannah Road launch, Town Line launch and the Davis Stream.
