http://pressherald.mainetoday.com/news/york/050628hydrilla.shtml
Portland Press Herald
June 28, 2005
State works to stem spread of hydrilla
in Limerick pond
By SETH HARKNESS, Portland Press Herald Writer
LIMERICK — They may never be able to eradicate the invasive
plant that has worked its way from Asia to Pickerel Pond, but
state officials say they intend to stop it from spreading further.
The 48-acre pond off Route 11 has the unfortunate distinction
of being the only body of water in Maine found to contain hydrilla,
a particularly aggressive aquatic nuisance that chokes waterways
throughout the Southeast and Mid-Atlantic and is moving north.
After first documenting hydrilla in Pickerel Pond in 2002,
the state Department of Environmental Protection started treating
the pond with small doses of herbicide. At the time, the plant
covered nearly 70 percent of the pond. Looking down into the
water was like staring at "submerged Astroturf," said
Paul Gregory, an environmental specialist with the DEP's invasive-species
program.
Three years later, hydrilla persists in Pickerel Pond and the
chemical applications continue. On Monday, a Massachusetts contractor
skimmed around the pond in an airboat, distributing a little
more than two gallons of herbicide.
The plant has been subdued to the point where it cannot be
seen from above the water, so the DEP had to send divers into
the pond last week to determine whether it was still present.
"The goal is to knock it back by 95 percent each year,"
Gregory said. "Now, it's difficult to find a plant. We
used to throw in rakes and pull it up by the fistful."
Still, at current doses of about eight parts per billion, it
is unlikely the herbicide will kill the hydrilla completely,
Gregory said, and the DEP has permits to continue treating Pickerel
Pond for another five years.
The primary goal is to prevent the plant, originally brought
to North America from Sri Lanka and South Korea 40 years ago
for use in aquariums, from taking root in more of Maine's relatively
unsullied waters.
Of Maine's 6,000 ponds and lakes, 25 are infested with some
sort of invasive plant. Nearly everywhere else in New England,
the situation is worse, which Gregory attributed to greater
boat traffic.
"In many ways this is a social problem. (Invasives) follow
people," he said. "In Connecticut, the assumption
is, all bodies of water have four or more invasive species growing
in them."
On Monday, the battle to contain hydrilla in Maine was being
waged from an 18-foot airboat piloted by Gerald Smith, an aquatic
biologist and president of a Massachusetts company that does
contract work controlling aquatic nuisances.
Smith and an assistant made orderly circles around the pond
in their high-speed boat. They used a
highly accurate global positioning system to chart their course
as they applied a minute dose of fluridone, a herbicide that
costs $1,500 a gallon and kills hydrilla without affecting people
or fish.
Though hydrilla has been found in only five bodies of water
in New England, Smith said the noxious weed has overtaken many
lakes in Florida, where the state spends $20 million a year
just trying to knock back hydrilla and keep waters passable.
Like other invasives, hydrilla crowds out native plants, eliminates
fish habitat and alters the water chemistry of a lake or pond.
No other aquatic nuisance has the reputation for doing so as
aggressively.
"If this plant gets out, there's nothing like it in terms
of habitat destruction or incredible density on the water's
surface," Smith said. "Even milfoil pales in comparison
to hydrilla."
A DEP notice at the Pickerel Pond boat launch advised against
swimming and boating on Monday, not because the herbicide posed
a danger but to keep the pond clear for the applicators, according
to Gregory. The notice also advised people not to irrigate with
pond water this summer because the herbicide could damage plants.
Some Pickerel Pond fans said they welcomed the DEP's efforts.
Outside of his family's pond-front cabin, John Choate said
he had seen ponds overtaken by invasive plants near his home
in Taunton, Mass., and was pleased that the state was trying
to stay ahead of the problem in Limerick.
"It's a beautiful pond and I'd hate to see it go to waste,"
he said.
Staff Writer Seth Harkness can be contacted at 282-8225 or
at: sharkness@pressherald.comTo top of page
Copyright © 2005 Blethen Maine Newspapers Inc.
