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NUISANCE
WEEDS IN QUADDICK LAKE
For
many years excessive weed growth threatened to disrupt the
ecological and recreational balance maintained within Quaddick Lake.
The encroachment of nuisance vegetation, especially non-native species
like variable watermilfoil (Myriophyllum heterophyllum), fanwort
(Cabomba caroliniana) and bladderwort (Utricularia) was seriously
hindering the spread of wildlife as well as human access and enjoyment
of the lake. The ever-present trend of continued development and
"cultural eutrophication" emphasized the importance of a well-rounded
plan to manage Quaddick Lake.
Over the years, several
methods of weed control have been attempted sporadically but, in order
to regulate and control the weed growth, an ongoing
management program was required. In 2007, the Quaddick Lake Association
created a Lake Management Committee to focus on comprehensively
evaluating available techniques to address this issue and then to
educate the community and Association so the membership can determine
the best method to use to control the problematic growth as an annual
effort. Nuisance
Aquatic Vegetation Management (1.8 mb pdf)
is a guidebook produced by the State of Connecticut Department of
Environmental Protection and Pesticides Management Program, regarding
the invasive vegetation issues that affect our lake.
One
of the primary charters of the Association's Lake Management Committee
is to ensure that residents within the watershed area are properly
informed about the factors that contribute to weed growth and the
options that are viable to control the growth. This website is the
primary vehicle to deliver this information. Review some Do's
and Don'ts
for lake-front Residents.
TREATMENT
OPTIONS
In
2001 and again in 2007/08, Aquatic Control Technology, Inc. was
contracted to complete a
diagnostic assessment of the exotic, invasive vegetation in the lake.
The methods determined as viable to effectively control this vegetation
in Quaddick Lake were drawdowns, hydro-raking and/or chemical
treatments. You can read the entire original report
here (5.6 mb pdf).
DRAWDOWN
A
drawdown is lowering the water level in the winter until the exposed
bottom freezes, to kill roots of vegetative places and susceptible
seeds of certain rooted aquatic plant species.
Drawdowns have been used on Quaddick Lake in the past for rooted plant
control, to prevent ice damage and to allow for repair of docks and
shoreline areas. View
an example of the 3-4 foot drawdown.
Following
the Quaddick Lake Association meeting on August 27th 2006, it was
determined that the first step in the lake management
program will be to lower the lake's water level (drawdown) annually.
Divers will
inspect the drain pipe's grate to make
sure it is clear of debris each September and then Rawson
Manufacturing will begin generating electricity by drawing water
through the
pipe and over the Red Bridge Dam in early October. Under normal weather
conditions, this should lower the
water level of the lake, until the lake is down about 5 feet in
January.
The lake
should
freeze in early January to an average thickness of 8-10 inches. About
2/3rds of Upper Quaddick will experience significant contact between
the
ice and the weeds on the bottom of the lake. After sustaining a period
of 30 days of surface contact, the ice causes significant damage to
the root systems of the weeds within the contact area.
Rawson
Manufacturing will stop drawing water from the lake in late March. With
good timing and some luck, the
snow melting and periodic rains will quickly raise the water
level back to its normal condition. This forces the ice off the
surface, thus uprooting the weeds frozen in the ice. This also allows
for the lake to stay cooler for a longer period of time. The cooler
water holds the initial new growth at bay and delays the surge of weeds
until later in the summer.
HYDRO-RAKING
Mechanical
raking (Hydro-Raking) is a widely used and effective technique for area
selective removal of nuisance, rooted vegetation. In some situations
the Hydro-Rake is also used to clear accumulations of unconsolidated
bottom debris (i.e. decaying leaves, peat, muck). The Hydro-Rake can
best be described as a floating barge upon which is mounted a backhoe
with several different size and functioning rake attachments. The
Hydro-Rake is powered by a Diesel engine which drives the hydraulically
operated paddle wheel propulsion system and back-hoe functions. The
Hydro-Rake can operate in water as shallow as 1.0 -1.5 feet and can
remove nuisance vegetation and bottom debris from variable water depths
as shallow as a few inches to a maximum depth of 12 feet. Duration of
nuisance plant control varies, but is typically "summer long" for
species such as water milfoil (Myriophyllum sp.) to 2-3 years or longer
for plants with well developed root systems (i.e. waterlilies,
cattails, etc.)
The
Hydro-Rake works from the water and can therefore access coves and
shoreline areas otherwise inaccessible to conventional machinery.
View the Hydro-Rake.
Damage to valuable shoreline habitat and waterfront property are
avoided with the Hydro-Rake. The Hydro-Rake deposits each rake full
(maximum 500 lbs.) of material directly on-shore. Upland disposal of
Hydro-Raked material will be handled by the customer in conjunction
with
the Lake Association and taken to a central collection point where it
will be disposed of by the Town of Thompson.
When deemed necessary, the
Quaddick Lake Association can make arrangements with Aquatic
Control Technologies to Hydro-Rake beachfronts and shorelines for
lakefront homeowners at a discounted rate. In extreme cases, the
Association may cover the costs of delivery of the machine ($1000) but
homeowners are required to contract ACT individually by completing and
submitting a sign-up form.
The
Hydro-Rake deposits each rake full of material directly on-shore
and then permanent disposal of the Hydro-Raked material is handled
by the homeowner in conjunction with the Lake Association and taken to
central collection points around the lake where it is picked up
and disposed of by the Town.
CHEMICAL
TREATMENT
The only herbicide that
is effective against fanwort
is
fluridone, commonly called Sonar, and is only available from only one
manufacturer. The use of this product has been used to resolve the
overgrowth of the
fanwort. The good news is that Sonar is harmless to fish, animals and
humans. It is used to treat drinking water reservoirs. EPA permissible
limits in drinking water are about three times greater than the
concentration needed to kill the weeds. It is very effective against
fanwort if necessary concentrations are maintained for approximately
six weeks…..not an easy task given the flow rate of water
through Quaddick, but doable if rains are not too heavy. It also
greatly reduces the milfoil and somewhat reduces bladderwort for the
first year. Treatment is guaranteed for two years for the
fanwort, with the expectation that it would be three years or more
before fanwort was a problem again. The bad news is that treating upper
Quaddick alone costs between 100,000 and $150,000. Adding lower
Quaddick, which occasionally sees fanwort and the other weeds in
shallower areas, raises the cost to about $175,000. The view of the
Lake Management committee is that, if herbicide treatment is required,
it is best
to treat both upper and lower sections of the lake. If the problem is
kept in check by re-treatment before things get out of hand as they are
now, it should not be necessary to spend this amount of money at one
time
again. Ongoing
maintenance over 10 years will average about $36,000 per year.
In May
of 2007, the State of Connecticut awarded the Town of Thompson a bond
for $200,000 to be used for Chemical Treatment of Quaddick Lake. The
disbursement of the funds is be at the discretion of the Board of
Directors and is used to offset the costs of chemical treatment
as well as the purchase and maintenance of water quality monitoring
devices.
Chemical
treatments are
conducted annually. The reports are available by clicking a link
below.
2008 Treatment Areas
Revised July 2009 Report
Survey 2009 Year-End Report
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