Water Chestnut Eradication
in the
Alewife Brook Watershed
Inception - Stewart Sanders led me on a kayak tour from Little Pond to the
Mystic River and back late fall of 1999. Along the way I noted several patches
of water chestnuts which appeared small enough to remove by hand. I decided
to attempt a three-year eradication of this weed in the Alewife Brook watershed
if all permits and permissions could be obtained.
Current Conditions - Small numbers of plants were seen in Little Pond, Little
River, and Perch Pond. Large mats existed in Blair Pond and Alewife Brook.
Cities where harvesting is planned include Arlington, Belmont, Cambridge,
and Somerville.
Trapa natans - European water chestnut served as a food source in some early
human societies. In Massachusetts it is an introduced, invasive species classified
as a noxious weed in the 1990 agriculture code. Large mats of the plant can
completely choke light from a waterbody and halt all navigation.
Proposal - During the growing seasons of a 36-month period beginning mid-2000,
volunteers will use hand methods to remove all water chestnut plants found
in the Alewife watershed. Monthly patrols will attempt to ensure no new viable
seeds have time to form. A three-year time is required because seed from
earlier years may remain viable at least this long. Yearly checkups after
this would be advised.
Methods - Harvesting will take place entirely from non-motorized craft such
as canoes and kayaks. Hand pulling will be the main method, but hand tools
may be used in deeper water to snag the stem as near the bottom as possible.
A potato rake has been recommended. The plants will be collected in plastic
recycling bins for hand transport over any fragile bank area.
Disposal - The City of Cambridge has agreed to accept this waste through
its regular curbside yard waste collection program. Kaknes Wood Products
in Woburn composts the city's yard-waste and has also been composting the
Watertown Yacht Club's harvest for several years. The waste is first put
through a grinder which destroys the very large (1-1/2") seeds. The
city's waste transporter will be fully informed of the slight contamination
of this waste with sewage, and all harvests will dry at least overnight to
further reduce risks. Barrels will be filled to 2/3 capacity to avoid spillage
and any need for direct contact. If for any reason these composting plans
should fail, the City of Cambridge will accept the harvest as garbage to be
landfilled. Attached is a letter from the Cambridge DPW committing to accept
this waste for the first year. Extensions are expected to be obtained as
needed, and volumes should fall sharply in the last two years of this program.
Permits - An MDC permit for activity affecting MDC-owned waterways is required
from Don Guidoboni in their permitting office. I have applied for this and
have verbal support from the MDC Planning Office. Approval letters from Conservation
Commissions in the four towns affected to Mr. Guidoboni are needed.
Schedule - Beginning mid-April 2000, scouting trips will verify locations
and sizes of significant clumps. As often as seems useful, but at least monthly
beginning mid-May and continuing through October, all visible plants will
be harvested and the local water bodies will all be checked for any new plants.
This will continue for three years, hopefully with significantly less effort
required in later years. It is hoped that if surveys locate more plants in
the Alewife Brook watershed this work might be expanded off MDC land in later
years.
Studies - Note the growth characteristics and maturation dates in local
waters and compare them with those reported inland at efforts in the Connecticut
River valley to determine best times to harvest. GPS coordinates, number
of plants and weight of harvested plants will be recorded at each infestation
so efficacy can be determined in out years.
Surveys - At least once in mid-summer, all other waterbodies in the Alewife
Brook watershed will checked for water-chestnuts. This includes, but is not
limited to: Spy Pond, Menotomy Rocks Pond, Clay Pit Pond, Black's Nook, Little
Fresh Pond, and Fresh Pond. A report on the harvest, studies, and surveys
will be sent to the MDC and four conservation commissions yearly during this
three year process.
Personnel - I expect to do the bulk of this project individually, as I am
retired and able to commit to harvesting at the most propitious times. On
parts of the project, up to five additional volunteers may be used. Only
adults fully apprised of and equipped for the risks will be used.
Protection - All of this waterway is currently contaminated with sewage
which will likely not all be cleaned up even after three more years. I will
personally be wearing shoulder-length gloves when reaching into the water
to harvest plants. I currently kayak these waters and regularly get my hands
and gloves wet on the paddle, and splash a couple of pints into the boat and
on myself, and take no precautions other than a good shower afterwards. Some
volunteers may opt for a surgical mask to guard against aerosol droplets,
while others may use lab goggles to ward against splashes in the eyes.
Wetlands Protection - I see two points of concern for the wetlands: 1) avoid
impact on the shoreline and bank area when moving tools, plants, and personnel
to and from the water. There are docks at Little Pond and on the Mystic River
which allow the bank to be avoided entirely. For access without docks, such
as Blair Pond, all equipment and plants will be lifted across the shoreline
and stable areas of bank will be used for entrance and exit. 2) minimize
disturbance and resuspension of sediment. Harvesting will be from small boats
to completely avoid the effect of walking across the bottom. The stems are
said to often break off without the roots, but sediment dislodged by any roots
removed will largely fall directly back into place. The dry days chosen for
clean-water reasons will also have lower flows and little sediment transport.
The removal of these plants from the yearly biomass will reduce sediments
and oxygen depletion in future years.
Goals - The simple goal is eradication within an entire watershed, to show
it can be done and challenge others to extend the effort watershed-by-watershed.
Near term; methods, timing and tools for hand harvesting will be tried and
reported on. The recording of locations, numbers, and amounts will enable
any results to be clearly measured.
Benefits - Elimination of this invasive plant will greatly reduce sediment
and Biological Oxygen Demand from decaying plants. The removal of large mats
will improve navigation, allow light into the water column, reduce nighttime
oxygen depletion caused by plants, and stop localized trapping and buildup
of sediment which creates sandbars. Yearly reports will document locations,
numbers, and mass of plants removed, and any further waterbodies where infestations
are found. Maturation rates and ease/efficiency of harvesting on various
dates will be recorded as well as the efficacy of various implements used
on occasion. All plans and results will be posted on the internet to encourage
expansion of harvesting to other areas and groups.
Roger Frymire
22 Fairmont Avenue
Cambridge 02139-4423
617-492-0180
ramjet@alum.mit.edu