Eurasian Watermilfoil – Silent Deadly Invader
Over the past 10 years Eurasian Watermilfoil (EWM) has gained ground in Farlain Lake. The invasive aquatic plant now dominates one third of the lake’s water surface and two thirds of the lake’s shoreline. The total acreage has increased from 2 acres in 2018 to 100 acres today.
Dense floating mats of EWM have impeded recreational activities such as swimming, fishing, water skiing, and boating. The invasive plant has drastically altered the lake’s ecology. Popular game fish have disappeared from the lake along with a number of aquatic animals and waterfowl. In sheltered areas, stagnant mats of vegetation are breeding areas for mosquitoes. In addition to the odour of decaying EWM biomass the lake’s level is becoming shallower as the dense decaying vegetation adds to the lake’s sediment.
Due to the decline of the lake’s use and aesthetics, property values have decreased 16% on average.
Any control and remedial work undertaken to manage EWM in the future will involve significant financial and time expenditures. The only viable control method to manage EWM will be deep dredging of the lake.
The above notice is a projection (see news release date) of a realistic possible situation in Farlain Lake if Eurasian watermilfoil management efforts are not continued. Unlike the 1938 War of the Worlds radio broadcast by Orson Welles, the scenario of fighting an alien invader in Farlain Lake is real.
Despite FLCA’s efforts to manage EWM since 2014 the invasive aquatic plant has spread to other areas of the lake. In addition to the pioneer colony, new infestation sites have been observed in four different locations on the west side of the lake. Some lake residents have attributed the spread to FLCA’s control efforts. Others have stated that Eurasian watermilfoil has always been in the lake and the aquatic plant is not a problem.
Fact: Prior to its discovery in 2012 during a FLCA aquatic plant study of the lake, the invasive plant was not observed in the lake by Ontario government organizations studying the water quality or the fisheries of the lake.
Fact: The FLCA has taken extra steps to prevent the creation and dispersal plant fragments during its control efforts. Floating containment curtains were positioned around work sites to capture incidental plant fragments. EWM will grow from plant fragments created from physical breakage by boaters, anglers, and other disturbances (e.g. forceful wave action, aquatic animals, fish, waterfowl, etc.) during the summer months. In late fall during the end of its growth period EWM becomes brittle and naturally break apart. Plant fragments are the primary means of EWM reproduction; they float on the surface and are dispersed by wind and wave actions to other areas where they sink and colonize into new plants. In optimum water temperatures (15°C - 35°C) EWM plants can grow 30 cm per week.
Fact: The natural ability of EWM to spread without management efforts is well documented. In a research paper Arresting the Spread of Eurasian Watermilfoil in the Great Lakes by the Michigan Tech Research Institute reference is made to a study of a small (250 sq. ft.) EWM infestation that was recorded in 2006 in the Les Cheneaux islands of Northern Lake Huron. The small unmanaged patch later grew to a dense mat of over 400 acres by the end of 2012.
How Bad Can It Get?
No two water bodies are alike. Aquatic plants grow in the littoral zone; this is the area where sunlight reaches the bottom and plants grow. Beyond the littoral zone plants don’t grow due to deeper depth. Eurasian watermilfoil typically grows in ten feet of water and can grow to 30 feet in length; the upper canopy of vegetation creates the floating mats.
Fact: With the exception of two isolated areas of Farlain Lake that are 17 feet deep the overall lake is primarily a littoral zone. EWM could eventually fill in this shoreline zone particularly in areas where the lake bottom sediment is deep muck.
What Has Been Done?
Hand harvesting EWM plants by commercial divers in the pioneer colony began in 2014. In 2016 EWM hand harvesting was not undertaken; an experimental pilot project using jute benthic mats (a bottom barrier made of burlap covering the plants) was implemented.
In 2017 hand harvesting using a DASH (diver assisted suction harvesting) system was used; DASH simplifies and expedites the transport of hand harvested material to the surface for collection and disposal.
The FLCA built its own prototype DASH system at a cost of $12,000; although the DASH system has been used in the USA for the past decade this is the first time the system has been used in Ontario.
The FLCA also purchased its own 400’ floating containment curtain at a cost of $8500. The floating containment curtain is positioned around the work site to restrict the dispersal of any plant fragments created by the control efforts. The use of a floating containment curtain to confine a control project is not normally done by groups combatting invasive aquatic plants; the FLCA has made the use of a containment curtain a key component of its control efforts. As underwater hand harvesting work must be performed by certified divers a dive company (Lower Lakes Marine) and its dive boat was contracted for two days in 2017 at a cost of $8900. Scuba divers also hand harvested EWM plants from a small infestation at the very north end of the lake. Dedicated FLCA volunteers supported the hand harvesting work.
Volunteer divers from outside the lake community have mapped, assessed, and video-taped the pioneer EWM colony pre and post harvesting in 2017. Lake community volunteers monitor the lake for new EWM infestations.
As there is no Government funding available to support FLCA’s EWM control efforts, volunteers undertook a multi-faceted fundraising initiative in 2017 as part of a three year fundraising goal of $80,000. The fundraising initiative involved a direct mail campaign targeting lake community property owners, the sale of a FLCA designed/produced 2018 calendar, obtaining advertising revenue for the calendar, crowd funding, and other initiatives. A key fundraising project was the outdoor Aquatic Weedfest which involved a BBQ, live music, silent auction, JunkTique yard sale, children’s creative zone, and educational displays.
Fact: $42,923.68 (54%) of the three year $80,000 fundraising goal was raised in 2017. Of this total revenue $34,870 (81%) was raised through the direct mail campaign. Three shoreline property owners donated a total of $15,000 (43%) of the total amount of direct mail campaign donations.
Fact: Of the estimated 195 shoreline properties in the lake community only 62 (32%) property owners made a donation. Of the estimated 172 inland properties only 11 (6%) made a donation.
Fact: Of the estimated 975 permanent and seasonal lake community residents, a core group of 13 (1%) lake community volunteers undertake research, develop communication material, organize and implement fundraising initiatives, and oversee EWM control efforts. Of the total number (975) of lake community residents 3% (31 volunteers) are actively involved in EWM control work and fundraising.
Results to Date
Since implementing a EWM control program in 2014 the FLCA has developed a sound scientific understanding of the invasive plant and acceptable control methods. We have learned from our previous control efforts and have refined those methods. We have developed an efficient method
(DASH) system of transporting hand harvested plant material to the surface.
In 2017 we removed approximately 5200 lbs. of EWM plant material from the lake over a two day period. A preliminary post harvesting assessment of the pioneer colony shows areas where EWM plants have been removed leaving open areas on the lake bottom. Other areas of the dense EWM vegetation that were harvested show a regrowth of invasive aquatic plant. Areas of the pioneer colony that were covered in 2016 with jute benthic mat show the absence of EWM plants where the burlap bottom barrier was positioned properly over the infestation. Approximately 75% of the EWM plants in the small scattered infestation at the north end of the lake have been removed.
Fundraising efforts have generated nearly $43,000 in year one (2017) of the three year fundraising campaign. However expenses (e.g. contracted commercial divers, DASH system development, containment curtain, etc.) totaled $30,000 in 2017 leaving a balance of $13,000 to undertake EWM control efforts in 2018.
Fact: EWM is considered one of the most widely distributed aquatic invasive species with records of EWM confirmed in 47 continental USA states as well as the provinces of British Columbia, Ontario, and Quebec. Various organizations have been combatting EWM for years. For example, Lake George in New York State’s Adirondack Park has been managing EWM for 32 years. The Okanagan Basin Water Board in British Columbia has been combatting EWM for the past 40 years. Control budgets vary depending on the severity of the problem and the size of the water body. For example, the Christina Lake, British Columbia, EWM control program is $213,000 annually. To manage EWM and improve the lake’s water quality in Puslinch Lake Ontario, through dredging the annual operating cost is approximately $150,000.
Priorities for Control
The FLCA EWM Steering committee is currently developing a management strategy for 2018. Despite another difficult year to control the growth of EWM in Farlain Lake the volunteer committee has decided that it is wiser to continue the EWM management efforts rather than do nothing. Effective EWM control will require a sustained and long-term commitment of education, research, management, and monitoring.
The control methods of hand harvesting using the DASH system augmented by strategically placed jute benthic mats will be utilized. The highest priority areas for control are the heavily infested areas that are sources for spreading plant fragments created by recreational and natural activity.
While the donor appeal campaign is ongoing and other fundraising initiatives will be undertaken in 2018, fundraising will be focused on grant applications to seek funding for the 2019 operational year.
Fact: According to Dr. John Madsen, University of California-Davis, there is “no one group dedicated to research on Eurasian Watermilfoil. There isn’t funding to support research on one species like this. Funding is intermittent and goes to different species, depending on the priority.”
As there are no recent research studies in EWM in the USA or Canada on effective control methods it take several more years before the elusive ‘silver bullet’ to control EWM will be discovered, trialed, and successfully implemented. The FLCA will need to rely on proven safe control methods to manage the growth of EWM within the lake.
We are dealing with a critical issue affecting the long term health of Farlain Lake’s ecosystem, lake usage, and property values.
There are five key challenges to managing EWM in Farlain Lake...
1. Sustained Funding
Due to the lack of external funding necessary funding must be provided by those who will benefit from the EWM control effort……the lake community. However, nearly 70% of the shoreline property owners and 94% of the inland property owners did not make a donation in 2017. There may be extenuating circumstances which prevent some property owners contributing money. However the majority of property owners….particularly shoreline property owners who have the most to lose if EWM dominates the lake…have disposable income that could support the ongoing EWM control efforts. These property owners are not investing in the future of the lake.
2. Volunteer Sustainability
Only a small core group of volunteers undertake the majority of the EWM control program work throughout the year. This group of dedicated volunteers represents 1% of the lake community’s population. Furthermore 97% of the lake community does not volunteer their time for EWM control project work or for fundraising efforts. Those who choose not to donate their time, skills, and experience may cite various reasons (e.g. personal commitments, limited free time, health issues, etc.) for not supporting the EWM control effort. Yet those who volunteer also have personal and family commitments, limited free time whether they are fully employed, partially employed, or retired. There are community residents who have health and mobility issues but are able to volunteer where they can. The reality of the volunteer situation is that volunteer fatigue will become a reality as the same volunteers are called upon time and time again to undertake the necessary fundraising and EWM control work. Eventually EWM control efforts and fundraising will need to be contracted out or not done at all.
3. EWM Control Options
Our options of proven control methods are limited. There are no viable biological control methods. Unlike the United States where the primary control method is the application of various types of aquatic herbicides, the only herbicide approved by Health Canada to manage invasive aquatic plants is a contact herbicide (brand name Reward) that only slows the plant's growth rather than kill the plant. Mechanical harvesting and chemical herbicides only provide short-term control and have negative impacts on native vegetation.
4. Natural Circumstances
It is impossible to accurately predict a five year strategic management program as control efforts will be affected by uncontrolled and unpredictable natural circumstances (e.g. weather patterns, water level fluctuations, variations in water temperature, etc.).
With the exception of new property owners, there is no excuse….other than apathy… for lake community property owners to not comprehend the threat EWM poses to the lake’s values we all share. The FLCA has erected an information sign at the boat launch area on Andrew Drive, it has created publications and displays, and the Association has distributed information door-to-door around the lake community and has mailed information directly to property owners’ home addresses. The FLCA has written articles for the Tiny Cottager newsletter which is mailed to each property owner’s home address. FLCA members receive ongoing EWM related information through the FLCA website, newsletters, and E-blasts. Each FLCA Annual General Meeting features an update on the EWM issue. Yet the majority of lake community residents are oblivious to the EWM threat and the fact that their recreational activities (e.g. boating, angling, etc.) contribute to the spread of EWM within the lake. One day in the not so distant future when dense EWM vegetation appears on these property owners’ shorelines they will be first to complain that previous control efforts were in inadequate.