What is Milfoil?

Eurasian milfoil is an aquatic invasive species that can grow into thick surface mats that interfere with swimming and boating activities and crowd out native fish and plant species. It is not native to North America, likely arriving in the 1940s. Today, however, it is found in lakes and ponds across much of North America. Milfoil plants grow through a root system and also from fragments that float downstream or are attached to boats or their propellers. The fact that the plants spread so easily, coupled with a growth rate of a foot a week in the hot summer months makes this plant extremely invasive if left unchecked. Any disruption to the water, such as flooding, outboard motors, or other disruption easily causes fragmentation and the spread of the plant.


History

1998-2013. Milfoil was first found in Lake Rescue in 1998. The LRA Board at that time acted quickly to employ divers to hand pull the discovered plants and each following year divers have been employed by the association to survey the lake. From 1999 to 2003 our paid divers searched and removed about 100 milfoil plants. Lake Rescue was free of milfoil from 2004 until 2013. Tropical Storm Irene hit our region in 2011 and the massive inflow of sediment from that storm into our lake made it difficult to search for milfoil in 2012 and 2013, when the first, new milfoil plant was found by professional divers.

2014-2018. The LRA Board increased the number of days in 2014 and 2015 that divers were employed to survey and hand pull milfoil plants. In 2014, LRA began its Greeter Program, greeting boaters at the Fishing Access boat launch to check for plant material on boats. In 2015 LRA hired Shane and Cat Yoder, who have solid experience recognizing and hand extracting milfoil. Despite the efforts of the divers, a significant increase in milfoil plants was found in Lake Rescue in 2015 (see comparison maps); divers found no Eurasian Milfoil in Lake Pauline. In 2016, LRA commissioned the Yoders to increase their visits to twice a week, which seemed effective in stopping the expansion of milfoil. We also marked off the worst area in Round Pond to keep boats out, and obtained a ‘suction harvesting’ permit, in case hand-pulling became insufficient. In 2017, our divers visited our lakes 31 times, and in 2018, 27 times. We also increased the number of days for the Greeter Program. 2018 saw a marked increase in milfoil harvesting, from about 1,000 milfoil plants pulled (or 136 gallons) in 2017 versus about 2,058 plants (or 361 gallons) in 2018. While in 2017 the divers reported that milfoil had spread to more locations, there were no dense patches nor multi-stalked second-year plants found. Most of the plants found were young and growing sparsely, which was hopeful news. However, this changed in 2018, where dense patches had developed. We agreed to increase diver days in 2019 and applied for a state permit for bottom barriers.

2019-2020. In 2019, diver days were increased from 2 to 3 days a week, and 24 benthic bottom barriers were purchased. These synthetic 10' x 50' sheets were placed on the lake bottom in the northwestern part of Lake Rescue and were effective in killing the vegetation underneath. They were moved mid-summer to other densely infested areas. While we were encouraged that the 2019 harvest was less than in 2018 (275 gallons versus 361 in 2018), growth was discovered in new areas of the Lake Rescue, and also, for the first time, in Lake Pauline. We determined to purchase more bottom barriers and continue more aggressive hand-harvesting. However, in 2020, we saw an unprecedented explosion of milfoil that necessitated further measures. LRA purchased 24 additional bottom barriers, for a total of 48, and extended the hand harvesting to Lake Pauline. We also changed our policy to train and allow homeowners to do their own harvesting around their lake fronts. It was clear by late summer the milfoil had gotten out of control, and in early October, the LRA hired Chris Sheldon, a diver assisted suction harvesting (DASH) contractor, to suction harvest in Round Pond for a week, which garnered a harvest of about 5,000 gallons of milfoil. We are grateful to the many LRA volunteers who arrived by kayak to collect the loose milfoil fragments produced by the harvesting.


Current Status

Because of the extreme milfoil growth that developed in 2020, in October the LRA board agreed to purchase our own diver-assisted suction harvester (DASH) boat. A pre-owned pontoon boat was purchased and will be retrofitted by our divers as a DASH-equipped boat, ready to employ on July 1, 2021. (By VT state law, we must wait until July 1 when the primary fish spawning season is over.) This method is exponentially more effective than hand harvesting, and we estimate will pay for itself in about 2 years. Our divers will place the 48 bottom barriers, engage in DASH harvesting 3 days a week, and/or will perform hand harvesting in where DASH is not feasible, such as in Lake Pauline and in small coves. We are hopeful that within two or three years we will have milfoil under control, though probably not eradicated, and continued vigilance will be required long into the future.


Cost

The chart below outlines the increase in milfoil mitigation costs since 2015. We have gone from $8,100 total cost in 2015 to $64,000 in 2020. These costs have been funded through modest state grants and member donations to LRA’s Rescue Our Lakes fund. Because of the generosity of our members, until 2020 we have been able to manage costs. However, we are now at a point, similar to the situation many other Vermont lakes face, some of whom spend over $200,000 a year battling milfoil, of embarking on a major fundraising campaign to begin late 2020 and into the next couple of years. We envision our costs decreasing over time with aggressive DASH harvesting, but we aren't there yet.


Year

Plants Harvested (approx.)

   Methods

Total Cost

VT State Grants 

Net cost to LRA

2015 (400+/- plants)

70 gallons

 13.5 diver days

Boat greeters

$8,100 ($2,360) $5,640
2016 (600+/- plants)

95 gallons

19.5 diver days

Boat greeters

$12,750 ($7,580) $5,170
2017 (1,000 +/- plants)

150 gallons

31 diver days

Boat greeters

$15,130 ($6,100) $9,030
2018 361 gallons 27 diver days

Boat greeters

$14,725 ($7,600) $7,125
2019 275 gallons 29 diver days

Boat greeters

24 bottom barriers

$20,152 ($3,700) $16,452

2020

6,700 gallons 42 diver days

Boat greeters

48 bottom barriers

Hired DASH work

Resident volunteer hand harvesting

$42,365 ($7,500) $34,865
2021 (estimates) tbd 40 diver days

Boat greeters

48 bottom barriers

DASH boat purchase & costs

Resident volunteer hand harvesting

$51,000 ($3,000) $48,000

Identifying and Reporting Milfoil

Milfoil is not difficult to identify. It typically grows in shallow (less than 20 feet) water and the tops of the plant, both stems and leaves are often red.

It has a stem with whorls of four featherlike leaves. Each leaf is finely divided into 12-21 paired leaflets. The plants grow up from the bottom up to the surface and can have many side stems. If you see such a plant, email us right away with the location at lakerescueassn@gmail.com., mark it with some kind of temporary buoy, and our divers will come and investigate when they are at the lake. Alternately, with training, homeowners can carefully pull the plants in shallow areas surrounding their waterfront. Click HERE for instructions.

It is illegal in Vermont to transport Eurasian watermilfoil, along with zebra mussels and water chestnuts, on boats and boating equipment. Any person found transporting any of these species to or from a Vermont lake or pond will be in violation of this law. CHECK YOUR BOATS when entering or leaving the lakes for milfoil fragments. Penalties for violations could include fines, imprisonment, or both (pursuant to 10 V.S.A. §1266).

Eurasian Milfoil Factsheet preview.pdf

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