Thanks to Rick Delaney for sharing this article with the MLA
State Of The Lake: Inside Lake Leelanau's Productive
Summer Battle Against Eurasian Watermilfoil
By Craig Manning | Aug. 30, 2023
Two steps forward, one step back: That old adage might just be the perfect way to
encapsulate where things stand in the war the Lake Leelanau Lake Association (LLLA) has
been waging against Eurasian watermilfoil (EWM), the extremely destructive invasive
plant species first found in Lake Leelanau waters in 2019.
According to Annalise Povolo, who serves as director of administration and programs for
the LLLA, the organization has had an immensely productive summer in combatting the
growth and spread of EWM. But not everything is rosy – especially given the fact that
recent climate change factors seem to be driving faster proliferation of EWM in Lake
Leelanau and the waters of other infected lakes.
“We've heard from other lakes that their EWM also had a really good year,” Povolo tells
The Ticker, noting that this past winter’s warm and mild weather proved extremely
favorable for the growth of the invasive plant. In a typical winter, inland lakes like Lake
Leelanau end up with cold waters and considerable ice and snow cover, which in turn
starves invasive plants like EWM for light and forces them to go relatively dormant.
Without a typical level of ice and snow cover, though, EWM “was able to grow more than
normal throughout the winter,” Povolo says.
All that growth meant the LLLA was fighting a different war at the start of the 2023 season
than it was last fall. At the conclusion of the 2022 field season, LLLA had hired a company
called Zero Gravity Aerial to perform a full drone survey of Lake Leelanau. “This survey
provided us with the precise locations of the EWM in the lake, from individual patches to
large infestations,” Povolo wrote in a recent newsletter. “Using this information, we set
out at the beginning of the [2023] season with a ‘plan of attack’ for our fight against EWM
with an artillery of tools.”
But that plan wasn’t calibrated to the wintertime growth, and a second survey by Zero
Gravity Aerial this past spring showed that the chessboard had shifted significantly during
the offseason. There was more EWM in more places, making it clear to Povolo and her
team that they were going to need to “kick it into high gear” and have an immensely
productive summer to beat back the creeping presence of this invasive species.
Fighting EWM has become the top summer priority for EWM this decade. The invasive
species was first identified in the south lake in 2019, and efforts at managing infested
areas began in earnest during the spring/summer season in 2020. Those management
efforts have grown each summer since, requiring more resources, more hands on deck,
and more investment from LLLA and its supporters.
Per Povolo, though, that vigilance is essential to save Lake Leelanau from the damage
that EWM could cause if allowed to run rampant. In her recent newsletter, Povolo wrote
that the invasive plant “can grow up to the lake’s surface, choking out native plants and
growing dense mats – making some highly infested areas impossible to swim in and drive
boats through.”
The good news is that, while the LLLA may have lost a battle to EWM over the winter, the
organization seems to be winning the war. Povolo reports that “two larger, previously
treated sites” of EWM in Lake Leelanau are now completely free of the invasive plant,
proving that it can be eliminated with the right tactics. She’s hopeful that this summer’s
record-breaking efforts from the LLLA team and its many volunteers will show even more
substantial gains come next season – even if the winter forces the organization to settle
once more for a “two steps forward, one step back” outcome.
LLLA has been able to eliminate EWM by covering up infestations with large
biodegradable burlap barriers. Those barriers – essentially big, sprawling burlap blankets
– cover over the plant and starve it of sunlight, disrupting the photosynthesis process for
long enough that the plants die off. As Povolo explained to the Leelanau Ticker last year
(https://www.leelanauticker.com/news/how-it-startedhow-its-going-an-invasive-eurasianwatermilfoil-
update-from-lake-leelanau/), this approach works because EWM has not yet
established a seed bank at the bottom of Lake Leelanau. In lakes with out-of-control EWM
infestations, the plant has been allowed grow to the surface, where it flowers and
produces seeds. Those seeds then sink to the bottom, establishing the kind of seed bank
that can perpetuate EWM even if the plants themselves are killed off. In Lake Leelanau,
native plants have seed banks but EWM doesn’t, which means that eliminating EWM
infestations opens up those areas for native plants to grow back.
In 2022, Povolo says LLLA was able to set 2.2 acres of burlap over EWM infestations in
Lake Leelanau – nearly 96,000 square feet. Already this year, the organization is up to
over four acres of coverage, and Povolo anticipates that, “by the end of this season, we
could almost double what we did last year.” Another drone survey this fall will offer some
clarity on how much progress LLLA has made.
When asked how LLLA was able to have such a record-breaking summer of anti-EWM
efforts, Povolo points to numerous factors. For one thing, favorable weather allowed
crews to notch more days out on the lake. For another, a veritable army of volunteers
came out to help with efforts this summer – including, on one day in July, more than 20
community members who assisted in laying down “1,200 feet of burlap, all in one line.”
A robust partnership with the Grand Traverse Band of Ottawa and Chippewa Indians has
been extremely valuable as well, Povolo adds, as has the financial support from the Keller
family, the local philanthropists who are funding LLLA’s “aquatic invasive species
remediation control and prevention efforts” on a three-year basis, from 2022 to 2024.
That financial support meant LLLA this summer was “better equipped than we had ever
been in previous years,” per Povolo, with three boats dedicated to EWM remediation, a
full-time seasonal technician “to drive our boats and prepare materials,” more biologists
on staff to lead the efforts, and more SCUBA divers “than we had ever employed” to take
care of actually laying the burlap over the EWM infestations.
Povolo is hopeful that the LLLA will be able to hire even more divers to expand its EWM
remediation efforts in future years – a goal that could be helped by the creation of a
brand-new charitable foundation. That foundation, called Friends of Lake Leelanau, will
eventually take the baton from the Keller family to fund LLLA’s fight against invasive
species. Povolo tells the Leelanau Ticker that Friends of Lake Leelanau is currently setting
up an endowment with the goal “to have it up and running by January 1 of 2025.”
“At that point, LLLA will apply for grants from Friends of Lake Leelanau, who would then
award us the grants from the money that has been raised in that endowment,” Povolo
explains.
