FRANKLIN – As clouds rolled over Lake Carmi and hinted at rain to come, a small pontoon rung by buoys bobbed atop the lake.
Resembling something from a science fiction novel by way of a lakeside summer camp, the small pontoon dips a sensor into Lake Carmi every hour or so, gauging everything from acidity to levels of light and everything in between.
“It creates a really holistic picture of what’s going on in the water,” the University of Vermont’s Andrew Schroth said. “Having that makes a far more comprehensive image of what’s going on in the lake.”
The sensor, one of three deployed in Vermont waters by the university to monitor water quality on behalf of the state’s Department of Environmental Conservation (DEC), provides a real time reading much of the state’s water quality testing cannot.
It also, maybe most importantly for Lake Carmi, reads the levels of oxygen floating freely within the water, a measurement that’s become key to water quality testing in Lake Carmi in light of the 80 bubblers now rumbling around the lake’s deepest waters.
“We can learn a lot more about the health of the lake with that high frequency of testing,” DEC’s Lakes and Ponds Program Manager Oliver Pierson said. “We hope that Andrew’s data will help us gauge the impact of the aeration system.”
Last year, the state turned on Lake Carmi’s aerators for the first time to at least some fanfare, igniting a series of bubblers intended to mix the waters of Lake Carmi and release oxygen near the lake’s bottom, an action that, on paper, should prevent legacy phosphorus on the lake’s bottom from being released.
Phosphorus, a vital nutrient needed for plant growth often found in fertilizers, can contribute to blooms of cyanobacteria or “blue-green algae” when washed into waterways.
While only sometimes toxic, blooms of cyanobacteria, when serious enough, can lead to beach closures and have other side-effects impacting everything from public health to the outdoor recreation some local economies rely on.
Within Lake Carmi, issues around phosphorus runoff washed into the lake and the resulting algae blooms drew widespread controversy among locals, resulting in emotional meetings with state officials and the lake’s eventual declaration as a “lake in crisis” under Vermont statute in 2018.
To hear some of the Lake Carmi campers talk about it, though, the conversation in 2020 is far different from where it was only a few years ago.
Joined Thursday by state officials monitoring Lake Carmi’s water quality, members of the local campers’ association touted newfound partnerships with state officials and local groups, and what they saw as genuine progress within Lake Carmi’s beleaguered watershed.
“We have, in my opinion, really turned the corner,” the Lake Carmi Campers’ Association’s Rob Evans said. “People can complain about how it’s not really where we want it to be, but no one can complain about the investment everyone’s made here.”
The coalition of locals and officials have managed to turn Lake Carmi into what, according to Pierson, is anecdotally one of the most heavily sampled lakes in Vermont.
While COVID-19 has led DEC to rollback its traditional volunteer-based testing for 2020, normal circumstances would see samples taken at each of Lake Carmi’s tributaries every other week, with several streams seeing multiple samples taken as a part of the biweekly schedule.
With COVID-19 thinning budgets statewide, Lake Carmi’s testing had been trimmed from its usual 19 testing sites to five, according to Pierson, with testing further complicated this month by a low flow of water through the watershed’s different streams amid a weeks-long dry spell.
The state has also recently reported significant investments made upstream from the lake, with best management practices now mandated by Vermont’s Agency of Agriculture especially cutting into the amount of phosphorus washed into the lake every year.
According to a recent progress report on Lake Carmi, DEC attributed most of the reductions in annual phosphorus runoff within the watershed to agriculture, listed under Lake Carmi’s total maximum daily load (TMDL) report as the single largest contributor of phosphorus in the watershed.
Meanwhile, Lake Carmi State Park on the lake’s southern shore has a new wastewater system resembling a pair of ponds to help eat up phosphorus once bleeding into the lake from the park’s campsites.
The basins, built only within the last few years, have helped address one of the lake’s few known “point sources” of phosphorus, which accounted for only a limited amount of the phosphorus washed into Lake Carmi every year, according to the lake’s TMDL.
Still, updating the wastewater system also represented a likely easily-addressed low-hanging fruit according to Pierson, with the wastewater treated by the ponds coming courtesy of some 1,500 visitors the state park could sometimes see in a day.
“On a summer evening, Lake Carmi can resemble a town bigger than half the communities in Vermont,” Robert Peterson, the Department of Forests, Parks and Recreation’s regional director, said during a visit to the state park.
The centerpiece of the response in the Lake Carmi watershed, however, has been the aerators now rumbling beneath the lake’s waters.
A $1 million investment, the aerators rumble the waters in Lake Carmi and disperse oxygen near the lake’s lowest layers, two processes that, according to state officials, should help disperse possible algae blooms and keep the lake’s latent phosphorus from being used by cyanobacteria.
Lake Carmi is one of the largest lakes to see the system deployed, according to DEC’s recent report on the watershed, and, according to testing within the watershed, the aerators have apparently done what DEC hoped they would in the two years the aerators have been in operation.
While those results might be worth celebrating – the state’s progress report heralds their use in stymieing the algal blooms that led Lake Carmi to be classified as “in crisis” – the systems alone haven’t cured Lake Carmi of its phosphorus woes entirely.
In 2019, the first year the aerators were operational in Lake Carmi, a large bloom of cyanobacteria came to the lake after days of hot weather mixed with a rush of phosphorus runoff courtesy of a string of storms that raged over Franklin that summer.
While sampling showed the aerators may have kept Lake Carmi’s latent phosphorus at bay, the new phosphorus washed into the lake was more than enough to fuel new blooms along the lake’s shores.
The lake has also been peppered with alerts for cyanobacteria blooms this summer as well, though nothing has appeared to approach the dramatic blooms that stung the lake in 2017, according to the local campers’ association’s leadership and the officials who met with the Messenger Thursday.
“We believe that, without the aeration system last summer and this summer, we’d have more frequent blooms,” Pierson said. “Blooms are not to the levels you would see without aeration.”
What those blooms would look like without the aerators in play could only be guessed at through modeling, and, according to Schroth, “modeling is going to be imperfect.”
How sustainable those gains are in light of a well-documented change in Vermont’s climate is also an open question, as the warmer summers and greater number of storms predicted by climatologists could lead to more phosphorus being washed into the state’s impaired waterways.
But, as the aerators continue their low rumble beneath Lake Carmi, there seems to be a breath of optimism for the only lake deemed to be amid a “crisis” under state law.
“I think people can recognize the effort being put into it,” Peter Benevento, the Lake Carmi Campers’ Association’s president, said.