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It’s been almost five years since Vermont officials declared Lake Carmi to be the state’s first “lake in crisis,” a designation that spurred a plan for cleaning up the troubled body of water in rural Franklin County and stipulated how to pay for the work. 

At the time, efforts to clean up the state’s fourth-largest lake, and its watershed, were already underway. In 2019, officials launched perhaps their most ambitious project there: a $1 million aeration system designed to pump oxygen into the water, curbing the release of phosphorus that feeds blooms of noxious cyanobacteria, known more commonly as blue-green algae.

Three years later, it has yet to function properly for an entire summer — the most critical time for reducing phosphorus. Officials say there were problems from the beginning, and malfunctions may have made blooms on the lake in recent summers worse. 

People who recreate in and around the lake are also concerned that 2022 could be the final year a University of Vermont Extension monitoring platform operates on the water, providing them near real-time data on lake conditions.

State officials say they’re confident they have worked out all the kinks in the aeration system, which, when it runs as intended — and runs consistently — has been effective at reducing the release of phosphorus. And in the watershed around the lake, officials say farmers have made significant progress in reducing the amount of phosphorus entering the water. 

Still, cyanobacteria blooms have continued to appear on the lake, and advocates say the work is far from finished. The pressure is on — locals believe this will be Lake Carmi’s busiest summer since the pandemic started, due in part to the return of tourists from Canada, which is less than two miles north. 

“There is significant work that’s been done,” said Rob Evans, president of the Franklin Watershed Committee. “But we haven’t seen that improvement that we would like.” 

Lake Carmi State Park boasts the largest campground in Vermont. In the summer, the lake is a popular destination for walleye fishing and other outdoor recreation.

But the 1,375-acre body of water — along with nearby Lake Champlain — has been plagued for decades by phosphorus pollution, largely caused by agricultural runoff. It has been classified as “impaired” under state water quality standards.

In 2017, cyanobacteria blooms at the lake were bad enough to close its beaches for weeks. Locals “raised holy hell,” as former Rep. David Deen, D-Putney, put it at the time. Their advocacy led to legislation a year later that required the state Agency of Natural Resources to come up with a “crisis response plan” for the lake.

A draft update to that plan, published two months ago, estimated that by the end of 2020, Vermont was just more than 40% of the way toward meeting its target for the maximum amount of phosphorus entering the lake each day. 

Oliver Pierson, who manages the Vermont Department of Environmental Conservation's Lakes and Ponds Program, noted the state’s estimate is based on modeling because it has no way to definitively measure the flow of external phosphorus into the lake.

Despite this progress, Lake Carmi still faces persistent challenges from internal phosphorus that has built up in the lake sediment for decades. According to Pierson, this “legacy” contamination could take decades to address. 

The state is aiming to keep average summertime phosphorus concentrations in Lake Carmi at or below 22 parts per billion. That figure is based on data from years when local residents expressed satisfaction with lake conditions.

Data from the lake shows an overall improvement in water clarity in recent years, according to the updated crisis response plan. Even so, recent summertime averages continue to range between 30 and 40 ppb.

Pierson said officials are considering whether that 22 ppb target, established in 2008, is still a realistic goal. For now, he said, “that's the target we have on the books. And that's what we're working towards.”

Lake Carmi’s aeration system works by sending compressed air through a tube to a “manifold,” which shoots air into pipes spread out at the bottom of the lake. The pipes feed into ceramic diffusers with holes that send a column of air into the lake, continuously mixing the water.

When there’s oxygen present, the phosphorus in the sediment remains immobile and doesn’t get released into the water, where it could feed algae growth, according to Mindy Morales-Williams, an assistant professor in UVM’s Rubenstein School of Environment and Natural Resources.

Pierson said that during the past three summers, the aeration system has been taken offline multiple times — sometimes for the better part of a week.

In 2019, it was shut down temporarily because the compressors that pump air into the water overheated, according to Pierson. Officials had to take steps to shade them from the strong summer sun. 

In 2020, the system was taken offline multiple times due to electrical issues. 

Upgrades were again needed in 2021 as a spate of dry weather in northern Vermont led to dry soil conditions, which hindered the system’s in-ground cooling system. It was replaced with a different cooling system.

According to a 2021 UVM report on water quality in Lake Carmi — based partly on data collected by the monitoring platform — the 73 weeks between June 23, 2020, and Oct. 26, 2021 were the longest drought period on record in Vermont this century. Drought conditions can spur the release of more internal phosphorus.

The report, co-authored by Morales-Williams, found that when the aeration system works as planned, it makes the water in Lake Carmi less prone to stratification and likely limits some internal phosphorus loading from the lake sediments. 

But malfunctions in the system have made it impossible to do a comprehensive assessment of the system’s capacity to achieve its water quality goals, the report says. 

Moreover, it concludes that aeration has not mitigated cyanobacteria blooms on Lake Carmi in the system’s three years of operation, and in fact, blooms increased in 2020 and 2021 relative to previous years. 

The state’s updated plan made note of “an intense period of near-shore blooms” from August to October 2021, concentrated in the northern half of the lake.

One issue with shutting down the system during the summer, Pierson said, is that when the lake stratifies, the layers closer to the bottom are cooler, and so have less oxygen. This ultimately encourages the release of internal phosphorus. 

But turning on the aerator when the lake is stratified may just mix that phosphorus-rich water throughout the rest of the lake, he said, making conditions worse.

Morales-Williams said officials are planning to study further why blooms increased over the past two years, though it’s likely due to multiple factors including malfunctions in the aeration system and changes in the weather as a result of climate change.

“If the ‘shutdown and turn-on’ happens frequently enough,” she said, “that kind of disturbance keeps biomass very high and very stable throughout the whole season, which is what we saw in 2021.”

She also noted that last year’s conditions were consistent with a pattern, observed over decades of historical data on Lake Carmi, in which outsize cyanobacteria blooms occur once every decade or so. Scientists don’t have a good explanation for why that happens, she said.

Pierson said he hopes the upgrades made since 2019 will allow the aerator to operate normally this year, in what will be its fourth summer. 

“Knock on wood,” he said, “we can monitor its impact on lake water chemistry all summer long. And the icing on the cake would be that it actually works to suppress internal loading.” 

Dave Bennion, the selectboard chair in Franklin — where Lake Carmi is located — agreed with Pierson’s assessment of the aerator system: “We’re expecting a very good result from it this year,” he said.

Evans, of the watershed committee, said an important resource for those working to clean up Lake Carmi has been water quality data that’s been collected and published online by the University of Vermont Extension since 2020. 

The data is collected from a monitoring platform placed in the lake and is updated throughout the day, effectively in real time, according to Pierson. 

But, Pierson said, there is currently no state funding available to continue collecting that data beyond this year. The updated crisis response plan states that the Department of Environmental Conservation will collect this data for “one final season” in 2022. 

“That doesn't mean that we won't find funding to do that later this year,” Pierson said. “But I don't have that funding today.” 

Even if this high-frequency data is no longer collected, Pierson said that department staff will continue to test water samples every week during the summer. And, volunteer sampling of lake conditions between Memorial Day and Labor Day will continue as well, he said. 

The main goal of the UVM Extension data, he added, has been to track the progress of the aeration system.

Evans, who also is vice president of the Lake Carmi Camper’s Association, said he and other campers are grateful for the resources the state and other organizations have committed to Lake Carmi in recent years. 

But he made the case that in order to make informed decisions about which cleanup measures are actually working, the state should make available as much data as possible about the lake’s condition. 

“I don't think that now is the time to be turning off that sampling,” Evans said. “We need to keep our foot on the gas to make sure that sampling continues to take place.”

Morales-Williams, the assistant professor, agreed that the monitoring platform’s data is a valuable resource, and she “would really love” to continue having access to it. 

With the platform, “we know what's happening from minute to minute, and that's really important to being able to calculate rates and trends,” she said.

In April, Evans testified before the Vermont House Natural Resources, Fish and Wildlife Committee, urging legislators to allocate more funding for projects at or near the lake, including the data collected and shared by UVM Extension. 

UVM’s data monitoring this summer is funded with about $50,000 from the Department of Environmental Conservation. 

In an interview, Evans also pointed to how UVM Extension’s data is supplemented by volunteer sampling. He feels the state could bolster its progress toward its phosphorus reduction targets by making more staff available, and perhaps setting up a dedicated point person for Lake Carmi.

“We just don't have the boots on the ground to get the work done that needs to get done around the lake,” Evans said. “And I'm fearful of continuing not to make the solid improvements that we need moving forward.” 

The state’s 2022 draft crisis response plan includes dozens of projects across multiple sectors — including agriculture, groundwater, natural resources and roads — that officials say will help improve water quality in Lake Carmi.

For one, Pierson said the state is set to make improvements to a number of roads and driveways around the lake that may be contributing harmful runoff into the water.

According to the plan, farmers operating in the Lake Carmi watershed have “made significant strides” in the past decade to implement practices that reduce the amount of phosphorus leaving their fields. Those efforts include installing vegetative buffers on ditches and surface waters, rotating crops and minimizing the frequency and intensity of tillage, among others.

The state also has provided funding for an injector that incorporates manure directly into the ground, rather than spreading it on top. Pierson said this technology can help reduce the amount of phosphorus running off the soil and into the water.

Heather Darby, an agronomy specialist at UVM Extension who works with farmers in the Lake Carmi watershed, said she’s seen the work to limit phosphorus loading firsthand.

Darby said she and her team have determined that the amount of phosphorus leaving farms in the watershed over the past several years is roughly equal to the amount that is entering farms through agricultural sources, such as fertilizer and animal feed. 

That wasn’t necessarily the case a decade-plus ago, she said. Some of the phosphorus leaving farms will end up in the lake, but Darby said that every local farmer she works with is cognizant of the impact their practices have on the watershed. 

“Anybody who's on the landscape is contributing, right?” she said. “But the level of their contribution is, definitely, hugely reduced from what it was.” 

In 2008, the state estimated that 85% of the external phosphorus loading into Lake Carmi was from agriculture, according to Pierson. He said that figure has not been updated since, though it’s safe to say a majority of external phosphorus still comes from that sector.

Pierson said implementing the projects outlined in the state plan and getting the aerator system fully operational are key to success at Lake Carmi.

“If we can get those two things done, then we’re set to make real progress,” he said.

In the past 14 years Evans has lived at Lake Carmi, he told lawmakers, “not a summer has gone by that we did not experience algae blooms.”

The impact of these blooms, he said, “have led to financial, health and property value concerns that continue to raise the alarm for all of us.”

Pete Benevento, president of the campers’ association, said he hopes support for the lake cleanup will continue both from the Legislature and from the local community.

“We're making strides that I thought, years ago, was not possible,” Benevento said. He noted the relationships among all the parties involved in the lake cleanup have improved dramatically over the past five years. 

“Our efforts are to end these algae blooms,” Benevento said. “That's our endgame.”

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Shaun Robinson is a Report for America corps member with a special focus on issues of importance to Franklin and Grand Isle counties. He is a journalism graduate of Boston University, with a minor in political science. His work has appeared in the Boston Globe, the Patriot Ledger of Quincy and the Cape Cod Times.

View all stories by Shaun Robinson

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