By Guy Page
The State of Vermont effort to reduce cyanobacteria algae at Lake Carmi made the problem worse and will be discontinued.
Lake Carmi is a popular summer destination for Vermont families who lack the interest or finances to travel to the Atlantic coast or other popular summer destinations. Every year the state park in Franklin County is filled with families with campers and pleasure craft. It’s surrounded by farms from which come (state experts say, although not all farmers agree) large amounts of algae-inducing phosphorus runoff.
Algae blooms spiked last September, a result of conditions of “calm water, heat, and sun,” according to a summer resident quoted on News 5 last year. The result is a smelly slime that “once you’ve seen it once, you’ll never forget what it is and what it looks like,” the resident said.
The State in 2019 announced the aeration system, mandated by the Legislature’s 2018 clean waters program, The system added oxygen to the lake in hopes of reducing the ugly, toxic algae. It sort of worked, close to the surface. But on the lake bottom it merely stirred up high-phosphorus sediment. The April 16 minutes of the Carmi Coordination Team Meeting offer details:
• Low oxygen causes phosphorus to be released into lake due to internal loading
• Aeration purpose was to break up thermal stratification to allow oxygen to mix into lake
• Pre-aeration: bottom layer of lake had low oxygen levels, especially in August
• Aeration system did as expected and created less stratification
• Phosphorus levels in surface waters increased in years following aeration
The aeration was partially successful at reducing stratification. However, the system had unintended consequences of mixing bottom-water total phosphorus into surface waters earlier in season. This resulted in much higher surface water total phosphorus and stronger, more protracted cyanobacteria blooms.
Aeration has been effective in other lakes but does not seem to be good solution for Lake Carmi. The equipment will be removed this fall. A removal plan is in process.
Vermont water quality advocate James Ehlers called the outcome “entirely predictable.”
“Some of us went on record when it was first proposed that it was a waste of public money, that it was merely political gesture,” said Ehlers in response to a VDC comment this morning. “Unfortunately, we were right. Until industrial dairy is prohibited from using the watershed as its own corporate manure pit, the lake ecosystem will continue on a path to collapse and public assets will be squandered.”