Krupp: Phosphorus Overload

Feb 7, 2018

On snowy evening just before Thanksgiving, a meeting was held in Franklin, Vermont to discuss toxic pollution in Lake Carmi.

Over the summer a cyanobacteria blue-green algae bloom had kept Lake Carmi closed. The result of excessive phosphorus, most of it had originated from manure and industrial fertilizers spread by dairy farmers in the area.

Nearly 50 citizens showed up to meet with a group of Vermont Senators. Earlier, the senators had toured the Lake Carmi region, visiting confinement dairies, the waterfront, and the tributaries that serve as the passageways for the farm-derived phosphorus to make its way to the once-pristine lake.

Farm closures in Burlington, Winooski and elsewhere have led to an influx of dairies in Franklin County, where Lake Carmi’s located. Between 30 percent and 40 percent of Vermont’s cattle live in Franklin County. As a result, Franklin County is now Vermont’s top dairy producer, home to more than 36,000 cows and 48,000 people.

Phosphorus has been building up in Lake Carmi for some time. The chemical bonds to silt, and the phosphorus-laden silt settles to the bottom of the lake. Come spring, as water from the lake bottom circulates to the top, that phosphorus-laden lower layer gets exposed to sun, enabling blue-green algae to thrive.

Robert Cormier, who lives a quarter of a mile from the shore, says, “If you know what split-pea soup looks like, it looks like pea soup.” Lake Carmi now experiences cyanobacteria outbreaks almost every year, but 2017 was especially bad – complete with fish die-offs and numerous closures of camps, beaches and businesses.

The senators got an earful from local citizens on Vermont’s sacred cow – Big Dairy. Many of those testifying pointed out the obvious: If nutrient overload is the problem, no new nutrients, which leach through the waterways, should be applied until the problem is under control.

And just last week, Governor Phil Scott released a plan at the Vermont Farm Show to reduce farm-based phosphorus pollution by working with farmers to capture and commercialize this valuable mineral. But only time will tell if this idea has any practical value.

As I look out on today’s frozen landscape, I’m reminded of the many warm summer days I once spent canoeing on Lake Carmi and I wonder if I’ll ever be able to canoe on this beautiful lake again.