Porter: Why Vermont waterways turn pea-soup green with algae

Editor’s note: This op-ed is by Louis Porter, the Lake Champlain lakekeeper for the Conservation Law Foundation and former chief of the Vermont Press Bureau.

Last Friday, I saw what a severe blue-green algae outbreak can be like at its worst.

As we motored across the Missisquoi Bay towards the eastern shore, the bow of the boat parted a layer of scum, striated with foam from light brown to white. In the rare spots where the water was roiled enough to see below the surface, there was only darkness.

The pea-soup algae bloom farther out was replaced with what looked like forest-green latex paint under a dense coating that resembled the surface of a salt flat desert from above. Rocks along the shore (a few dozen yards from a line of pretty but modest houses) were coated with residue of the same nasty stuff.

And then there was the smell. Having grown up on a small farm and worked in fish processing plants, I am no stranger to the smells animals make, living and dead. This was something different. It was hard to believe a living organism could produce such a chemical stench.
But in some ways what was most shocking about the Missisquoi Bay bloom was not the smell, or what it looked like, but what we saw on the way to it.

The nearby Missisquoi National Wildlife Refuge, where the river joins Lake Champlain, is one of the most incredibly beautiful spots in Vermont. This confluence is reminiscent of the rich estuaries in the Chesapeake Bay, and great blue herons seem as common as seagulls along the river mouth. Their angular forms can be seen a half-dozen at a time, and their nests, vacant for the year now, stand out against the sky atop the highest trees along the shoreline. Kingfishers flash just over the surface of the water, while ospreys are a not-unusual site at tree-top height.

Missisquoi Bay itself is also wonderful. Large enough for boating, but small and protected enough for swimming, it is a nearly perfect natural harbor. But on that recent Friday, most boats were pulled up on shore, although a few fishing boats worked the parts of the bay less affected by the giant bloom. Kayakers, sailors, swimmers and water skiers were conspicuously absent despite the warm sunny weather and the arrival of the weekend. Who could blame them – such blooms make those uses of the water unappealing at best and potentially dangerous at worst.

A high alert, as defined by the Vermont Department of Health, is when a dense bloom of blue-green, also known as cyanobacteria, is dense enough to produce toxins “above levels of concern.” In those areas, “the water is not safe for recreational use.” Animals sicken if they drink the water. Children, who are particularly susceptible, must be watched carefully to make sure they don’t go in the water.

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Blue-green algae is natural and common, not only in Lake Champlain but in many other places as well. But large blooms that produce potentially harmful toxins in large volumes are exceptional. They are our fault and responsibility.

Manure runoff, polluted water from developed land and wastewater plants all add nutrients to Lake Champlain. Combined with the wrong weather (made worse by climate change) such contamination can only be expected to get worse. The usual advice to simply avoid such scums, while correct, ignores the reality that such blooms will become more common and more widespread if we don’t change how much phosphorous waste we add to Lake Champlain.

As such blooms become commonplace outside of Missisquoi and St. Albans Bay we may see local effects, like Vermont drinking water systems forced to advise residents not to use the water, as well as economic effects, like declining tourism and fishing revenue, that will harm us all.

Blooms like those last week on Missisquoi Bay should not be happening at all, and they certainly should not be happening in Vermont. If we don’t do something about them, we may find ourselves like the child we saw on the beach near the worst of the blue-green, standing on the shore in our swimming trunks with nowhere to go.


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