The algal bloom last month in Lake George, the first of its kind, is one of two things: A sign of things to come. Or not.

While Lake George remains a relatively pristine lake, especially for its size, it has slowly deteriorated over time thanks to shoreline development and runoff from nearby roads. It’s still got a hot home market around it and is a draw for bustling tourists from downstate and out of state.

The algal bloom, though, seemed preordained because of a combination of generally warming waters in a lake that has been slowly infused with pollution. The big pollutant is phosphorus, which the bacteria that cause algal blooms feed on. (A generation of science journalists have hated this, but phosphorus — the villain in many situations — is a so-called “nutrient.”) These nutrients are found in human sewage leaking into the lake from broken septics or inadequate wastewater treatment systems, and from soil scuffed into the lake from construction that puts more dirt into the lake than it can naturally handle.

The Jefferson Project, which has made a name for itself studying the lake, is trying to pin down whether the algal bloom was thanks to the pollution or thanks to some combination of natural events, like unseasonable warm and still waters. They gave an update to the Lake George Park Commission on Tuesday morning.

One of the project’s leaders, Rick Relyea, said once there is one algal bloom, the chances of another go up, but the cause matters a lot.

So far, there aren’t a whole lot of answers to what caused this one. One of the project’s key technologies for monitoring the lake — a floating, water-quality measurement station known as a vertical profiler — wasn’t in the lake when the bloom started, though it was then quickly put in the water. Instead, the bloom was spotted with human eyes and made public first by another one of the lake’s watchdog nonprofits, the Lake George Association.

If the Jefferson Project does reach a conclusion about cause, it will be interesting to see what officials around the lake do with that information.

A few weeks ago, I spent a long time talking about the bloom with Eric Siy, the head of the Fund for Lake George, which is a partner in the project.

Siy is trying to balance activism, which is his background, and science, which is the goal of the Jefferson Project.

“Was this a freak occurrence or is this a harbinger of things to come?” he said. “We don’t know yet, but we’re very confident that the science will light the way forward as needed, because otherwise we’re feeling our way in the dark.”

For years, there have been warnings that too much phosphorus would cause algal blooms. If the project says this year’s bloom was because of pollution, that would certainly accelerate a push to regulate lakeside septic systems, which are known to leak.

But if the project says this year’s bloom was primarily because of other things, things like warming water that are beyond local control, will that hurt momentum that’s been building to do more to inspect septic systems around the lake?

That shouldn’t happen, Siy told me.

“There are ‘no regrets’ actions we are taking. Reducing nutrients is a good thing no matter what,” he said. ‘Will that in turn be the solution to what just occurred? We don’t know that yet, but we do know that reducing nutrients is beneficial.”

Kristen Wilde, director of education for the Lake George Association, samples the algal bloom. Photo courtesy of Lake George Association

Editor’s note: This first appeared in Ry’s weekly “Water Line” email newsletter. Click here to sign up.