Experts are warning that many more ponds could be closed this summer compared to past years, that’s because toxic blue-green algae blooms seem to be getting worse: affecting more ponds, for longer periods.
CAI’s climate and environment reporter Eve Zuckoff has been tracking the story and has information on what you can do to stay safe. She talked with Morning Edition Producer Brian Engles. Here’s their conversation.
Brian Engles: Why is toxic blue-green algae here in the first place and why are people so concerned about it?
Eve Zuckoff: Well to be clear blue-green algae — which is also known as cyanobacteria — is a natural part of our local environment; it forms the base of the food web, so the fact that it’s here in many of the thousand ponds on Cape Cod isn’t a concern. But the problem is that it can grow and grow and grow until it produces toxins that can irritate people’s eyes, and stomaches, and even lead to liver damage and neurological damage. It’s one of the most toxic natural substances known to man.
And to grow, it needs two things: heat and nutrients, especially nitrogen and phosphorous.
Now, unlucky for us: climate change is warming local waters. And the nutrients in our septic systems and lawn fertilizers are running off the land and making their way into our ponds and bays in excess. So we’ve got this double whammy going.
Brian Engles: What’s going on with the ponds that’s making them worse than past summers?
Eve Zuckoff: Well experts are still trying to really figure out why we’re having such a bigger, faster start than prior years — why, for example, cyanobacteria forced warnings at Mashpee-Wakeby Pond weeks earlier than anyone imagined and some of its toxin levels are so high. But they’ve noted some important things.
First: this past winter, we didn’t have a hard freeze. We didn’t have ice cover on ponds that’s important to naturally kill some of the algae. So the base levels of cyanobacteria going into summer were probably high.
And second, there’s a theory that Andrew Gottlieb of the Association to Preserve Cape Cod laid out for me. He said you know since COVID, we’ve seen a major population increase on the Cape, and the consequences are coming to roost:
Andrew Gottlieb: The simple way to say it is with more people for longer periods of time, producing more septic waste and more nitrogen that's finding its way through the groundwater into our estuaries and ponds. And now we're seeing the effects of that now.
So he says that ponds that were kind of on the edge in past years are finally expressing their potential with cyanobacteria growth and they’ll continue to.
Brian Engles: So what should people be looking out for to stay safe?
Eve Zuckoff: Color. Cyanobacteria will typically make water look bright green, teal; occasionally red or brown. But importantly, you’ll see it down through the water column, which is distinct from pollen, which is yellow-green and floats mostly on the surface. It also might smell or taste bad, like rotting plants.
And it seems to be extra problematic right after rainstorms. Experts believe rain is carrying nutrients from fertilizers and septic systems into our ponds and mixing with lurking cyanobacteria.
Brian Engles: Are there ponds in particular that people should be careful around?
Eve Zuckoff: Yes and no. There are ponds we see issues in summer after summer. So Walkers Pond in Harwich, Cliff Pond in Brewster, Santuit Pond in Mashpee, but it’s really hard to predict. Hundreds of ponds — dozens more than previous summers — could be vulnerable depending on how hot and wet this summer shapes out to be.
Really, the best thing people can do if they’re swimming at a public pond is read the signs posted, and if you see those visual cues that we talked about, contact APCC or your town health department and maybe stay out until it clears.
