State public health officials have issued a health advisory —and posted warning signs along the lower basin of the Charles River urging people to avoid contact with the water, rinse thoroughly if they do come into contact with it, and refrain from drinking it.
The warning comes courtesy of a spike in the level of blue-green algae—or cyanobacteria—in the water, which has been measured at twice the acceptable limit. So just what exactly is cyanobacteria? What’s it doing in the Charles River? And what exactly is the threat it poses?
For answers, I met up with Julie Dyer Wood , director of projects for the Charles River Watershed Association, on the banks of the river Charles, near the MIT Sailing Pavilion in Cambridge.
The first thing I learned is that even when the river that inspired the Standells to pen "Dirty Water" isn’t particularly dirty, it still should look a little dirty.
"The tea-brown color is normal for the Charles," she explained. "But, what we're seeing today is much more of a green, pea-soup color."
The green tint—and perhaps one of the reasons why we saw not a single boat on the water on a beautiful late summer morning—is thanks to that recent bloom of so-called blue-green algae in the water. For the record, it's not actually an algae at all, but a cyan-colored bacteria appropriately called cyanobacteria.
"What we have in the Charles right now is an unbalanced system," Wood said. "The cyanobacteria is allowed to grow so prolifically that it is out-competing other species and taking over."
This is not uncommon, especially in the summertime. Cyanobacteria is present in most fresh water bodies at low levels. But it loves ponds and lakes in the summer—the stiller and warmer the water the better. And for a river, the water on the Charles is remarkably still. Wood says even more so this year thanks to the drought.
"The lower Charles River is dammed on both ends," she said. "In many ways the lower Charles River Basin acts more like a lake than a river."
Now before you go denigrating this little blue-green bug, consider that long before there were people fishing and boating in the Charles—heck, eons before there were even people or a Charles River—cyanobacteria was here.
"They’ve found evidence of fossilized cyanobacteria going back approximately 3.5 billion years," said Jim Haney , a biology professor at the University of New Hampshire.
Not only is cyanobacteria one of the oldest living things on Earth, it also helped create the Earth as we know it today.
"They were the organisms that invented photosynthesis it appears," he explained. "There was little or no oxygen, and their photosynthesis contributed to the poisoning of the earth with oxygen, if you look at it from their perspective."
It’s not a stretch to say that all higher life—from dust mites to you and me, owes a hefty debt to the little microorganism. But we live in a what-have-you-done-for-me-lately world. And these days, it's not about what cyanobacteria did for us—but what it can do to us.
"They can produce—depending on the species that we see—different types of toxins. Typically, neurotoxins that would affect the brain or nervous system or hepatotoxins that would affect the liver," said Woods.
It’s those toxins that can make us sick, and why state officials have issued the warning. The most immediate danger comes when contaminated water is ingested. That can cause everything from dizziness to vomiting to liver failure in people—and animals.
"Typically, when deaths are attributed to cyanobacteria it’s in dogs—not humans," said Wood.
Just touching the toxins can irritate the eyes or cause skin rashes, so swimming is out—for people and their pets. Officials say if you do come into contact with the water, rinse thoroughly.
Emerging science from Haney and others has showed that the toxins can also be present in low levels in the air around the water.
"That’s something that we’ve found very recently: The presence of toxins in the atmosphere as aerosols," said Haney. "We’re looking at the factors that contribute to the release of these toxins."
Haney’s research suggests that any significant effects from airborne toxins likely comes only from exposure over long periods of time. He stresses it’s only a hypothesis, but he’s been investigating whether that long term exposure could contribute to increased rates of neurological disorders like Parkinson’s and ALS.
"We are in fact investigating lakes that have clusters of ALS patients around them to see if there is a connection," he said. "At this point in time it’s inconclusive."
In the meantime, Haney says there’s no need to panic, but do use common sense and a little caution whenever you find yourself near still, green waters.
As for how much caution needs to be taken here on the Charles, Wood hopes people will heed the warnings, and educate themselves on the issue. But ultimately, she says, it's up to you.
"There are folks that will choose to continue their regular activities, go out and row every single day," she said. "And then there are folks who will avoid the Charles because they are more risk averse and any exposure, to them, is too much."
The toxins can be present for a few weeks after cyanobacteria levels begin to normalize, which is expected to happen in a few weeks. Officials will continue to measure and monitor the cyanobacteria levels in the Charles weekly.
