Probably the most prominent urban river in New England, The Charles River, is an 80-mile-long river that is a major source of recreation and a readily available connection to the natural world for residents of the Boston metropolitan area. The Charles River has historically suffered from industrial contamination – most of which has been directly caused by the densely populated area through which the river flows. The most prevalent one being excessive blooms of algae during the warm summer months, that can be toxic to animals and people.
Recent tests indicated that the Charles River contains high levels of blue-green algae, prompting health officials to advise people to exercise caution and refrain from coming in contact with the water. These blooms are caused by cyanobacteria, also known as blue-green algae. Exposure to this particular type of bacteria can cause symptoms ranging from skin irritation to vomiting.
Ferdi Hellweger, a water quality expert and an associate professor of civil and environmental engineering at Northeastern University, talks about the Charles River and explains how this setback could impact the efforts to make the Charles River swimmable. “These blooms are threatening our vision of a swimmable Charles and are impacting other recreational activities around the river, including dog walking,” says Hellweger. The Charles River is not alone in this regard. Increased occurrences of harmful algal blooms are a worldwide trend recorded from over a span of years from Ohio to Ontario and others.
It’s hard to pinpoint how these cyanobacteria bloom, though. People are quick to point to increased phosphorus input as a culprit—and while it’s true that cyanobacteria need phosphorus to grow, and that controlling phosphorus input is a good practice in general, it’s unfortunately not that simple. Some say cyanobacteria blooms are natural and some human activities (such as agriculture or a poorly functioning septic system) can make blooms more likely. The solution? Hellweger says improving basic research into the ecology of cyanobacteria and a cautious approach when considering massive and costly management actions.