Many Bostonians thought they’d never see children swimming in the Charles River, and the fact that the waterway was briefly open to public bathing this past summer showed how much progress there’s been in cleaning it up. However, the sight of kids frolicking in the Charles doesn’t mean all the river’s problems have been solved. Several environmental groups, including the Conservation Law Foundation and American Rivers, have petitioned the Environmental Protection Agency to close loopholes in regulations that allow for urban runoff from private entities with buildings built before the Clean Water Act of 1972. If Greater Boston wants to keep improving the swimmability of the Charles, the region needs to keep chipping away at the runoff problem. Fortunately, there are options.
Urban runoff is the process by which rainwater collects pollutants from city streets and then deposits them in local waterways. In less developed areas, this water soaks into the ground, where it is purified by natural processes. However, traditional cements are impermeable, so water that falls on them can’t be cleaned naturally before it collects in rivers and streams. The substances found in this runoff — which range from toxins from car exhaust to nutrients from lawn fertilizers — can dramatically change river ecosystems by poisoning aquatic life and causing huge increases in algae populations, tiny organisms that deoxidize the water after they die.