The Charles River, despite past improvements, has stalled in its progress toward becoming consistently swimmable. Polluted ...

Meanwhile, he’s earned support from the Charles River Watershed Association, a conservation group that collects more than 50,000 pounds of litter from the river each year.

The river received its highest mark in 2013, when it received an A-. That year, the Charles River water quality was safe for boating 96 percent of the time and safe for swimming 70 percent of the ...