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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority


The Charles River


Pollution sources to the lower Charles include upstream community wastewater treatment plants, contaminated stormwater runoff, leaking septic systems, and combined sewer overflow.

In the Charles, most fecal coliform bacteria counts do not exceed the state standard of 200 colonies per 100 milliliters. The area between the Watertown dam and the Arsenal Mall (upstream of any CSO discharges) is the most consistently contaminated section surveyed; and the Charles River Basin, the important recreational area between Cambridge and Boston, had the best bacterial water quality.

Download Charles River sampling data

Charles River sampling

larger map with sampling locations

All Harbor & river sampling locations

Download Water Quality Data

Boston Harbor's Tributary Rivers

Charles River Watershed Association