How do CSOs and stormwater discharges impact you?

During large storms, CSOs discharge to the Alewife Brook, the Charles and Mystic River.

CSOs are mostly stormwater but do contain sanitary wastewater, and discharge bacteria, nutrients, and other pollutants into waterways.

This can impact water quality and recreational uses during and immediately following those heavy rain events.

Stormwater from separate systems also impacts water quality and causes flooding. CSOs do not cause flooding but do contribute additional pollutants to stormwater contamination.