Sanitary Sewer Overflows (SSOs) can occur during heavy or prolonged rain events and discharge stormwater mixed with untreated sewage.
Three known SSO discharges were active on March 7, 2011:
Wedgemere Station in Winchester on the Aberjona River
Overflow at Horn Pond in Woburn
Mystic Valley Parkway in Arlington to Lower Mystic Lake
Discharges from SSOs contain levels of bacteria, viruses, raw sewage and other pollutants that may pose health risks to people who come in direct or indirect contact (e.g. contact with pets swimming in contaminated water). Contact with SSO-contaminated water should be avoided. Additional information on SSOs in the Mystic River Watershed can be found at http://mysticriver.org/sso/.
Based upon ten years of water quality data collected on the Mystic and its tributaries, MyRWA recommends that whenever it rains people should revise their water-based recreation plans such as boating, fishing, or swimming on the Mystic. In general “wet weather” conditions are a high level predictor for poor water quality in the Mystic watershed from various pollutant sources. These poor water quality conditions can occur whenever it rains regardless of an SSO or CSO event due to stormwater runoff and local plumbing problems (illicit connections). Bacterial contaminants typically last for 48 hours. Community boating programs should post flags or other visual indicators to inform citizens that water quality does not support active recreation at that time.
Fish Consumption Advisory
It should also be noted that the MA Department of Public Health has issued a fish consumption advisory for several rivers and ponds in theMystic River watershed against consuming fish caught in these waters For more information, contact MDPH Bureau of Environmental Health at 617-624-5757. Please advise people you see fishing in the Mystic or its tributaries that fish caught should not be eaten.