Folder Resources Categories Folder Arlington Community Electricity (ACE) Folder Artificial Turf & PFAS Folder Campaigns Folder Climate & Environmental Groups (Local) Folder Climate Change (aka the Climate Crisis) Folder EcoFest Arlington Folder Electrify Arlington Folder Home Energy: Efficiency & Renewables Folder Lawn & Garden Practices for a Healthy Ecosytem Folder Mystic Charles Pollinator Pathways Group [Resources] Folder Net Zero Folder News Sources: Climate, energy, environment Folder Pesticides (Impacts, Legislation) Folder Save the Alewife Brook (www.savethealewifebrook.org) Folder Sustainable Arlington Resources Folder Town Websites Folder Transportation Documents Search for documents Find by title or description… Search Reset default MWRA's CSO (Combined Sewer Overflow) Reporting: Alewife Brook Published on 26 October 2021 Tagged in AlewifeBrook, CSOs, pollution, stormwater Download A combined sewer overflow (CSO) occurs when a large storm overwhelms the sewage system causing rainwater to mix with wastewater and discharge to a nearby water body. This relief measure prevents sewage backups into homes and businesses. MWRA owns combined sewer outfalls that discharge to the Charles and Mystic Rivers, Alewife Brook, and Boston Harbor. When a CSO occurs at an MWRA-owned outfall, there is a notification displayed on the map below. The cities of Boston, Cambridge, Chelsea and Somerville manage their own combined sewer outfalls, including CSO reporting. These communities must be contacted directly for information regarding their CSO discharges. To see where all CSO outfalls are located, download this map of MWRA and community CSO sites. Public health officials recommend avoiding contact with water bodies during rainstorms and for 48 hours afterwards, as there may be increased health risks due to bacteria or other pollutants associated with urban stormwater runoff and CSO discharges. Subscribe to MWRA CSO discharge notifications