CSO Notification

In accordance with Massachusetts Regulation 314 CMR 16.00, the City of Fitchburg is required to provide public notification in the event of certain types of untreated or partially treated wastewater, including discharges that fall into the categories of combined sewer overflows (CSOs), sanitary sewer overflows (SSOs), and blended wastewater. Click here to view a map of the combined sewers in Fitchburg. To subscribe to receive notifications, or to see if there are any active alerts related to the discharge of untreated or partially treated wastewater, please use the following link:

Wastewater Alert Center


CSO Final Notification Plan

Please Note: For a Spanish translation, go to the bottom right of the web page and click "Select Language", then select "Spanish".

Para una traducción al español, vaya a la parte inferior derecha de la página web y haga clic en "Seleccionar idioma", luego seleccione "Español".


CSO January 24JPG

Note: data provided in the table above is preliminary and subject to change.

For past CSO Notification Events, please click here .     


A combined sewer carries both rain water runoff from streets, and sewage from homes and businesses.   During dry weather, the sewage in a combined sewer system is treated at the City’s wastewater treatment plant.   During rain events, combined sewers release a mixture of rain water runoff and raw sewerage to the Nashua River.   The purpose of the releases is to prevent backups of the downstream sewer system and flooding of the City’s wastewater treatment plant. Newer systems that carry street runoff and domestic sewerage in separate pipes became the norm after 1930, yet combined sewer systems are still very common in older cities such as Fitchburg.  Recognizing the threat that combined sewer systems still pose to water quality, the Federal Government passed the Clean Water Act in 1972, which made CSO discharges illegal.  Many older cities across the country are still trying to catch up to meet this requirement.

In 2012, the City of Fitchburg entered into a legal resolution agreement with the United States Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (MassDEP) to address key deficiencies within the City’s sewer system.  This agreement, called a Consent Decree, requires the City to perform various studies and infrastructure projects. One of the requirements of the Consent Decree is that the City eliminate Combined Sewer Overflows (CSOs) to the North Nashua River by the end of 2030.  To achieve this, the City developed their Combined Sewer Overflow Long-Term Control Plan in 2019. This plan created the City’s new sewer separation program, while reviewing environmental and social/economic impacts of the proposed sewer separation projects.

Between 1999 and today, Fitchburg has successfully separated over half of their combined sewers, and closed 50 of their 58 CSO discharge locations. To separate the remaining combined sewers and close the 8 CSO discharge locations, the City has five (5) upcoming sewer separation projects. These project areas can be seen on this map. The schedule of these projects is shown below:

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