Some areas of Syracuse have sewers that carry both sanitary sewage—from homes and businesses—and also stormwater from the streets. During dry weather these sewers carry all the sanitary sewage to the Metropolitan Syracuse Wastewater Treatment Plant for treatment.

During times of heavy rain or melting snow, however, the amount of water is far greater than the capacity of the sewers. At these times, the sewers overflow and discharge the excess—a combination of runoff and sanitary sewage—into Onondaga Creek and Harbor Brook. These discharges eventually reach Onondaga Lake. This is combined sewer overflow (CSO). The sewer system was designed to overflow in this way to prevent sewage from backing up into streets and basements. WEP's Flow Control Division operates the major portions of Syracuse's combined sewer system and regularly inspects and maintains overflow relief points along Onondaga Creek and Harbor Brook.

Combined Sewer Overflow Notification

Onondaga County has created a web site at CSO-SaveTheRain to serve as a notification system to alert the public of the occurrence of  CSO events and as a prediction of elevated bacteria levels in Onondaga Lake and its’ tributaries.  This notification complies with New York State’s Sewage Pollution Right to Know Act (A.10585A / S.6268D) and complements Onondaga County’s efforts under the Save the Rain Program to reduce pollution to Onondaga Lake and its tributaries.

If you see a Combined Sewer Overflow (always marked with a sign) discharging during dry weather, please report it by calling 315-435-2260 and ask for "Flow Control."

A combined sewer overflow should never be active in dry weather.