Portsmouth Sewer Division Introduces New Twitter Feed About CSOs

February 27, 2018

To better keep residents apprised of occurrences of combined sewer overflows (CSOs), the Portsmouth Sewer Division has introduced a Twitter feed, @PortsmouthCSOs, which will alert the community of overflows in real time.

CSOs are common to older combined sewer and storm water collection systems throughout the country. CSOs are relief points in the combined sewer systems that provide for discharge (or overflow) of combined sewage and stormwater into a nearby waterway. A “CSO event” can occur during a heavy rainfall or snowmelt when stormwater overloads the system. The untreated sewage and stormwater may be discharged at CSO locations during an event.

There are three active CSO locations in the City that are permitted by the Environmental Protection Agency:

  • CSOs No. 10A and No. 10B are located adjacent to Parrott Avenue and discharge to South Mill Pond. This is a tidal pond that flows to the Piscataqua River.      
  • CSO No. 013 is located at the end of Deer Street and discharges to the Piscataqua River.

The Portsmouth Sewer Division has measuring devices in each CSO location. When a CSO event occurs, the device will automatically send a tweet to @PortsmouthCSOs to make residents aware of the event. 

The City has posted signs at each CSO location, and proceeded with this new notification process following a request by City Council. “We appreciate the City Council’s efforts in seeking an improved system to inform the community of these occurrences more effectively,” said City Engineer Terry Desmarais. “This Twitter feed will ensure any interested resident is informed of a CSO event immediately and reduce any confusion of what actions to take during these occasional events.”

There may be instances where the devices misread an event, in which case staff will issue clarification to the public. Residents are encouraged to visit https://www.cityofportsmouth.com/publicworks/wastewater/combined-sewer-overflows-cso for full background on CSOs, their locations and what to do when an event occurs. This site also provides validated data on CSO volumes discharged on monthly basis.