CSO Overview

One major type of on-going construction, and the reason you see streets around the City undergoing a transformation, is that of our Combined Sewer Overflow (CSO) projects.

As required by the US Environmental Protection Agency (EPA) and the New Hampshire Department of Environmental Services (DES), the City is implementing the elimination of our CSOs by separating the sanitary wastewater system from the stormwater system under a schedule which will have all CSOs eliminated by 2020. 

The City is incorporating this work into other infrastructure projects in order to cost effectively address the City’s needs for the future.