Stormwater in New Haven


(c) Chris Banks / Wayworks


New Haven in recent years has significantly reduced its point source pollution—pollution coming from a single, identifiable source like a gas station or a household. But the Long Island Sound is still plagued by nonpoint source pollution like stormwater runoff and combined sewer overflows (CSOs). The majority of New Haven is covered with impervious surfaces like roads, buildings, and parking lots that generate a lot of stormwater runoff, especially during large rain events.

In combined sewer systems, like that of the West River watershed, stormwater doesn’t drain into a separate set of pipes, but mixes into the sewer system. This water is carried to the treatment plant and discharged into the Sound. During most storm events, especially when the rain is heavy, water overloads the system and a mixture of sewage and stormwater drains directly into the West River (and other urban waterways).

These challenges present a unique opportunity for researchers at Yale School of Forestry & Environmental Studies to test the effectiveness of green infrastructure, like bioswales, in New Haven. 

New Haven’s bioswales are located on sidewalks and capture stormwater as it flows down the street during rain events. Stormwater enters the bioswales through a curb cut, allowing the vegetation and soil to absorb the runoff. The approach relies heavily on community engagement to partake in understanding, designing, caring for the bioswales through direct contact with adjacent property owners, educational signage for many of the bioswales, and posting monitoring results on the URI website.