In 2021, a staggering 51 million gallons of untreated sewage surged into Alewife Brook. This stark fact underscores the ongoing struggle to protect this vital waterway. Alewife Brook, a small channel winding through Arlington, Cambridge, and Somerville, faces an enormous challenge. It’s a popular spot for recreation and commuting, yet it bears the burden of significant pollution.
Alewife Brook begins its journey at Fresh Pond. It then flows underground until it emerges near the Alewife T station. Here, it merges with the Little River and forms the boundary between Arlington and North Cambridge. The brook continues, marking the border between Arlington and West Somerville along the Alewife Brook Parkway. Its journey ends as it flows into the Mystic River, south of the Mystic Lakes. The brook meanders through densely populated areas and alongside the well-used Alewife Greenway Path. Despite its importance to the community, Alewife Brook suffers from untreated sewage pollution, largely due to Combined Sewer Overflows (CSOs).
These CSOs are a relic of older drainage systems. These systems combine stormwater and sewage in the same pipes. During heavy rain, the pipes overflow, releasing untreated sewage directly into the brook. All six CSOs that discharge into Alewife Brook release completely untreated sewage. In 2023 alone, 26 million gallons of combined sewage and stormwater flowed into the brook. This is a massive amount for a small waterway. To visualize it, imagine standing by the brook in average conditions. It would take five days for 26 million gallons to pass by. And by 2024, over 18 million gallons had already been discharged.
The consequences are severe. Studies have linked CSO events to gastrointestinal illnesses. The problem is exacerbated by the brook’s tendency to overflow its banks during storms. This can spread sewage-laden water into backyards and onto the Alewife Brook commuter path, posing a direct threat to public health. The impact of CSOs on Alewife Brook represents a significant environmental justice issue. The neighborhoods bordering the brook are disproportionately affected by this pollution, highlighting the urgent need for solutions. Groups like Save the Alewife Brook, the Mystic River Watershed Association, and the Charles River Watershed Association are working to address this problem and advocate for the elimination of CSOs in the area. They aim to improve water quality, protect public health, and ensure environmental justice for the communities surrounding Alewife Brook.