The Mystic River is cleaner today than it was fifty years ago thanks to the Clean Water Act, but some pesky pollution problems remain! One solution to this problem comes in the form of “green infrastructure” — built solutions that mimic how nature filters out excess nutrients by letting rainwater drain slowly through the soil. In 2024, MyRWA worked with cities and towns to expanded the construction of a particular type of green infrastructure underneath our roads called a stormwater infiltration trench.
Flyer incorporating student-made designs announcing green infrastructure installation
This past year, we worked with municipalities to install over 50 trenches in the Towns of Arlington and Winchester and the City of Medford with funding from the U.S. Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (Mass DEP), building upon initial successes in Lexington, Arlington, and Melrose. All told, we have constructed over 120 trenches across the watershed with even more potential locations sited.
STORMWATER POLLUTION
Stormwater is another word for rain and melting snow. Stormwater Pollution happens when the water picks up pollutants, flushing them down the nearest drain. Pollutants are then transported through the underground pipe networks directly to our lakes, rivers, and streams.
One particularly impactful pollutant in stormwater is phosphorus, which comes from dead plants and leaves, fertilizer, and other organic waste. Phosphorus can cause toxic algal blooms that are dangerous to people and deadly to pets. They can also speed up the growth of invasive plants, and reduce the amount of oxygen in the water that fish need to breathe.
As more and more open space land is developed and covered by impervious surfaces (surfaces where water cannot penetrate), stormwater cannot soak into the ground and is forced to become runoff. The more urban communities—those with less open space and extensive development and paving—are disproportionately impacted by stormwater pollution.
STORMWATER INFILTRATION TRENCHES
Stormwater infiltration trenches are a simple solution to combat stormwater pollution. They are built along with the existing stormwater system underneath the road and work by redirecting the first dirty flush of stormwater that comes off of the street when it rains into the soil rather than into the river. There, the phosphorus is filtered and reabsorbed just like it would in nature. To learn more about how infiltration trenches work, watch the video below:
Stormwater infiltration trenches are most effective at a large scale, and we have been working to construct them in cities and towns across the watershed. Alongside other types of green infrastructure like rain gardens and constructed wetlands, they can make a big difference in the amount of pollution reaching the river.
Luckily, constructing stormwater trenches causes little disruption to neighborhoods and traffic, and they are invisible once they are installed. However, since you can’t see them around the city, we wanted to make the invisible visible with the storymap and interactive map below:
new education programming
We have also been sharing the story of infiltration trenches and green infrastructure in the classroom. Members of the education team developed a new curriculum on infiltration trenches. We demonstrated how an infiltration trench works using a model in the classroom, with help from local engineers! Students then created educational signage that MyRWA staff and student group volunteers used to spread awareness of new construction. Learn more about our education programs here.
Town engineers in Medford visit Missituk Elementary to demonstrate how an infiltration trench works using a working model constructed by MyRWA’s summer fellows. Credit: Natalia Bayona
This project has been financed with Federal Funds from the Environmental Protection Agency (EPA) to the Massachusetts Department of Environmental Protection (the Department) under an s. 319 competitive grant. The contents do not necessarily reflect the views and policies of EPA or of the Department, nor does the mention of trade names or commercial products constitute endorsement or recommendation for use.
