Green Infrastructure in the Mystic River Watershed
Using nature-based solutions to clean up stormwater pollution
Welcome to the Mystic River Watershed!
The Mystic River runs from the bottom of the Mystic Lakes in Medford and Arlington out into Boston Harbor.
The Mystic River watershed consists of the land area within which water will eventually drain into the Mystic River.
It connects 21 cities and towns, and dozens of smaller rivers, streams, ponds, and lakes.
Before the cities and towns were here, the landscape of the Mystic River watershed was very different. Home to the Massachusett, Nipmuc, and Pawtucket tribes, it was covered in forests, meadows, and salt marshes.
In this environment, rain, or "stormwater," would soak into the soil and filter very slowly through the ground into a stream or lake.
The Mystic River in 1893 compared to the present day. Notice how many new streets and buildings have been built around the river!
Cities Change Rivers
Today, cities and towns have been built around the river, adding roads, roofs, sidewalks, parking lots, and other impervious surfaces that can’t soak up the rain.
Photo: Mark Peterson
This map represents the concentration of impervious surfaces in the Mystic River watershed
In areas with many impervious surfaces, stormwater can't soak into the soil. Instead, it runs over the roofs and pavement and down into the storm drains in the street.
Let's zoom in on a neighborhood in the City of Medford
To manage rain, the city has built a network of underground stormwater pipes...
When it rains, stormwater flows over the roofs, sidewalks, and streets, picking up any pollutants in its path, and entering the pipe network through storm drains...
Then, the pipes carry the polluted stormwater to outfalls that release it directly into rivers and streams.
We call this "Stormwater Pollution"
Stormwater Pollution
Stormwater Pollution happens when the rain picks up pollutants such as car oil, dog waste, excess fertilizer, herbicides and pesticides, salt and de-icing materials, cigarette butts, and other trash. These pollutants go down the nearest storm drain and end up in our lakes, rivers, and streams.
One major pollutant in the Mystic River watershed is phosphorus. In urban and suburban areas, phosphorus comes from leaves and grass clippings or the fertilizers we put on our lawns. Even though phosphorus itself is not toxic to humans, plants, or animals, too much of it in rivers and streams can cause a variety of impacts on the natural ecosystem. Aquatic plants and algae need phosphorus to grow, and the amount of phosphorus determines how much and how fast they can grow. When there is too much phosphorus, they can grow out of control.
Cyanobacteria Bloom on the Mystic River - Photo: Jack Bitney
Excess phosphorus promotes the growth of cyanobacteria - a type of algae that can release toxic chemicals that are dangerous for people and can be deadly to pets and wildlife. Phosphorus also speeds up the growth of invasive plants and can reduce the amount of dissolved oxygen, which makes the water unsuitable for fish and other wildlife.
In areas with lots of impervious surfaces, phosphorus can be easily swept into water bodies rather than soaking into the soil.
Green Stormwater Infrastructure
How do we reduce phosphorus?
One solution is to look back at how stormwater drains in nature, using soil as a natural filter to remove excess phosphorus and other nutrients. We call this type of solution Green Stormwater Infrastructure.
Here's an example. It's called a "Stormwater Infiltration Trench"
It works by redirecting the dirtiest first flush of polluted stormwater into the soil rather than into the rest of the drainage network. Soil acts like a natural filter, removing the phosphorus before it enters the water. Watch to learn more!
MyRWA has worked with the U.S. Environmental Protection Agency (EPA), the Massachusetts Department of Environmental Protection (DEP), and the Massachusetts Office of Coastal Zone Management (CZM) to site and build infiltration trenches in different parts of the Mystic River watershed.
Initial stormwater infiltration trenches were built in the towns of Lexington and Arlington, and later in Melrose.
Based on these initial successes and with funding from the Massachusetts Department of Environmental Protection (s.319 Grant) and the United States Environmental Protection Agency, over 50 more trenches were built in Arlington, Medford, and Winchester.
And, we have identified many sites with the potential for additional trenches in these same municipalities
Plus even more in cities and towns throughout the watershed.
Each infiltration trench is small and inexpensive, but at scale, they can make a big difference to the amount of phosphorus pollution reaching the river.
Infiltration trenches work alongside other nature-based solutions to manage stormwater throughout the watershed like rain gardens and stormwater wetlands, all of which contribute to cleaner rivers.
Our Vision
The Mystic River Watershed Association envisions a healthy, vibrant, and resilient Mystic River watershed for the benefit of all our community members. People deserve safe and open access to their local natural resources and an environment full of nature and free of pollution that supports their health.
Green infrastructure plays a role as an effective way of protecting our waterways from stormwater pollution. The Mystic River Watershed Association is committed to continuing to work with municipalities on projects like these to help make our watershed cleaner and safer for everyone.
You can help by supporting your local city or town when they implement new stormwater solutions and, when the opportunity arises, by voting "yes" to increased stormwater funding in your municipality.
Student-designed flyers announcing infiltration trench construction in Medford
