Portland is cleaning up the watershed with green infrastructure

Sunny marsh marigolds and grasses grow together in a rain garden at Sagamore Village. Portland Public Works selected locally native plants known for their resilience to drought and flooding, and grouped them by their light preferences.

Sagamore Village is a public housing community in Portland where kids play soccer on the green and residents grow tomatoes in the community garden. Up until this past spring, it was also a place where every time it rained, stormwater rolled off the streets, bringing a toxic mix of fertilizers, pet waste, road salts, litter, and other pollutants into nearby Capisic Brook. All this stormwater was unhealthy for the fish and wildlife there, as well as downstream in the Fore River and Casco Bay.

The answer to stormwater pollution at Sagamore? Rain gardens!

Over the past year, Portland Public Works transformed Sagamore with the installation of 32 rain gardens, also known as bioretention cells. These gardens, nestled along the curbs, are designed to filter pollutants from stormwater. Vibrant flowers, shrubs, and grasses do the heavy lifting, soaking up excess nitrogen and phosphorus. Beneath the surface, layers of soil, sandy loam, clay, and stones work together to cleanse the water before it reaches Capisic Brook. Some of the gardens are intricate, featuring sloping entrances, sharp turns, and steel spillover walls that guide the water through a maze-like path.

A rain garden installed near Kennedy Park in Portland does its job of filtering out stormwater pollutants after a heavy rainfall in June.

The rain gardens can’t do it alone.

However, the rain gardens can’t function without regular maintenance. Portland’s Public Works employees, alongside volunteers and local residents, ensure the gardens remain effective. Ray, a nearby resident, keeps a watchful eye on one of the gardens. “A lot of cigarette butts,” he grumbles, “but I’m getting used to it.” Twice a year, Public Works crews clear out tons of sand, soil, leaves, and debris, much like cleaning a kitchen sink trap.

Funded by Portland’s stormwater management fees, the city invested $2 million in Sagamore’s 32 gardens to treat 17 acres of Capisic Brook, which is currently classified as an urban impaired stream. This investment is crucial for improving water quality, not only for Capisic Brook but also for the downstream marine environments that many, including local fishermen, depend on.

Road salt presents a challenge for these gardens, as it can damage the plants and soil that usually filter out pollutants. As salt washes downstream, it harms freshwater streams like Capisic Brook. The City is working to reduce road salt use, but they need to find a balance between keeping roads safe and protecting water quality. Residents can pitch in by shoveling more often and using less salt on sidewalks and driveways.

Portland’s Senior Water Resources Engineer Justin Pellerin, began planning the Sagamore rain gardens five years ago, navigating funding and pandemic hurdles along the way. Justin says that when it finally came together and installation began in 2023, “We were excited to see what green infrastructure could do on a larger residential scale.”

It takes a village…and streams, wetlands, and forests.

Doug Roncarati, Portland’s Stormwater Program Coordinator, acknowledges that maintaining these systems is costly. It is much easier and more affordable in the long run to conserve natural stormwater systems before pollution becomes a problem. This is why he is excited that the city recently conserved wetlands at the headwaters of Capisic. Doug would like to see more cities and developers using Low Impact Development (LID) techniques that minimize pavement, keep waterways intact, and rely more on nature’s filtering powers.

“It’s not just about putting in green infrastructure to treat stormwater,” he says, “it’s about protecting streams, wetlands, brooks, and forests. Even the best systems we can put in don’t compare to natural systems. Let’s protect what we have first, then build stormwater management systems to reduce pollution.”

Portland’s Stormwater Program Coordinator Doug Roncarati reaches into a rain garden to pull out a piece of trash.

Casco Baykeeper Ivy Frignoca remarks, “We love the holistic approach the city took, looking for ways to improve water quality by protecting headwaters and putting in natural gardens that beautify the neighborhood, filter pollutants from water, and make it safer for children to play in the water.”

Capisic Brook, near Sagamore Village, Portland.

Rain gardens bring other benefits to Sagamore.

Rain gardens do more than clean water—they beautify Sagamore and calm traffic. The next phase of the project will add sidewalks, making the community more accessible and welcoming.

As Capisic Brook flows quietly by, it reflects the pebbles at the bottom, a testament to the power of nature and thoughtful urban planning. If you listen, you might hear a fish splash “Thank you.”