Why Portland’s Approach to Stormwater Management Matters

Conventional approaches to stormwater management run the risk of contamination or flooding. Can community-level efforts to reform stormwater management systems overcome those challenges?

Portlanders flocked to a block party at the sectioned-off intersection of 7th Avenue and Sandy Boulevard in the Southeast District of Portland, Oregon. Vendors selling T-shirts and jewelry lined the event’s perimeter, while bands performed on a stage. A local politician mingled with residents, courting their votes for a council election. Skateboarders weaved through the crowd, utilizing a makeshift skate park at the bottom of the sloped street. 

Ted Labbe sported a sunhat as he headed the party’s central tent. He nodded as he heard comments from locals about their thoughts on traffic. One neighbor shared her experience with a high-crash road before the city added a crosswalk. 

Labbe turned the focus of the conversation to a map of a projected renovation of the intersection, complete with a pocket park, a playground, and increased tree canopy. This was the third annual block party for Depave, a nonprofit that tears up pavement to create green spaces. The goal was to inspire the community to reimagine the intersection and refine the plan according to feedback. With the projected ramifications of a warming climate, Depave's work, and the work of organizations like it, may now be more urgent than ever.

Labbe is the co-director of Depave. The nonprofit has completed over 80 projects since 2008, turning spaces it considers “over-paved” into rain gardens, bioswales, and parks, with 7th and Sandy its first project targeting a street. The group's ambitions run the gamut of addressing climate change, improving infrastructure, and social justice.

“Spaces that typically are over-paved and less integrated with green space in urban areas are a result of a long legacy of historic disenfranchisement,” said Katherine Rose, communications and engagement coordinator for Depave.

Stormwater management is one of Depave’s reasons for being. The nonprofit is one of many agencies in the city involved in creating greener stormwater management systems. The community-oriented nature of this project is a microcosm for Portland’s larger efforts to manage flooding. Labbe, a self-professed “stormwater geek,” lit up as he spoke of an element of the intersection’s redesign at the bottom of the slope.

“One really cool thing is that this is a low spot in the landscape,” Labbe said. “And if we can figure out how to create green stormwater management here, we can infiltrate runoff from acres of impervious area, so it's a strategic spot from a stormwater mitigation perspective.”

Labbe was referring to building a bioswale, a small, plant-filled channel that infiltrates stormwater runoff. It is one of many stormwater management solutions that fall under the umbrella of green infrastructure. 

Green infrastructure, sometimes called blue-green infrastructure, is an approach to stormwater management that aims to absorb stormwater within a city, rather than funneling it into a sewer system. It can include bioswales, rain gardens, eco-roofs, and pervious pavement.

The approach has received increased attention in recent years, as several scientists have projected flash flooding may increase with climate change. Some cities consider it an economical way to reduce the load a city’s combined sewer system handles during a heavy rain event, combatting both flooding and combined sewer overflows.

The “green” part of green infrastructure (native plants) cleans runoff, which would otherwise accumulate pollutants as it funnels into a river basin, thereby helping preserve wetland habitats. 

“What that research showed was that you couldn't engineer your way out of [increased flooding], just using floodwalls and levees and pumps and tanks and bigger and bigger pipes,” said Colin Thorne, a former geography professor at the University of Nottingham, discussing his early research into urban flood management. “Those would be overwhelmed, so we needed something else, and that something else was blue-green infrastructure.”

One example of a small-scale stormwater management project involving Depave was the replacement of parking spaces with rain gardens at the Stonebridge Apartments in Southeast Portland, a collaboration with the Johnson Creek Watershed Council. The apartments were built on inclines, so water flooded the lower floors during rain events. The rain gardens were added in early 2024 to soak up runoff. 

In the 1990s, Portland became an early leader in green infrastructure by addressing rampant combined sewer overflows into the Willamette River and Columbia Slough. These overflows happen when heavy rain overwhelms the city’s sewer pipes, leading to flooding in rivers and streams.

After a nonprofit sued the city in 1991, Portland tackled these overflows by creating the “Big Pipe,” which involved a network of large pipes that added capacity to the city’s aging sewer system. This project contributed to both Portland reducing its yearly overflows into the Willamette by 94% and higher sewer rates for residents. 

“The first part of the Big Pipe project was addressing the outfalls that went into the Columbia Slough,” said Maggie Skenderian, a retired Portland Bureau of Environmental Services employee who played a key role in spearheading Portland’s green infrastructure efforts. “My job was to manage community concerns about the construction. We set up a hotline, did newsletters and explained what was going on.”

Unlike many other cities at the time, Portland understood the drawbacks to only relying on pavement and gray infrastructure to manage stormwater. As part of Portland’s efforts to address flooding and overflows, the city's Bureau of Environmental Services initiated several projects to restore city floodplains to their pre-development state. 

Skenderian managed the floodplain restoration plan for the Johnson Creek watershed, which was flooding on average once every two years before the restoration plan. She had a front-row seat to the challenge of pursuing large-scale green stormwater management while trying to foster engagement and respond to community interests. As she recounted her decades of work in this domain she often defaulted to her catchphrase: “You can't make this shit up.”

A few Sundays every year, Portland closes off several roads to cars to create a bike path, and one year, the parking lot of the recently restored Foster Floodplain Natural Area (part of the Johnson Creek Restoration Plan) was added to the route. To increase community engagement in floodplain management, the agency started handing out paper “fish hats” affixed to bike helmets with colorful streamers on the back. 

“I know it sounds goofy, but people saw these folks with these funny hats with the streamers and everybody wants to know where they got them,” Skenderian said. “So, they come to our table for the Foster floodplain, and, don't you know, year after year after year, everybody wants to go to the place where they get the fish hat and go riding a bike.”

One of the unique facets of Portland’s restoration of Johnson Creek was the city’s purchase of over 60 residential parcels to serve as the base for the large-scale restoration projects. This involved extensive negotiations with landowners. 

Hal Nelson is a professor of public policy at Portland State University. He co-authored a paper on taxpayers’ preferences for green infrastructure in Portland, which found that survey respondents who trust their neighbors have over two times higher chances of accepting green infrastructure enhancement projects compared to those who don’t. 

“Trust is the lubricant for society, and it's easily destroyed,” Nelson said. “Economists talk about financial markets, but I think we also need a trust market.”

Portland’s culture may play a role in the relative success of its green infrastructure initiatives. Many of Portland’s green infrastructure projects, from bioswales to rain gardens, are constructed on residential properties and voluntarily maintained by homeowners. According to Derek Palmore, who worked for the program, these volunteers—called Green Street Stewards—maintain 640 green infrastructure projects, amounting to 20% of all such facilities in the city. 

According to Nelson, the three regular topics of conversation at a Portland house party are “beer, bikes, and bioswales.” Skenderian reasoned that sometimes Portland’s nature-loving vibes can even go too far. 

“Portland never met a tree it didn’t like,” Skenderian said. “To be honest, in some cases, there were people who wanted to push things so far that it was problematic.” She described individuals who worked for the Bureau of Environmental Services who would shoehorn environmental visions that were barely related to stormwater management into floodplain restoration projects. 

Emily O’Donnell is a professor at the University of Nottingham who worked with Thorne to study green infrastructure in Portland in 2014. She remarked on Portlanders’ willingness to accept green infrastructure. 

“I think everyone from the U.K. who goes to Portland sees what they're doing in Portland and thinks, ‘Why are we not doing it in the U.K.?’” O’Donnell said. 

The often-imaginative nature of Portland’s stormwater management is on full display at the East Multnomah Soil and Water Conservation District building in Northeast Portland. Soil and water conservation districts are small units of government that provide resources and guidance to help individuals and organizations manage their soil and water.

“When we first bought this place, a few of these trees were here, but otherwise it was all grass,” said Kathy Shearin, the urban lands program manager for the agency. “So, what we first wanted to do was remove a bunch of the grass and install a native landscape that shows people the types of plants that can grow in various microclimates.”

The abundance of sedges, shrubs, and old trees is hard to miss upon entering the grounds of the building. But the renovation of the facility to display a host of stormwater management techniques didn’t stop there. 

The building’s parking lot and walkways are paved with pervious concrete, which allows greater stormwater infiltration. The building’s downspout features an artful cascade of buckets filled with plants (which soak up water from the downspout via capillary action) that terminate in a rain garden instead of a sewer drain. Sedum, a type of succulent, adorns the roof, forming an eco-roof to catch stormwater.

“Portland is green, and people come here for that,” Shearin said. “I personally cried when I came here from Arizona, where it was in drought. I just felt alive for the first time.”