Five years ago this month, The Nations was under water. More than 13 inches of rain had fallen in Nashville in 36 hours, causing waterways throughout the city to crest and spill over into nearby neighborhoods. Residents of The Nations, an industrial enclave west of downtown, had watched as Richland Creek came out of its banks, flooded homes and shopping centers, and forced some people to their rooftops. In all, the historic flood killed 11 people in Nashville and caused some $2 billion in damages to private property.

The Nations has long since recovered, and today it’s one of the city’s trendiest neighborhoods. Nashville is expecting 1 million new residents over the next 25 years, and given The Nations’ proximity to downtown, younger residents are making many of the old homes in the community new again. They are drawn to the area by its small-town charm -- its tree-lined streets with sidewalks and its brightly painted houses with front porches. Developers have arrived, too, putting up two houses on one lot and renting them out.

But one thing hasn’t changed: The Nations is still prone to flooding. “It wasn’t just a one-time issue back in 2010,” says Laurel Creech in the Mayor’s Office of Environment and Sustainability. “It’s a continuing issue.”

Nashville is hoping it can make The Nations more resilient to weather-related events by creating green alleys. The city has launched its first green alley project, whereby volunteers plant shallow rain gardens in residents’ backyards along alleyways. Generally, green alleys are designed to capture stormwater before it runs into nearby waterways and pollutes them. Under Nashville’s program, the goal is to have zero runoff from residential properties. Rain gardens will be planted over about 20 blocks; volunteers started planting them this spring and will continue into the fall. “It is my hope,” Mayor Karl Dean said in a statement, “that this project will become a successful model of stormwater mitigation that other neighborhoods can replicate.”

Nashville is just one of a dozen U.S. cities that have turned to alley greening projects in the past decade as part of a larger effort to create green infrastructure and promote sustainability. Those cities include Austin; Baltimore; Chicago; Dubuque, Iowa; Los Angeles; and Seattle, among others.

Chicago was one of the first to pioneer a green alley program in 2006. Its 1,900 miles of alleys -- “the equivalent of five Midway Airports,” according to Chicago’s complete streets director, Janet Attarian -- were experiencing periodic flooding. Mayor Richard M. Daley launched an environmental and beautification campaign that mandated that infrastructure be retrofitted, when possible, in a sustainable way. The Chicago Green Alley program’s goal was to resurface its alleys with porous material that could absorb water into the ground rather than having it spill into Lake Michigan. So far, the city has outfitted more than 100 alleys.

Nashville, Tenn., Mayor Karl Dean helps volunteers plant rain gardens in The Nations neighborhood. (Metro Photographic Services)

But Nashville doesn’t just want its project to end with the greening of The Nations’ alleys. “Our hope is that after we lay down these rain gardens,” says Creech, “the city can come in and do some additional upgrades to beautify these alleyways even more.”

In effect, Nashville wants to make its alleys more walkable and safe. It’s a new vision for an old design that is increasingly shared by other cities. Cities no longer want alleys to be simply green. They want to create “living” spaces: places that not only implement sustainable best practices, but also encourage community activities and active uses like walking and bicycling.

That’s a far cry from the role alleys play today. Alleys actually gave way to front yards in the late 19th century because they were seen as dangerous. For cities that have them, they are mostly utilitarian, home to garbage cans, parked cars, garage entrances and utility poles. But as people gravitate back to cities and as cities grow denser, additional public open spaces will be at a premium, says Daniel Toole, an architect and author of the blog Alleys of Seattle. “As cities become quite cool for everybody again, alleys and leftover spaces will be seen as essential,” he says. “They’ll be seen as the kind of place people can gather on a small scale. Communities and planning departments will start to realize the untapped potential of these spaces.”

The concept of a “living alley” comes from the Dutch word woonerf, which in English means living streets. In the Netherlands, living streets are narrow roadways shared by cars, cyclists, pedestrians and children.

It’s an idea that San Francisco has co-opted and applied to its hundreds of alleyways. Five years ago, the city helped transform Linden Alley in the Market and Octavia neighborhood from an unremarkable backstreet into a bustling “living alley” where people can hang out. Borrowing heavily from the Netherlands, planners created a 100-foot, curb-free stretch of concrete, blurring the line between sidewalk and street. The actual roadway was narrowed with granite benches and pockets of grass and lavender so that the space could be shared by cars and pedestrians alike.

Spanning 15 blocks, the Market and Octavia neighborhood is an intricate network of streets and alleys. It’s the perfect place for the city’s living alleys vision. Near downtown, it’s a sought-after location. Hundreds of new housing units have opened in the area in the past few years. “Market-Octavia is a central neighborhood that has a lot of arterial roadways that feed into freeways,” says David Winslow, an urban planner for the San Francisco Planning Department. “There’s a lot of high-volume traffic, so the idea was, ‘Hey, if we’re going to make this a livable community, why don’t we turn our eyes to making the alleys more usable to offset this high-congestion traffic environment on the main streets?’”

The Linden Alley project has been wildly successful. Surrounding residents hold block parties there and workers from nearby businesses regularly fill the area at lunchtime. The project prompted the planning department to create the Living Alleys Toolkit, which serves as a how-to guide for transforming more alleyways in the Market and Octavia neighborhood and beyond.

In addition to providing the toolkit, the planning department has held community meetings to show residents alleyways’ potential. The toolkit is based on the assumption that while there is some public money available, the bulk of the improvements would be spearheaded by community groups. “If the people who live and work along these alleys want to see them improved,” Winslow says, “they would have to organize, decide what they want and, to a certain extent, design it.” They would also have to do a lot of the fundraising. “The burden is on the community to do this,” Winslow says. “It’s not city-delivered.”

So far the planning department has guided four community groups through the process. One group has plans in hand and is actively working to get the approval and funding it needs to bring its staid alley to life. If the Linden Alley project is any guide, another alley in the Market and Octavia neighborhood could be up and running in the next five years.

San Francisco transformed Linden Alley from an unremarkable backstreet into a bustling "living alley." (San Francisco Planning Department)

But San Francisco is not the only city with “living alley” ambitions. To its south, Los Angeles’ green alley program wants to turn its blighted alleys in South L.A. into livable open spaces. Los Angeles is one of the most park-poor cities in the nation, according to the University of Southern California’s Center for Sustainable Cities. At the same time, South L.A. has the greatest percentage -- about one-third -- of the city’s alleys. In partnership with the Trust for Public Land, the city is working to add permeable pavement to its alleys to soak up rainwater, to add gardens that line the alleyways and create mini parks, and to add streetlights and crosswalks that will keep pedestrians safe. City planners hope the improvements will ultimately encourage residents to go outdoors and use the spaces for recreation.

The Los Angeles, Nashville and San Francisco projects, which range in cost from $35,000 to $240,000 per renovation, are all being paid for through one-time grants or fees rather than through an item in the budget. That’s because, says architect Toole, “city councils, transportation departments and planning departments have their hands full with lots of other projects, so making an alley a nicer place, especially if it’s already functioning, is like No. 10 on the list of things to fix in the city.”

So while cities may not be able to foot the bill for alley-improvement efforts, they still can play a crucial role as conveners. Nashville’s program, for instance, has focused on bringing together volunteers who are interested in planting rain gardens. “We haven’t seen an overall volunteer green alley project likes ours,” says Nashville’s Creech. “We looked at Austin and Chicago, but both of those were city services and didn’t have a citizen engagement component to them.”

Cities can offer a blueprint for how to get things done. San Francisco’s toolkit, Winslow points out, gives residents step-by-step instructions on how to create alleys that are “primarily for pedestrians and bicyclists as well as space for social uses.”

Local government also can work to bring state lawmakers along. “One of my next steps involves legislative recognition of shared streets as a type,” Winslow says. Unlike countries within the European Union, the U.S. has no official designation of a pedestrian priority street. And that, Winslow says, is an impediment to shared streets.

The key, say Winslow and others, is to tap into the community, determine where in a city it makes sense to partner on alley projects, and then do everything possible to coordinate and encourage those grassroots efforts. “It’s great that it is picking up,” Toole says. “It means that as more people realize the potential for these places, their government officials will be more informed and prone to help people get things running.”

Additional reporting by Kevin Tidmarsh