Green infrastructure:
Who gets to define it?

As green infrastructure continues to gain in popularity across the United States, the term itself has come to mean different things to different people. Among U.S. cities that have developed planning documents calling for the use of green infrastructure, the term often is undefined or is defined too narrowly, according to the results of a recently published study. This lack of clarity regarding the term green infrastructure is limiting how and the extent to which the practice is being used in the United States, the authors of the study maintain.

Stormwater concepts prevail

Titled “What is green infrastructure? A study of definitions in US city planning,” the article was published January 5 on the website of the journal Frontiers in Ecology and the Environment. The authors of the article undertook the study as part of a broader investigation of “how cities conceptualized the equity of green infrastructure,” says Zbigniew Grabowski, the lead author of the article and a research fellow at the Urban Systems Lab at The New School and a postdoctoral researcher at the Cary Institute of Ecosystem Studies.

“Our guiding question was, ‘Is green infrastructure seen as a universal good by municipal agencies, or do they take into account the perceptions and experiences of diverse communities?’” Grabowski says. “As we began our plan review, we quickly realized that green infrastructure meant very different things to different types of agencies, and no one had documented this in a systematic way,” he notes. “We decided to provide some clarity and synthesis around what green infrastructure means in practice.”

For their study, the researchers reviewed 122 sustainability, climate, or comprehensive plans from 20 U.S. cities and examined their uses of the term green infrastructure. Nearly 40 percent of the plans did not define green infrastructure. Among plans that did define the term, nearly 60 percent included definitions in which “stormwater concepts [were] most prevalent,” the study notes. As for the remaining plans that included definitions, landscape concepts were most common, at 17 percent, followed by the concept of integrating green infrastructure with other built infrastructure systems, at 15 percent. Nine percent of the plans used definitions that involved other concepts.

“The most commonly considered types of [green infrastructure] included trees (90% of cities), bioretention (75% of cities), ‘other stormwater facilities’ (55%), blue-green corridors (60%), and green roofs (65%),” the article states. Although they “vary widely and significantly,” the types of green infrastructure included in the various plans “often exclude parks and larger urban green spaces in favor of smaller engineered facilities,” according to the article. 

Among the various plans analyzed in the study, the functions of green infrastructure are “primarily hydrological, although more functional diversity is provided by landscape and integrative definitions of [green infrastructure],” the article notes. 

Conflating concepts

The problem with emphasizing stormwater concepts over and above landscape or integrative concepts is that it “introduces confusion around the term green infrastructure, specifically by conflating green infrastructure with green stormwater infrastructure,” Grawbowski says. 

“Green infrastructure has its roots as a landscape planning concept seeking to connect diverse types of green spaces and amenities in order to preserve a range of ecological functions and their associated social benefits,” Grawbowski  notes. “While using ‘green’ to manage urban hydrology is important, it is one of the many functions of a robust green infrastructure system.”

As for why U.S. municipalities and similar entities tend to define green infrastructure in this limited manner, Grabowski points to the U.S. Environmental Protection Agency (EPA) and its use of the term. “The main reason appears to be that cities have adopted the language of the U.S. EPA around green infrastructure and are using this narrow view of green infrastructure as a cost-effective compliance strategy,” he says.

Confusion from the EPA

Karen Firehock, the executive director of the Green Infrastructure Center, agrees that the EPA is responsible for the change over time in the definition of the term. As coined by the Florida Greenways Commission in a 1994 report on land conservation, green infrastructure originally was intended “to reflect the notion that natural systems are important parts of our ‘infrastructure,’” Firehock says. 

For its part, the Green Infrastructure Center defines green infrastructure as comprising the “interconnected network of waterways, wetlands, woodlands, wildlife habitats, and other natural areas; greenways, parks, and other conservation lands; working farms, ranches and forests; and wilderness and other open spaces that support native species, maintain natural ecological processes, sustain air and water resources and contribute to health and quality of life,” according to the center’s website.

However, in 2006, a political appointee at EPA “who was not a scientist” began applying the term green infrastructure to best management practices that until then had been referred to as low-impact development (LID), Firehock says. Such practices, including bioswales and green roofs, are designed to maintain as closely as possible the predevelopment hydrologic regime on developed lands.

The change in terminology “led to confusion,” Firehock says. “We wrote to the U.S. EPA, as did staff from [EPA] Region III, asking [EPA headquarters] to stop confusing the term and go back to calling these structures LID,” she says. “They did not, and now some folks are confused.”

A new definition

In their article, the researchers offer what they call their own “synthetic” definition of the term. “Green infrastructure (GI) refers to a system of interconnected ecosystems, ecological-technological hybrids, and built infrastructures providing contextual social, environmental, and technological functions,” the authors state. “As a planning concept, GI brings attention to how diverse types of urban ecosystems and built infrastructures function in relation to one another to meet socially negotiated goals.”

“Our definition goes beyond existing definitions by synthesizing how the term is actually being used by city planners,” Grabowski says. “Instead of just focusing on the landscape conservation idea, or the green stormwater concept, we integrate a range of thinking that wants to simultaneously preserve, enhance, and restore ecological systems and functions in cities while making a number of built infrastructure systems more sustainable and ecologically friendly—like stormwater, but also transportation, energy systems, material handling, and building materials. We hoped to lay a conceptual foundation for a diverse range of greening efforts that can be planned in relation to one another to maximize impact and minimize costs.”

Absent a shift to a broader conception of green infrastructure, some participants may need to speak up, the authors contend. “Given current dominance of hydrologic concepts, GI planning and research may require an intervention from ecologists and landscape planners,” the article states.

What might such an intervention look like? “There are many opportunities to bring about a focus on ecological connectivity in urban planning,” Grabowski says. “ A big one is to highlight the beneficial role that interconnected green and blue networks play in providing many services in cities.”

That said, the critical role that governmental regulations play in the planning process must be acknowledged, Grabowski notes. “We need to think seriously about what types of policy mechanisms we can put in place for cities and regions to require to protect their overall ecological integrity and functionality,” he says.

“Even developers would likely be on board with a regulatory framework that had strict protections for ecological networks if it was clear what types of development was permissible in other areas, especially if that development integrated site-scale GI practices,” Grabowski says. “In other words, we need to think and enact GI policy that functions across scales and sectors in order to create built environments that integrate harmoniously with their ecologies, much like the original proponents of the GI idea wanted.”

Besides Grabowski, the other authors of the article were Timon McPhearson, a professor of urban ecology and the director of the Urban Systems Lab at the New School and a senior research fellow at the Cary Institute of Ecosystem Studies and the Stockholm Resilience Centre at Stockholm University; Marissa Matsler, an Oak Ridge Institute for Science and Education postdoctoral fellow at the U.S. EPA; Peter Groffman, a professor at the Environmental Sciences Initiative within the City University of New York; and Steward Pickett, a plant ecologist at the Cary Institute of Ecosystem Studies.

—OWN