Feature Article - November 2019
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A Path Toward Conservation

The Environmental Benefits of Trails & Greenways

By Chris Gelbach

While the economic and transportation benefits of trails and greenways are well-established, the ecological benefits can be great too. Making the most of these opportunities requires a focus on a wide range of environmental topics during trail planning, construction and ongoing maintenance.

Greenways Defined

To understand both the positive and negative environmental impacts of trails and greenways, it's important to understand the distinction between the two. "A greenway to me is really the corridor of land," said Chuck Flink, a landscape architect and president of Greenways Inc., a greenway and open space consulting firm based in Durham, N.C. "The corridor could be pretty wide or pretty skinny. It's the land and, in some cases, the water. The trail is the tread—the pathway that we use."

According to Flink, separating the two provides the opportunity to talk about the environmental impact of the pathway or tread. "To me, there's no negative impact of a greenway on the environment because the greenway is the environment," Flink said.

The environmental impact of the trail itself needs to be considered throughout the process. "On occasion, there are sensitive landscapes that need to go through environmental assessments," said Liz Thorstensen, vice president of trail development for the Rails-to-Trails Conservancy. "But I would say that on the whole, for the rail-trail movement and the rail-width trail movement, oftentimes those projects are cleaning up almost blighted space."

Trail Planning

That said, Flink sees some projects go to extraordinary lengths to disturb environmentally sensitive areas as little as possible. He noted the example of the Violet Crown Trail which runs through Austin, Texas, and that will ultimately be a 30-mile trail through Central Texas. During planning for that project, a team from the Ladybird Johnson Wildflower Center walked abreast along the proposed pathway to make sure the route didn't disrupt any environmentally sensitive areas.

In some areas, the trail itself may not be an issue, but the construction can be disruptive to local habitats. Flink noted the example of California condor nests in the wall of the South Rim of the Grand Canyon that prevented construction on the Grand Canyon Greenway trail during that nesting season.

According to Jeffrey Ciabotti, Mid-Atlantic deputy planning director and trails practice lead for Toole Design, a leading multimodal transportation design and planning firm, trail considerations in environmentally sensitive areas can also include things like lighting. "You want to make sure that you've got darkened areas for nocturnal animals and specialized lighting that orients down so you're not creating light pollution that disturbs local habitats," Ciabotti said.

Other considerations include designing trails in areas with sensitive vegetation to include barriers that protect the underbrush and discourage trail users from wandering off the path. "Making sure you understand that area of development is really the most important factor to consider when you're putting in a project like this," Ciabotti said. "Making sure that you're creating a buffer zone between the trail and the essential parts of the vulnerable area is one of the first things you should be looking at."

Carefully designed trail corridors can not only conserve existing habitats, but also improve them. Thorstensen mentioned the example of considering the loss of pollinators across the country and planting vegetation along the trail corridor that encourages pollinators.

One example of a greenway that goes far beyond this effort is the Prairie Corridor in the Lincoln, Neb., region. The project is both a tallgrass prairie restoration project that has preserved more than 5,000 acres of land so far for new prairie habitat, and the home of what will be a 14.5-mile trail that will connect to a larger 134-mile regional trail when complete.

Design elements like underpasses for small mammals and elevated boardwalks to preserve wetlands can also help alleviate habitat depletion. But the fact is that the land conservation and habitat preservation provided by trails can also be a boon for edge species such as deer, raccoons and rabbits. In fact, Flink noted that when Grand Forks, N.D., proposed a greenway for flood mitigation and recreation after a flood in 1997, it also planned for potential overpopulation of some of these species.

"A big concern they had was that edge species wildlife would take over if they didn't manage it," Flink said. "They actually have an edge species wildlife plan and work with those species of wildlife."

A Connection to Water

In that greenway and others, a growing understanding of the increasing threat of flooding is spurring attempts to combat it in communities nationwide through sustainable design—and greenways and trails are often part of the equation.

A prototypical example is the Lafitte Greenway in New Orleans, which was proposed after Hurricane Katrina. Its design includes elements to store and retain stormwater, decrease flooding, mitigate urban runoff to improve water quality, increase trees and vegetation, and build habitat for beneficial fish, amphibians and birds. "It's a good example of how a community learns from a disaster, and how a trail can be part of the solution through thoughtful design and green infrastructure," Ciabotti said.

Another example is a project in the planning stages that Ciabotti is involved with now in Virginia Beach, Va., that will convert an often-flooded golf course in the middle of the city into stormwater mitigation with a loop trail around it. "I think we're going to see more and more projects like that as water becomes an issue throughout the country."

At the same time, situating trails along river pathways remains a common, enduring and appealing approach. The Anacostia RiverWalk Trail, for instance, offers roughly 16 miles of separated, multiuse trails along or connecting to the Anacostia River in D.C. and Maryland, with eventual plans for the trail to extend roughly 25 miles.

Over time, efforts to improve water quality in the river have included restoring five streams that flow into the Anacostia, along with investment in a $2.7 billion sewer tunnel system and greening program. These and other efforts have helped turn the once heavily polluted river into one that is close to being fully fishable and swimmable, with improved water quality, wildlife repopulation and more accessible shorelines.