After months of meticulous restoration work, Arlington joggers, hikers and dog walkers can again enjoy the natural beauty of Donaldson Run stream.
The county has completed its first ever comprehensive stream revitalization project at Donaldson Run in Zachary Taylor Park, in an effort to reduce stream bank erosion, improve the water quality and protect underground sewer lines.
The $1.4 million program restored a 3,000-foot section of the stream near Military Road, and enhanced the surrounding trail infrastructure.
Due to the large degree of development in the adjacent neighborhoods, the stream received a high volume of runoff during storms. The excess water led to severe erosion of the banks of Donaldson Run, causing sediment to flow into the Potomac River.
"We were losing maybe 100 tons of dirt a year that was flowing into the Potomac," said Larry Finch, a member of the Donaldson Run Civic Association who helped orchestrate the project.
THE EROSION became so acute that it widened the channel, undercutting soil beneath trees and causing them to fall into the stream. Numerous parts of the stream banks become too treacherous for residents to walk through.
The sewer line beneath the stream became exposed and occasionally was breached, contaminating the floodplain, Finch said.
Past restoration efforts included placing stone walls, called rip rap, along the side of the stream. But those measures only increased erosion, by narrowing the stream and shifting the water’s energy to new locations, said Aileen Winquist, an environmental planner for the county.
In 2001 the Donaldson Run Civic Association asked for Neighborhood Conservation funding to study permanent restoration possibilities and for the county to replace pedestrian bridges and replant lost trees.
Thanks to funding from the Watershed Management Fund, the conservation program and state grants, work began in earnest last August.
The new stream is now several feet higher, and the sanitary line has been reburied. The revitalization process also focused on altering the pattern of the stream, and slowing it down, to stop soil erosion.
"We used a method called natural stream channel design," Winquist said. "When doing a project like this with the stream out of balance, you try to find ways to get it stabilized."
The stream was molded into a more meandering and curving pattern to help better channel its energy, and u-shaped step pools were created for the water to spill out onto.
While the county had to remove nearly 100 trees as part of the restoration project, it planted more than 400 new trees and 600 shrubs along the stream’s banks.
"The new forest should be healthy and stable for a long time because there won’t be erosion," Winquist said.
County Board Chairman Chris Zimmerman lauded the restoration project during a ribbon-cutting ceremony on April 29, and said the process created a more environmentally friendly and safer stream.
"This creates a better environment for those of us here who enjoy it, but it also impacts the regional environment," Zimmerman said.