Arlington County has seen the fruits of its labor in the five years since the restoration of a Donaldson Run tributary at the Zachary Taylor Nature Area.

The $1.5 million project — initiated, in part, thanks to the local civic association — has allowed the rebuilt portion of the stream to withstand erosion from severe storms and to become home to the highest-quality water in Arlington County.

And the restoration of a second Donaldson Run tributary could begin as early as next year.

Such projects help the county improve its overall water quality and realize its commitments to reduce pollution and runoff, officials said.

"Stream restoration is a long-term method to reach all those goals," said Jen McDonnell, an Arlington County stormwater outreach specialist.

"It takes some time to get established, but it's addressing nutrients, it's addressing sediment, it's addressing the volume of water and the velocity of the water, it's connected to the floodplain again… So, it's helping the county try to work toward meeting our goals with regard to the Chesapeake Bay restoration."

The problem occurred over the long term, too.

Donaldson Run Tributary A, as it's called, suffered severe erosion over the past 30 years. What the county has seen with its urban streams is downward erosion — banks become steep, which diminishes a gradual floodplain and can cause trees to weaken and fall.

At one point, a sewer line that originally had been buried 3 feet underground was exposed and leaked raw sewage into the water.

In 2001, Arlington County completed a watershed management plan. One of its recommendations was stream restoration.

Around that time, the Donaldson Run Civic Association began expressing concerns about the stream to the county. The civic association applied for and received a $25,000 neighborhood conservation grant from the county — money such associations often use for sidewalk construction or traffic calming — to study the stream.

The request was "a little bit unusual" but showed the stream was "very valued by the neighborhood and the folks who live around there," said Aileen Winquist, watershed outreach program manager.

The public involvement and design phases took several years, but actual construction took about six months.

This involved filling some of the lost floodplain, adding stone steps that would slow the water as it flowed and allow it to pool, and engineering curves to reduce the overall speed.

Healthy streams have high numbers of small organisms that live in the water. The restored half-mile section of Donaldson Run Tributary A has the highest numbers in Arlington County, McDonnell said.

"That's a definite sign that with time and as that restored area continues to grow and mature we are seeing positive results," she said.

Design work is almost complete on Tributary B. The county hopes to begin construction on that next year, Winquist said.

"Before we had even done the first project, at one of the civic association meetings, people were asking, 'When are you going to do this other branch?' " she said.

The county is also in the preliminary stages of restoring a small part of Windy Run and in the midst of a long-term project for the lower section of Four Mile Run. The latter involves working with the city of Alexandria and the U.S. Army Corps of Engineers.

Arlington's stream restoration efforts were one of the examples given as to why this county served as a backdrop last month for the award of more than $9.2 million in grants to nonprofits and local governments from New York to West Virginia as part of a larger effort to help improve the condition of the Chesapeake Bay watershed.