Long-awaited Sparrow Pond wildlife restoration could begin next year

Arlington County is looking to restore and replant a man-made pond along the Washington & Old Dominion Trail starting in 2023.

Since it was built between 2001-2002, significant sediment deposits have settled in Sparrow Pond in Glencarlyn Park, harming the wildlife habitat and the water quality. About a decade ago, the county decided to defer cleaning up the sediment and instead, redesign and restore the pond, according to a staff presentation.

Fast forward to 2022 and the county is finally wrapping up the project’s planning phase and preparing for construction.

Planned work includes an access path from S. Park Drive, a residential street off Arlington Blvd that dead-ends behind Glencarlyn Park, to the pond. The county intends to dig a sediment forebay and larger pools “to better filter stormwater and restore habitat for herons, ducks, turtles, frogs and fish,” according to the project webpage.

Additional, new stormwater management facilities will redirect runoff to the Four Mile Run stream, which could cut down on pollution and clouding downstream in the Chesapeake Bay. These changes should also prevent the W&OD Trail embankment from flooding during “100-year storm events” — or storms with a 1% chance of occurring every year — such as the 2019 flood precipitated by a torrential rainstorm, according to a staff report.

Before it can start, however, the Arlington County Board needs to approve agreements with the NOVA Parks and Dominion Energy, both of which own or control parts of the land surrounding the pond, where the new access path and stormwater facilities will be located.

The Board is slated to review these contracts on Saturday.

If the project is approved, construction would begin next year and take between six and nine months.

Preparatory work is already underway with special attention to wildlife, at the insistence of community members.

In the spring of 2021, the county installed a beaver baffle to help keep water levels stable and prevent the W&OD Trail embankment from flooding, all while not disturbing a beaver encampment in the pond area.

“The beaver baffle was an elegant solution that allowed the beaver to stay without endangering the W&OD trail embankment,” the county said in a project update.”The water levels came down and the pools on the bottom of the slope dried up. The slope and trail were safer again.”

Community members have emphasized in project meetings the importance of protecting wildlife, including beavers and the pond’s namesake swallows.

“We will work together to rescue native plants and affected animals like turtles and fish before beginning construction,” the county said. “Before being released, staff will test the animals so we don’t spread disease around the County.”

Plant and animal rescues will be planned for fall 2022, according to the project page.

This project — like the ongoing dredge work at Four Mile Run to prevent extreme flooding — is part of county efforts to improve stormwater management as storms appear to intensify, which many scientists attribute to climate change.

County staff and environmental advocates have attributed some flooding, at least in part, to development — including the construction of large homes — and the associated loss of trees and other plantings that absorb water.

Fewer trees and shrubs mean more water runs into stream banks, causing erosion, water pollution and sediment build-up. That, in turn, causes more tree loss and harms to wildlife habitats, including the critters of Sparrow Pond. The county has worked to mitigate such effects through stringent stormwater requirements for new construction, though some homebuilders have complained about the cost of such measures.