Scott's Run Nature Preserve is open again after a six-month closure for sewer infrastructure work that Fairfax County says will keep the pipes running for another 50 years.

The Department of Public Works and Environmental Services completed Phase 1 of the Scott's Run Siphon Rehabilitation on Aug. 10, relining three deteriorating siphon pipes inside the preserve using a technique called cured-in-place pipe lining. Dranesville District Supervisor Jimmy Bierman announced the reopening Friday, Aug. 21, on X, saying the work ensures "safe, reliable sewer infrastructure for the next 50 years."

The preserve had been closed since Feb. 16. It was the third consecutive spring that hikers and trail runners lost access to the McLean woodland while the county tackled sewer upgrades, FFXnow reported when the closure began.

The siphon pipes carry wastewater from Fairfax County under the Potomac River to D.C. Water's treatment system. Without the rehabilitation, the aging infrastructure posed risks to public health and the surrounding Potomac Gorge ecosystem, which the Fairfax County Park Authority calls one of the rarest biological environments in the mid-Atlantic, according to the county's project page.

What's next

The project has a second phase. DPWES is designing work to reline siphon pipes that run under the Potomac into Carderock Recreation Area in Maryland. Construction is anticipated to begin in fall 2027, pending a National Park Service permit. The county has not said whether that phase will require another closure of Scott's Run itself.

Upcoming

• Scott's Run Nature Preserve — Open daily, sunrise to sunset, 7400 Georgetown Pike, McLean. Free admission.
• Phase 2 construction — Anticipated fall 2027 (NPS permit pending).