A planned two-month closure of Waterside Drive NW is on hold after construction crews unearthed a large utility line dating to the early 1900s during preliminary excavation.

The National Park Service said the discovery was made late last week as crews prepared for a rehabilitation project on the road, which connects Massachusetts Avenue NW to Rock Creek and Potomac Parkway. The southern section of Waterside Drive was scheduled to close Monday, Sept. 21, through Nov. 13, WUSA9 first reported.

No new start date has been set. The Park Service said crews are assessing the line before deciding how to proceed and will announce a revised timeline when one is available.

The type of utility line has not been identified publicly.

What the project involves

The Federal Highway Administration is overseeing the reconstruction of severely deteriorated pavement along Waterside Drive. The work also includes new concrete curbs and gutters, steel-backed timber guardrails and replacement lighting.

Rock Creek Park Superintendent Brian D. Joyner signed the official closure order. The NPS Record of Determination states the full closures are necessary to protect drivers and workers while heavy equipment is in use.

The project had already been pushed back once. Electronic signs originally listed a Sept. 14 start date, but NPS moved it to Sept. 21 and extended the end date, according to earlier WUSA9 reporting.

Traffic detours once work begins

Once the southern section closes, drivers will no longer be able to use Waterside Drive to reach Rock Creek Parkway southbound from Massachusetts Avenue. They will be directed to the parkway entrance at P Street NW instead. Northbound drivers on Rock Creek and Potomac Parkway will need to exit at K Street NW or at Shoreham Drive and Beach Drive NW.

A second phase was scheduled to begin Oct. 25, closing the northern portion of Waterside Drive between Massachusetts Avenue and the northbound ramp to Rock Creek Parkway. NPS said no detour is available for that connection. It is unclear whether the utility line discovery will also delay that phase.

WTOP traffic reporter Dave Dildine said Wisconsin Avenue NW, Massachusetts Avenue NW and Connecticut Avenue NW might feel more crowded, with traffic patterns shifting through the West End, Georgetown, Embassy Row and Woodley Park. "There's going to be more northbound traffic making it to the end of Rock Creek Parkway at Beach Drive, where it tends to bunch up even on a good day," Dildine said.

Access to embassies and other properties along the southern section will be maintained during construction. Most driveways along the northern section will also remain open, and sidewalks will stay accessible.

The Park Service said it notified nearby residents through fliers and other outreach. No timeline for the delay has been announced.