CONCRETE, Wash. — The Skagit River north of Seattle has reached its highest level in 11 years, resulting in flooding that closed roads and an alert telling some residents to prepare to evacuate.

The Skagit County Department of Emergency Management said Thursday the worst-case scenario would involve the displacement of 250 people. As of 4 p.m. only residents in the town of Hamilton had been told to prepare to evacuate.

The National Weather Service said the river at Concrete reached 36.56 feet just after 2 p.m. Thursday. That’s the highest it’s been since 2006.

Downstream, Mount Vernon work crews were preparing a downtown floodwall against potential flooding Friday afternoon.

The river was expected to begin receding on Friday but warnings were in place through Saturday.

Other rivers in Western Washington were under flood warnings including the Snohomish, Snoqualmie, Skykomish, Skokomish, Satsop, White, Nooksack, Nisqually and Cowlitz rivers.