PORTLAND, Ore. (KOIN) — The battle against the S-503 Fire on the Warm Springs Reservation continues Wednesday.

Aerial infrared technology has given officials a more accurate estimate of acreage burning, which is now reported to be 6,556 acres or just over 10 square miles. As of 9 p.m. Tuesday it was 20% contained.

The S-503 Fire is about 2 miles east of Hwy 26 and 7 miles northeast of Simnasho. The hot, dry conditions and relatively low humidity have been a factor in fighting this fire — but officials say Tuesday’s cooler weather allowed firefighters to make significant progress. 

With over 300 firefighters, crews were able to successfully establish a containment line around the entire fire perimeter, but they are still working to secure it. Firefighters have been patrolling for hot spots and spot fires as more resources continue to arrive. They currently have multiple air resources on the scene.

They will continue their aggressive work to strengthen the lines on Wednesday. Officials say their biggest concern is the possibility of thunderstorms heading west, which could cause gusty and erratic winds.

A burn ban on the Warm Springs Reservation is in effect “until further notice,” according to the U.S. Environmental Protection Agency, and applies to all outdoor and agricultural burning with the exception of ceremonial and traditional fires. The federal agency is also asking reservation residents to reduce other forms of air pollution, including driving and idling vehicles.

Evacuation Levels as of 9 p.m. Tuesday

  • Level 2 GET READY: All residences west of the intersection of Kelly Springs Road and Back Walters Road, anything else previously under level 1 east of Kelly Springs to Reservation Rd including Walters Corners and the community of Pine Grove.

As of Monday afternoon, there were about 250 homes and structures in the Pine Grove area under Level 2 evacuation notices.

The fire first sparked last Friday. It’s not clear what caused this fire to start, officials said. The fire is about 92 miles from Portland.