Work to reduce fuels that could feed the Middle Fork Fire will close the North Entrance to Crater Lake National Park in Oregon on Tuesday.

The closure, to allow firefighters on the Middle Fork Fire to prepare control lines along the entrance road, is expected to last a week. Fire crews will reduce fuels along the north-south route creating a defensible zone to keep the Middle Fork Fire from threatening park infrastructure and progressing further east, a park release said.

The North Entrance Road will be closed from North Junction to the park boundary at the junction with Highway 138. This closure is necessary to ensure the safety of fire crews and the public. All other park roads will remain open, except for construction closures on East Rim Drive.

Crater Lake National Park remains open and is accessible from Highway 62 on the western and southern routes. Expect longer lines to access the park due to all traffic coming through one entrance station.

The fire, which was reported July 17, is located in the northwest corner of the park and approaching 5,000 acres in size with zero percent containment, according to Monday morning's fire report. There were 31 firefighters fighting the flames.

"Fuels largely consist of heavy dead logs from previous fires with a mix of standing and down material. Some light grasses and brush are also found in the fire area," the report noted.

Smoke reportedly has been a problem in the national park. Trails closed due to the fire include Bald Crater Loop, Boundary Springs Trail, portions of the Pacific Crest Trail, and Lightning Springs Trail.