Firefighters remained vigilant in holding containment lines as the Chips fire grows to 18,000 acres.

Crews will continue to aggressively attack an area where the fire escaped containment lines into the Mosquito Creek drainage. Aircraft will assist throughout the day Wednesday by dropping water on hot spots near the fire's advancing edge as smoke conditions allow.

The fire is expected to slowly creep downslope towards Highway 70 on the southern flank where crews will mop-up along the line to secure additional containment. Fire activity along the western flank of the fire was minimal last night and crews will resume construction and improvement of western flank containment lines.

Containment objectives for the Chips Fire are to keep the fire south of Humbug Summit Road, north of Highway 70 and Tobin, west of the Butt Lake transmission lines, and East of Philbrook Reservoir. Crews are stationed in communities along the Feather River Canyon to provide structure protection.

Contingency lines beyond the primary containment lines are planned and the north contingency line along Humbug Road is now under construction.

The cause of the fire that began July 29, is still under investigation.