Firefighters battling the Walker Fire near Idaho City kept flames from creeping closer to Idaho 21 and homes on the southern flank of the fire Monday, while it burned deeper into heavy timber on the northwestern side.
The fire has burned an estimated 4,589 acres, up from the 2,500 acres reported Monday morning.
Air quality in the Treasure Valley, where smoke from the fire drifted, was in the moderate (yellow) range early Tuesday in parts of Meridian and Nampa. Conditions in Boise was in the good (green) range. On Monday, smoke was heavy throughout the valley and the air quality was listed as unhealthy (red).
When air is in the moderate range, air quality is acceptable but people who are unusually sensitive to ozone may experience respiratory symptoms, according to the Idaho Department of Environmental Quality.
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Containment lines are holding on the southwest corner of the fire near the Clear Creek subdivision and crews have begun mopping up hot spots there. The blaze is about 35 percent contained as of Wednesday morning, managers reported.
The northwest flank saw the most significant growth Monday, with flames spreading toward Rattlesnake Creek and into Wild Horse Creek. Smoke from the burning in timber brought columns of smoke visible from miles away.
On Tuesday, five helicopters will be used to drop water onto flames burning in the northwest corner while more than 200 firefighters continue efforts to hold containment lines along the fire’s western, southern and eastern perimeters. Those areas are where homes and other structures are most at risk. Additional crews will work on the northeast corner of the fire.
Evacuations and closures of roads and portions of the Boise National Forest remain in effect. Fire managers scheduled a community meeting at 7 p.m. Tuesday at the Idaho City Community Center, 100 Main St.
The fire started Saturday afternoon about eight miles southwest of Idaho City in Boise County. The cause is still under investigation, but fire officials said there were no lighting strikes in the area and the fire was likely man-caused.
The Idaho Department of Lands oversaw firefighting efforts before being relieved Tuesday morning by the Great Basin Incident Management Team 6.