Smoke from Mosquito Fire continues to blanket Lake Tahoe

Residents and visitors to Lake Tahoe and its surrounding areas remained under a cloud of smoke early Monday, as firefighters kept the Mosquito Fire in Placer and El Dorado counties from spreading.

Air-quality index readings early Monday showed very unhealthy figures in most places, a slight uptick from Sunday when the air quality was hazardous. The worst figure Monday came at 10 a.m. in Foresthill, where IQ Air, an air-quality measuring company, measured the AQI at 820 (hazardous). The fire is burning about 5 miles from Foresthill, according to fire officials.

AirNow, which uses the official U.S. Air Quality Index (AQI), had 11 a.m. readings of 407 (hazardous) in Auburn; 223 (very unhealthy) in Colfax and 162 (unhealthy) in South Lake Tahoe.

A small pocket of moderately healthy air was in the Truckee area; the AirNow AQI was 70 at 11 a.m.

The Mosquito Fire itself did not gain in size early Monday; Cal Fire said firefighters kept it from expanding overnight.

The fire had charred 46,587 acres, 73 square miles, by Monday morning at 8 a.m., Cal Fire said in its morning update. The fire also remained just 10% contained, the same percentage as Sunday evening.

The blaze is the second-largest in California this year. The McKinney Fire in Siskiyou County burned 60,138 acres.

The Placer County Sheriff’s Office said 11,260 people have been evacuated, including approximately 5,900 in Placer County. Approximately 5,848 structures are threatened.

According to Cal Fire’s summary early Monday, the blaze is progressing primarily to the north and east. The fire accelerated earlier Sunday in the drainage between Foresthill Road and Deadwood Road, and crews were working to build containment lines to stay ahead of the fire in that area.

Cal Fire also said that a “smoke inversion laying over the fire area” was expected to last through Monday morning and that southwest winds could start clearing some of the smoke by early afternoon.

The Mosquito Fire is one of three currently burning in the state that have burned more than 10,000 acres. According to Cal Fire’s 10:30 a.m. updates, the Fairview Fire has burned 28,307 acres in Riverside County and was 53% contained. The Mountain Fire in Siskiyou County had burned 13,254 acres and was 60% contained.