County Fire in Napa-Yolo area blamed on faulty electric fence

A wildfire burns near Lake Berryessa in Napa, Calif., Sunday, July 1, 2018. Smoke from the Yolo County fire was contributing to poor air quality in Napa, Sonoma, San Mateo and San Francisco counties, according to the National Weather Service. (Paul Kitagaki Jr./The Sacramento Bee via AP) less A wildfire burns near Lake Berryessa in Napa, Calif., Sunday, July 1, 2018. Smoke from the Yolo County fire was contributing to poor air quality in Napa, Sonoma, San Mateo and San Francisco counties, according ... more Photo: Paul Kitagaki Jr. / Associated Press Photo: Paul Kitagaki Jr. / Associated Press Image 1 of / 25 Caption Close County Fire in Napa-Yolo area blamed on faulty electric fence 1 / 25 Back to Gallery

California’s largest active wildfire, which has prompted hundreds of evacuations in Napa and Yolo counties and rekindled terrifying memories of last year’s Wine Country blazes, was caused by an improperly installed electric fence, state officials said Wednesday.

The owner of the property in the rural Yolo County community of Guinda was cited for illegally starting the County Fire, which began June 30. California Department of Forestry and Fire Protection officials did not release the property owner’s name or elaborate on what went wrong with the fence.

“It was an electric livestock fence unit. I don’t know what livestock it was for,” said Will Powers, a firefighting prevention specialist for Cal Fire.

The County Fire has charred 90,288 acres of hilly grasslands east of Lake Berryessa. The blaze was estimated to be 89 percent contained Wednesday evening. Twenty structures have been destroyed.

Like last year’s Wine Country fires, the County Fire showed explosive growth when it ignited two weeks ago, expanding to 70,000 acres within days due to strong winds, high temperatures and low humidity.

The Klamathon Fire, which has been ravaging the California-Oregon border since last Thursday, was 65 percent contained as of Wednesday evening and remained at 36,500 acres, according to Cal Fire. The number of threatened structures decreased from 1,036 to 315, officials said, while 82 structures have been destroyed and 12 damaged.

The fire has killed one unidentified Siskiyou County resident and injured three firefighters. A body was found early Friday in the community of Hornbrook, but authorities have yet to disclose the person’s gender.

Officials said a resident living southwest of the Klamath River lit a small fire last Thursday on a friend’s property that then spread, first to a tree and then into nearly hills after jumping the river.

Evacuation warnings were in place for the Copco Lake area south of the Oregon state line, and orders to evacuate remained in place for private properties west of the Jackson-Klamath county line in Oregon.

Currently, 2,767 firefighters are battling the inferno, as well as 180 engines, 24 water tenders, 25 helicopters, 77 hand crews and 32 bulldozers.

Elsewhere in California, the Hale Fire erupted Tuesday in Morgan Hill and burned 51 acres. Four horses were killed and three outbuildings were destroyed, said Pam Temmermald, a spokeswoman for Cal Fire.

The fire was 95 percent contained as of Wednesday.

Kurtis Alexander and Sarah Ravani are San Francisco Chronicle staff writers. Email: kalexander@sfchronicle.com, sravani@sfchronicle.com Twitter: @kurtisalexander @SarRavani