Air tankers battled a 231-acre blaze off O'Byrnes Ferry Road near Tulloch Reservoir yesterday afternoon. No homes were threatened by the flames, which were reported about 3:30 p.m. The cause of the fire is under investigation. Damage was estimated at $40,000. The fire was 100 percent contained at 7:30 p.m. Six engines from California Department of Forestry and Fire Protection, two water tenders and six inmate crews will continue mopping up today. Fire officials expect the blaze to be out by 6 p.m. Firefighters from CDF, Sierra Conservation Camp, Jamestown Fire Protection District, the U.S. Forest Service and numerous other area departments responded. Tuolumne County Fire Marshal Kary Hubbard said Tulloch boaters got too close to a helicopter as it scooped water from the reservoir.