The county fire department says a person either accidentally or intentionally started a one-acre wildfire near Alpine Lake, in Marin Municipal Water District land, last Friday. An investigation has ruled out all other causes for the fire, which was first spotted by a driver on Fairfax-Bolinas Road who reported seeing smoke and flames at around 9 p.m. The area was so dense with vegetation that California Highway Patrol offered a helicopter to pin down the exact location of the blaze—just northwest of the road, between two prominent fingers of the lake. Firefighters used bulldozers and chainsaws to get to the conflagration, and fully contained it by 5 p.m. on Saturday. Though it began during cooler, more humid hours, drought conditions contributed to the fire, said Mike Giannini, Marin County Fire Department’s battalion chief. “That’s where we are right now. We have no moisture in most of this vegetation,” he said. The department recently brought back seasonal firefighters not typically employed in the rainy season because of the drought.