A 27-year-old woman on a personal watercraft suffered head injuries Sunday at Lake Sonoma when she and another on a similar craft collided, emergency officials said.
The crash was reported at 4:24 p.m. near a boat ramp on the lake, dispatchers said.
The woman was at some point unconscious and tended to by paramedics with Geyserville Fire and Bell's Ambulance until a helicopter could get to the remote area, according to dispatch reports.
Several area helicopters were out of service or otherwise engaged and a CALSTAR helicopter from Mendocino County was called to the scene.
The helicopter unit lifted off from Lake Sonoma at 5:10 p.m. and flew the woman to Santa Rosa Memorial Hospital.
No more details were immediately available.