The 20-year-old woman who was killed in an early morning car crash on the Nipomo Mesa on March 11 was under the influence of alcohol at the time of the fatal crash, the CHP said Friday.
Toxicology reports also determined the presence of marijuana in her system.
Officers said that Alicia Renee Carreras of Arroyo Grande was driving north along Stanton Road south of Lyn Road, about a half-mile south of Los Berros Road, about 3 a.m.
She apparently veered off the west edge of the roadway and hit a large tree, according to CHP.
No one spotted the crash until a driver passed by nearly two and a half hours later.