Gina Holbrook, 45, has been under suspicion of having an inappropriate relationship with a 17-year-old male since September 30.
Investigators say the relationship began in late 2015 and lasted about eight months.
Holbrook was a teacher in the Nevada County School District during the relationship but the male was not enrolled as a student in the district.
She is no longer employed with the district.
She has since been released on bail which was set at $75,000.