Richard Alexander Vives, 42, of Santa Rosa, is charged with seven felony counts alleging oral copulation, penetration with a foreign object and sexual battery while the victim was intoxicated.
Vives also is charged with a misdemeanor count of contributing to the delinquency of a minor.
Vives is out of custody under supervision by the county probation department and Judge Julie M. Conger prohibited anyone under age 18 except his children from being in his home when he is present.
Conger set Vives' preliminary hearing date for Dec. 1.
Defense attorney Kristine Burk said the alleged victim is not connected to the school, the soccer team or Vives' coaching duties. She said the alleged victim is a friend of Vives' daughter and the offenses allegedly occurred in Vives' home.
Burk said, "The degree of intoxication of the various parties will be in dispute.
"The most serious charge is she was unable to resist, which is akin to rape. There was no sexual intercourse. It was equivalent to foreplay," Burk said.
"He is very focused right now on taking care of his family," Burk said. "He is a well-respected member of the community who is going through a hard time."
Piner High School Principal Mary Beth Halsey said Vives was a walk-on coach who was not employed in any other capacity at the school. She said he was cleared to coach by the Santa Rosa City Schools district.
This was Vives' first year coaching and he began in September, Halsey said. He was coaching the junior varsity girls' team, which includes students in grades 9-12, Halsey said.
District Superintendent Sharon Liddell said all prospective hires go through a screening process. She said walk-on coaches can be volunteers or hired, as Vives was, and they receive a stipend at the end of the sport's season or a salary.