A 19-year-old Waipahu man has pleaded not guilty to charges that he kidnapped and sexually assaulted a 15-year-old girl over several months.

Travis Taaga, of Kipou Street, was charged with three counts of first-degree sexual assault, three counts of kidnapping and one count of third-degree assault. He remained in custody unable to post $200,000 bail.

Taaga took the girl to the beach and other areas to sexually assault her in his truck, a source familiar with the investigation said. He coerced the girl into not reporting the incidents, the source said.

Taaga was arrested Saturday night, pleaded not guilty on Monday and is scheduled for a preliminary hearing Wednesday.