Spokeswoman Farrah Emami says 18-year-old Christopher Michael Casey pleaded guilty Thursday to a court offer of one misdemeanor count of reporting a false bomb threat.
Prosecutors had charged Casey with a felony and objected to the sentence and charge reduction.
Casey left a note on his teacher's desk at noon on Dec. 14, threatening that a bomb was hidden on the campus and set to detonate.
Police responded and didn't find bombs at the school. An investigation led to Casey.
Casey was also sentenced to six years' probation and must stay at least 200 yards from the school.