Police say 19-year-old Cameron S. Ehrlich, who lives on campus, was booked into Whatcom County Jail for riot, failure to disperse and interfering with a street sign.
Three non-students were arrested earlier in the week. Police squad cars were damaged, street signs were knocked down and people threw beer cans and other items at officers during a large party that turned into a riot Saturday.
Police Detective Gina Crosswhite says two others have been identified but have not been located. The department has posted photos of 11 people involved in the melee on its website and is asking the public to help identify them.
Western Washington University President Bruce Shepard said the school works hard to avoid a party atmosphere, making sure prospective students know the campus has no fraternities and is focused more on community service than partying.
"I really believe the vast majority of our students are actually disgusted by this," he said.
University crime statistics show 19 students were arrested in 2012 for liquor law violations, and nine were arrested last year for drug-related violations. Those numbers are down considerably from 2010 and 2011, when there were 96 and 66 liquor law violation arrests respectively, and 19 and 40 drug-related violations.
University spokesman Paul Cocke said expulsions and suspensions for breaking the university's drug and alcohol policies are rare because few students are found to be repeat offenders.