Pro-pot protesters at the University of Colorado were forced to disperse on Friday, CNN reports.
Hundreds of people turned out for the event, but no one smoked at the rally, CNN reports.
According to CNN, the school closed the campus to outsiders and spread an unpleasant-smelling, fish-based fertilizer on the quad before enclosing it in yellow police tape and stationing police officers around the perimeter.
Three people were arrested for trespassing when they walked onto the quad, sat down and refused to leave, USA TODAY reports.
"Clearly they wanted to get arrested," campus police spokesman Ryan Huff said.
In past years the Norlin Quad on the campus of the University of Colorado at Boulder had drawn 10,000 to 12,000 people for the event that occurs on April 20, CNN reports.
According to USA TODAY, Huff estimated that the university would spend about $110,000 on law-enforcement Friday, about double the amount spent last year.