As the University of Colorado tries to figure out how to divorce itself from the 4/20 pot-smoking picnic that takes place annually on its campus, one thing is for certain, officials say: The problem can't be dumped on the city of Boulder.

For the past few years, town-gown relations have been strengthening as the city and CU have collaborated on issues ranging from alcohol abuse among college students to appropriate building heights for campus structures. But barring pot smokers from campus -- and displacing them into the city's jurisdiction -- would put a strain on the city and CU's budding relationship.

CU's student government voted almost two weeks ago to move the 4/20 smoke-out off the campus.

"The answer is we don't know where it goes," said CU spokesman Bronson Hilliard. "We're not recommending a strategy on where it should go. Nobody wants to displace it on the city of Boulder. It's not something we want to unload on somebody else. That makes the solution more of a challenge."

The unofficial 4/20 gathering on Norlin Quad has surpassed 10,000 people, making it the largest smoke-out on a college campus. A few years ago, demonstrators staged a smaller, secondary smoke-out at the Central Park Bandshell -- but since then they've joined the masses at CU.

Hilliard said the university is in constant communication with the city about its plans for ending 4/20.

Boulder City Councilman Ken Wilson -- who lives on University Hill, a neighborhood densely populated with students -- said he is unsure where the 4/20 revelers would go should CU put an end to the unofficial event.

"I'm sure the idea is not to dump it on the city," he said. "How you manage to avoid that is a good question. There really isn't a place in the city where people could go -- other than Pearl Street or city park. We tend to be stricter about enforcing marijuana laws than CU is, though."

Wilson said that demonstrations are an important part of democracy, until they become a public safety issue, as is the case of the 4/20 smoke-out.

Frank Bruno -- who served as city manager before taking a vice chancellor job at CU -- said that the university is gaining momentum toward ending the event. Bruno left his job at CU last summer to become vice president of administration for Boulder-based Western Disposal, Inc.

"Having the students on board is huge in my estimate," he said. "We hadn't had that in years past."

Bruno said that his former colleagues at CU are mindful about the city's concerns surrounding 4/20, and together they need to show that the smoke-out is not a productive event for the community.

Other universities across the country are also faced with managing large 4/20 events, and in some cases, the school and the local town have worked together. The University of Michigan and the City of Ann Arbor have collaborated to manage crowds at "Hash Bash" -- a pro-marijuana demonstration that is in its 40th year and is staged on campus every April. The event, in peak years, has drawn about 1,600 people.

Rick Fitzgerald, a spokesman for the university, said the school steadfastly supports free speech on campus. But police ticket those who smoke marijuana during the Hash Bash.

"It's not a free pass kind of day," he said. "In recent years, it hasn't been a major disruption to the community. There are no discussions -- that I'm aware of -- of people trying to take steps to end it."

Contact Camera Staff Writer Brittany Anas at 303-473-1132 or anasb@dailycamera.com.