DENVER — Denver police say they have issued 28 citations for public consumption of marijuana and arrested one person accused of attempting to distribute the drug so far this weekend as revelers celebrate the traditional pot holiday of April 20.Public consumption of marijuana is still illegal in Colorado, and sales are regulated.Of the infractions police reported Sunday, 22, including the arrest, were Saturday. The remaining seven citations were recorded as of just before 2 p.m. Sunday, hours before the traditional smokeout at 4:20 p.m.Denver is just one of many cities across the country where 4/20 marijuana celebrations are planned Sunday. Elsewhere, San Francisco Police Chief Greg Suhr said his officers would be cracking down on illegal parking, camping, drug sales, underage drinking and open alcohol containers at Golden Gate Park’s Hippie Hill. Officials don’t want the unofficial pot holiday to disrupt Easter Sunday activities in the park.In Boulder, University of Colorado officials closed campus to all but students, faculty and staff on Sunday to ensure no 4/20 celebrations were held. Spokesman Ryan Huff said the tactic was working, with no arrests reported Sunday. The university says marking 4/20 is contrary to its mission of research, teaching and learning, and in the past has seeded a main lawn with fertilizer to keep revelers away.