Problems with excessive partying have persisted for decades on this roughly half-square mile that is home to 23,000 people, but the violence has brought out politicians, university officials, police and student leaders to call for more prudent partying.
The daytime bash known as "Deltopia" isn't sanctioned by the university or formally planned, but it's a well-known happening the first weekend of spring quarter in the community next to UC Santa Barbara's campus and picturesque beachside cliffs.
It evolved from "Floatopia," a beach party banned since 2009 after it was deemed an environmental and safety hazard because of trash, human waste and near drownings. Since then, beaches are closed that weekend, and the party migrated a block inland to Del Playa Drive.
Authorities ramped up patrols after a Cal Poly San Luis Obispo student fell to her death off the cliffs last year and an overcrowded balcony collapsed, injuring several partygoers.
With social media spreading the word, the party has grown. As many as 25,000 people packed the sunny streets last Saturday in classic Isla Vista garb — bikinis, flip-flops, tank tops and shorts. With drinks in hand, they lined yards in front of two-story apartment buildings and crowded overhanging balconies.
Violence broke out around 9:30 p.m., after a university officer trying to break up a fight was hit in the head with a backpack filled with booze bottles. Hundreds of people threw rocks, bricks and bottles at officers, tore down stop signs, rocked cars and smashed windows. Authorities rolled out armored vehicles, lobbed tear gas and fired rubber bullets and foam projectiles to disperse surging crowds.
State Sen. Hannah-Beth Jackson called it "spring fever on steroids." She said officials need to look at Isla Vista's overcrowding, its isolation from services and the permissive culture of binge drinking. Those factors have been exacerbated by the area's party-hard reputation.
"Students historically get together and party," Jackson said. "But it's not as extreme as what we saw on Saturday."
And a 17-year-old from Los Angeles, accused of starting the incident by wielding the bottle-filled backpack, has been charged with mayhem, resisting an officer and assault on a police officer. He was charged as an adult.
Much of the violence was blamed on visitors. Of 62 people cited or arrested who claimed to be students, only 16 said they were from UC Santa Barbara, according to preliminary data provided by Santa Barbara Sheriff's Office.
Still, UC Santa Barbara Associated Students President Jonathan Abboud said it was up to students to take responsibility.
After getting tear-gassed trying to calm the crowd, Abboud posted on Facebook that "what happened last night in Isla Vista was inevitable and we are in part to blame for it because we encouraged this culture."
The post generated more than 1,600 likes and 80 shares and seemed to speak to a new reality. Isla Vista is not only the locale for partying but has, over the last year, brought violence: multiple sexual assaults and stabbings, including one Saturday evening before the riot.
Some students criticized police for a heavy-handed approach and lack of communication. Students had just returned from spring break last week to find surveillance cameras among the palms towering over Del Playa Drive featuring large warning signs that they were being watched.
An Isla Vista Foot Patrol sergeant posted on Deltopia's Facebook page that no music would be allowed during the party and violators could be arrested.