Here’s the math behind an academic hemorrhage: Between 500 and 600 fewer students will attend Evergreen State College next fall than in 2017, according to internal estimates. That means projected full-time enrollment is down as much as 17% from 3,500 last fall. When President George Bridges saw an internal email outlining these numbers, his impulse was to get the public-relations department to finesse them. Otherwise, he wrote, they “might end up appearing elsewhere in ways that will be used against us.”

Mr. Bridges has himself to blame. Nationwide, after administrators have capitulated to disruptive student activists, colleges have lost the support of donors, alumni, parents and prospective students. If there was one school you’d expect to defy this trend, it would be Evergreen, in Olympia, Wash. Founded in 1967, the college is proudly to the left of Berkeley and Middlebury. Its motto is literally “let it all hang out”—omnia extares—and radical activism has always been part of the pitch. But new records show that Evergreen hasn’t been spared the backlash that has plagued schools like the University of Missouri. This time, it’s coming from the left.

Evergreen’s public controversy began with the “Day of Absence” last April. In earlier years, minority students and faculty held an annual one-day walkout, but in 2017 organizers instructed all whites to stay off campus. Biology professor Bret Weinstein declined, and in an email called the decree “a show of force, and an act of oppression itself.” After the email circulated on campus, enraged students disrupted his class on May 23.

Police tried to respond, but protesters blocked them from the classroom. Later that day, Mr. Bridges ordered campus police chief Stacy Brown to accompany him to a meeting with student activists—but to leave behind her uniform and badge. Mr. Bridges stood passively as students interrupted Ms. Brown’s speech with laughter, vulgar language and boos. The next day students occupied the library, using furniture to barricade the doors.

The protests grew so aggressive that many on campus feared for their physical safety. Mr. Bridges ordered the police to stay away. “If law enforcement were to come in,” he said later, “there would be perhaps violence, perhaps damage to property, damage to students.” Ms. Brown ultimately resigned, and this week plans to file a tort claim alleging a hostile work environment. Mr. Weinstein and his wife, who also taught at Evergreen, filed a similar lawsuit last fall. The college demanded their resignation as a condition of its $500,000 settlement.