Nathan Brostrom, executive vice president of business operations for the University of California, said the system was now in the middle of the worst financial crisis since the Great Depression. In the last year, the state has cut $750 million from the system’s budget. This year, for the first time, the system receives more money from tuition than from state aid — but that only makes up for roughly a quarter of the cuts from the state. Over all, the budget is the same as it was in 1997, when there were 75,000 fewer students enrolled.

In recent years, many campuses have made a more concerted effort to recruit out-of-state students, who pay more in tuition. But some have criticized the practice, and last month one state lawmaker introduced legislation to cap the number of out-of-state students.

Part of the problem, officials say, is that the amount of money provided by the state has been unpredictable, making long-term planning difficult.

“If we don’t get some kind of change this year, we are going to have an immediate unfathomable situation that really has the potential to completely change the university,” Mr. Brostrom said.

The University of California system is made up of 10 campuses, including Berkeley and U.C.L.A., both ranked by U.S. News in the top 25 of all national universities, public or private. The California State University system, with lower tuition and easier admission requirements, is even larger, with 23 campuses and roughly 425,000 students.

Now, all but seven of the Cal State campuses are considered “impacted,” which means they have stricter admission criteria for applicants applying from outside the immediate area. Five years ago, only five campuses held such a distinction. Many students who attend Cal State campuses live at home to save money, which often means that if they are unable to attend a campus within driving distance they will not enroll.

The financial picture will grow even more dire if the tax increase backed by Governor Brown does not pass in November. The president of the University of California and the chancellor of California State University are both urging voters to approve the increase, saying that any more cuts would mean irreparable harm.