The California State University faculty union will bring teaching to a halt at all 23 campuses in April — an unprecedented move for the 470,000-student university system — unless an agreement over salaries is reached before then, it announced Monday morning.

The strike would be held for five days: April 13-15 and April 18-19.

“We don’t want to strike, but we will,” said Jennifer Eagan, president of the California Faculty Association and a professor at CSU East Bay. “The faculty will not back down.”

Citing the state’s economic recovery and the additional funding flowing to the massive university system, the union is demanding 5 percent raises for its members and an additional 1.2 percent for some faculty, a proposal that would cost nearly $102 million, according to CSU. The 5 percent raises alone would cost $82 million.

The union argues CSU can afford it, and that it must make faculty pay a priority. The average salary of its members, including part-time employees, is about $46,000, the union reports.

Faculty members tightened their belts during the Great Recession “in the hopes that when the good times came, we’d be able to negotiate a good contract,” Eagan said. “Then the good times came, and we’re still not able to negotiate a good contract.”

The CSU administration — which has offered the union a 2-percent raise — has said it needs to balance faculty pay with other needs, including access to courses, facility upgrades, the hiring of new faculty and student-support services.

The faculty union rejected the 2 percent raise and in October voted to authorize a strike. Before the union can legally strike, however, it must wait for a report from a neutral arbitrator, expected in mid- to late March.

The April dates were announced this week, Eagan said, to help faculty prepare.

Faculty at CSU East Bay and CSU Dominguez Hills, held a one-day strike in 2011, but have never held a strike across the system.

“This is a historic strike, if it happens,” Eagan said.

Follow Katy Murphy at Twitter.com/katymurphy.