State mediators are getting involved in negotiations between Mt. Diablo Unified School District and its teachers’ union, which this week filed an impasse declaration, saying the district’s bargaining team has failed to present a reasonable proposal.

The current contract for workers with the Mt. Diablo Education Association, which represents more than 1,500 teachers, nurses, librarians and various school specialists, expired on June 30, and MDEA filed the declaration with the state’s Public Employee Relations Board after negotiations left the two sides far apart.

PERB is now referring the case to a mediator who will schedule meetings in an attempt to reach an agreement.

According to the district, agreements have yet to be reached on salaries, benefits, class sizes and other topics. The union is asking for a 12.5 percent salary increase over the three-year proposed contract, saying its members have not had a salary increase since 2017, while the district says its most recent offer was a 7 percent raise over the three years.

“If district management agrees to a fair and just settlement, we can reach a tentative agreement during mediation. If district management continues to fail our educators, the next step after mediation is fact-finding. If the fact-finding process does not lead to a just and fair contract, we may need to call a strike and withhold our services until an agreement can be reached,” MDEA president Anita Johnson said in a statement.

MDUSD Superintendent Adam Clark said, “We are going to go through the impasse process and continue to bargain in good faith and we’re going to try to reach an agreement.”