Washington State Ferries faced major service disruptions Monday after 23 engine-room workers called in sick and employees qualified to replace them declined the assignments, the agency said. The workers are represented by the Marine Engineers’ Beneficial Association. Union representatives said they were unaware of the number of callouts until they learned about the disruptions through media reports. The union characterized the staffing problems as a crisis caused by WSF management. The union said engine crews once had an extra worker, allowing a vessel to sail when one person was sick. It said management pushed to end that practice, leaving crews at the legal minimum and requiring emergency replacements when an engineer calls out. WSF said its vessels are staffed at the beginning of each service day at levels required by the U.S. Coast Guard. When workers call in sick, dispatchers try to fill the openings as quickly as possible, the agency said. The union also criticized what it described as heavy reliance on mandatory overtime. Some members work more than 1,500 overtime hours a year, according to the union, while dozens exceed 500 hours. Roland Rexha, the union’s secretary-treasurer, warned that fatigue could put workers at risk and said some members are considering leaving for other jobs. Pay has also been a point of contention. WSF said staff chief engineers earn a base salary of $157,000 and can make more than $350,000 annually with overtime, in addition to sick leave, vacation and retirement benefits. Rexha said that level of total pay would require an excessive amount of overtime and was not safe. WSF said its operations, dispatch and crewing teams were working to fill relief requests and return as many vessels as possible to service. It did not provide details about which routes were affected in the information released Monday. The disruptions underscore how shortages in specialized crews can affect ferry service relied on by communities across the state.