SAN FRANCISCO — It’s hard to be a prosecutor in Contra Costa County.

One of the lowest-paying offices in the Bay Area, it’s also one of the hardest-working. A staff of 89 attorneys prosecutes crimes in a community of well over a million, and those attorneys are sometimes hired on a temporary basis without benefits, a pay structure deputies say does little for loyalty. The latest blow to the office came from the Board of Supervisors, which last month approved a 5 percent pay cut. That has the attorneys union contemplating a strike.