Lisa Armstrong, Sarnia's direcor of finance, is resigning.
Her last day of work will be February 22.
Armstrong's resignation was submitted on Thursday and she said that after three years of working for the City of Sarnia she recognized that the political environment was not for her.
Mayor Mike Bradley said the departure date leaves plenty of time to help council through the hiring process.
Armstrong is the second senior manager at city hall this month to announce plans to leave.
City Solicitor Scott McEachran, whose last day is Jan. 4, submitted his resignation Dec. 3.