The Waterloo Region District School Board has 90 days to figure out how it will replace one of its longtime trustees.

The school board announced Monday that Andrea Mitchell, who represents Cambridge and North Dumfries on the board, has resigned her position.

A press release from the school board did not give any reasons for her departure.

Mitchell had been on the WRDSB’s board of trustees since 2001.

The remaining trustees will be given options on how to fill her seat on April 2017.

The last time there was a vacancy on the board in the middle of a term of office was in 2012. In that case, trustees chose to appoint a member to the board for the rest of the term.