The election date was decided after Assistant Deputy Mayor Vern Tordoff raised the matter at council's Feb. 23 meeting.
"There's been some controversy on how to fill the vacant seat," Tordoff said.
Council could call a by-election, appoint a new member or leave the seat vacant, he said.
Glen Smart, who sat on council until his death Feb. 4 following a lengthy battle with cancer, had expressed the wish that former councillor Peter Maher be appointed to replace him, said Tordoff.
However, Maher, who lost in a bid to become mayor in last year's election, says there were some grumblings around town about the possibility of an appointment to fill the vacancy. He thinks the by-election is the proper decision.
Maher says it is hard to say if he would have accepted an appointment, a route that has been used by council in the past to fill vacancies.
"One of the concerns was that I had not run for council," he says.
Maher notes it is also very early in the term of council and an appointment might not be appropriate in such a situation.
However, he says he "absolutely" will run in the upcoming by-election.