The City of Regina is spending $340,000 on a major advertising campaign in a bid to sway next month's wastewater treatment plant referendum vote.

Newspaper and radio ads, billboards, and now even robocalls are encouraging residents to vote "no."

Regina Mayor Michael Fougere confirmed in a news conference last week that the city would use taxpayer dollars to fund a "no" vote campaign.

The spending was authorized by the city manager, but it hasn't been approved by city council.

The referendum centres around the funding model for the $224 million project to upgrade the city's aging sewage treatment facility. 

It comes after council's approval of a public-private partnership funding model for the project in February prompted a petition by the group Regina Water Watch.

Residents are tentatively set to head to the polls Sept. 25.