George Smitherman, who took over the energy portfolio in a cabinet shuffle last month, will direct the Ontario Power Authority to line up a natural gas supply for a new plant and announce a process for deciding where it will go.
"It means a new plant," said a source close to the announcement, which will be made near the site of the old coal-fired Lakeview Generating Station demolished last year.
The 800-member Lakeview Ratepayers Association has fought against putting another power plant at the Lakeview site, still owned by Ontario Power Generation.
Mississauga City Council voted unanimously in February to approve a citizen-driven plan to build a $2 billion waterfront community on 200 hectares around the site.
The province "took so long to make up their minds we decided we weren't going to wait any longer," said Mississauga Mayor Hazel McCallion.
Crown-owned Ontario Power Generation has been lobbying to build a natural gas-fired power plant at Lakeview, saying it will be much cleaner and smaller than the old plant.