TransAlta and the provincial government have reached an agreement to use the Ghost Reservior west of Calgary for flood mitigation.

TransAlta has agreed to hold the reservoir at its minimum level until July 31 — six weeks longer than usual.

"By keeping the reservoir levels low, it means that we'll have additional capacity to contain a little bit more water should the circumstances reproduce as last year," said TransAlta spokeswoman Stacey Hatcher. 

The province estimates this would reduce peak flows along the Bow River by 100 cubic metres per second. That would be on top of the reduction of 400 cubic metres per second that TransAlta provided by other upstream reservoirs during the 2013 floods.

"Since then, we've been working with communities to strengthen our communications and prepare better. Today's agreement is just one more step in that process," said Dawn FarrelTransAlta's president and CEO, in a written statement.

Ward 7 Coun. Druh Farrell said the agreement is good news.

"A lot of people were worried that they weren't coming to the table and negotiating. And so it appears that it's been effective. For this year anyway," she said.

The government said Wednesday the agreement is for this year only.

Both parties will evaluate how well it worked after July 31 to determine if it should be a long-term deal.