The river valley running through Edmonton and neighbouring communities would be turned into a giant park and playground under a plan being pushed by the region's municipalities.

The River Valley Alliance, made up of councillors from seven municipalities, wants to create the Capital Region River Valley Park, which would stretch along the NorthFort Saskatchewan River for88 kilometres from Devon, through Edmonton, and all the way to Fort Saskatchewan.

The alliance unveiled its latest plan for the park on Thursday, with chair Sol Rolingher promising the proposal won't sit on ashelf andgather dust.

"I think it's going to be around for generations to come," said Jo Szady, a councillor with Parkland County on Thursday. "The biggest, and best, park I think North America has ever seen."

Cost estimates are already at a staggering $605 million. Almost half that would go to buying up land for the park, landscaping and adding more trails. The rest would be used to fix up existing attractions and build new ones, such as an outdoor amphitheatre.

The communities involved say they're ready to put the necessary money into the plan, but realize they're going to have to convince the province and even Ottawa of the river valley's potential.

"We have to be so cognizant and be aggressive in making sure this happens because we don't want it to fall off the table," said Linda Osinchuk, a councillor in Strathcona County.

The plan still needs to get the official approval of all the municipalities involved. Open houses on the project will be held across the region with more details, starting April 10 in Devon.