City council has responded to an urgent call from a river valley conservation group to preserve a large swath of land in southwest Edmonton by making it part of the budget debate this fall. 

The North Saskatchewan River Valley Conservation Society's members fear development will soon encroach on The Big Island Woodbend area of the river valley, south of Anthony Henday Drive. 

"When it comes down to it, there's nothing that actually protects from development in the river valley," said society president Stephen Madsen.

Madsen and his group urged council to buy up the 400 hectares of natural area.

If council agrees, the group said Edmonton would have the largest urban natural area in Canada.

The city's executive committee asked that a river valley master plan be added to the budget debate this fall.

Coun. Michael Oshry said the city should act quickly, so it can get plans for the area right, before developers move in. He said he has seen first hand what happens when the city gets it wrong.

Many places in his ward have no parking at river valley access points, leaving users to park in residential neighbourhoods, he said.

"When it's too late is when ... neighbourhoods are a gong show because there's no appropriate place for parking," Oshry said.

He would like to see the plan finished before the city starts buying up the land, which the conservation society estimates will cost about $25 million.

Most of the land is privately owned right now, but can't be developed because it's in the river valley.

"Eventually the city is going to own that land. It's just going to happen," Oshry said. "It shouldn't be a huge rush to buy it."

Councillors will debate funding the master plan in the fall. If approved, Oshry guesses it will take about two years to finish.