The province is going to renew its monitoring of creosote levels in West Hillhurst for the next five years, but Calgary's mayor says the time has finally come to clean up the source of the decades-old waste next to the Bow River.

The contamination migrated under the Bow River from the site of a former wood preserving creosote plant that operated on the south side of the river from 1924 to 1962 just west of the current Greyhound bus station.

The contaminated soil was walled off underground in the mid-1990s, but it was never cleaned up.

Testing between 2010 and 2014 found no risk to people or fish, the province says.

"However, the province is funding this long-term project to better understand the scope and nature of the creosote in the community and along the Bow River," Alberta Environment said in a release.

Canada Creosote Ltd., later known as Domtar Corporation, operated a wood preserving operation in the circled area from 1924 to 1962, leaving behind creosote contamination in the soil and groundwater. (Google)

The monitoring program will cost $1.3 million over five years. The government says its first report will be available in mid-2018.

Time for cleanup, mayor says

Mayor Naheed Nenshi says the ultimate goal must be for the contamination to be cleaned up.

"I think we've had successive governments — at the municipal and at the provincial level — kind of think that containment was enough, that monitoring was enough," he said.

"And I think what we're really seeing both from the city and from the province is, you know what? We actually can't just contain it. We really have to move towards cleaning it up."

The need for a costly cleanup of the creosote in the ground on the south side of the river was one factor in a so-far stymied proposal to build a new arena and stadium complex in the West Village.

In 2015, the Calgary Sports and Entertainment Corporation (CSEC), which owns both the Flames and Stampeders, proposed CalgaryNext, a multi-sport complex that would include a new NHL arena, a new CFL stadium and a public fieldhouse, for the area.

The estimated cost of cleaning up the creosote to make way for the project has been pegged as high as $300 million, and it's not clear where that money would come from.