A massive waste water spill from a pipeline in northern Alberta will kill plants and trees, says an Alberta ecologist.

Suzanne Bayley, a professor emeritus with the University of Alberta who specializes in wetlands ecology, says the salt in the water will kill vegetation.

"It's going to be a big dead-looking area for quite a while, I mean certainly through this year and next," she said.

Waste water extracted during oil and natural gas operations contains oil, gas, salt and other minerals.

A pipeline operated by a Texas-based oil company leaked 9.5 million litres of industrial waste water about 20 kilometres northeast of Zama City, a community near the Northwest Territories boundary.

Bob Curran, a spokesperson for Alberta’s Energy Resources Conservation Board, said the spill was first reported by Apache Canada Limited on June 1.

"At this point it's not known how long the pipeline was leaking," he said.

"In the initial stages it was known there was some produced water into muskeg, no idea of what the volumes were but there was no indication the volumes were anywhere near the volumes eventually reported to us."

The company said the affected area is estimated at 42 hectares.

Apache said the nearby Zama River has not been affected by the leak, which has been plugged. The Zama River is a tributary for rivers further north, including the Hay River in the N.W.T.

But the Alberta government said some of the waste water did enter wetlands and some of the smaller tributaries which feed into the Zama River.

Members of the Dene Tha First Nation near Zama City are worried about the effects the waste water spill could have on their traditional territory.

The Dene Tha is made up of three communities and eight reserves, spanning 75,000 acres surrounding Zama.

"These impacts do have impacts on our traditional ways of being out on the land. Right from burial right to vegetations which we use for spiritual healing," said Sidney Chambaud, a councillor with the First Nation.

Chambaud said the area around the spill is an ancient hunting ground for the Dene Tha.

Rachel Notley, environment critic for the Alberta NDP, said the time it took for officials to learn about this spill and release information on it is unacceptable.

"The fact of the matter is if you drank this processed water you would probably die," she said. "If it kills things, it should not be allowed to run unchecked and it is the largest release of poison into the environment in the history of this province and this government took 12 days to tell us about it."

With files from The Canadian Press