The fight over the controversial Quill Lakes water diversion channel is now headed to the courtroom.

The Pasqua First Nation has applied to Saskatchewan Court of Queen's Bench for a judicial review of the provincial government's decision not to order an environmental assessment of the project.

In a sharply worded 20-page document filed on Tuesday, lawyers for the First Nation say assistant deputy minister Wes Koytk "is playing favourites with his political supporters" by not ordering a review.

Parse the full court filing here

Asked to elaborate on those bold claims, lawyer Ryan Lake of Maurice Law — one of two law firms tapped by the Pasqua — said he would do so once the case is argued in court.

A judge can't decide on the application until both sides take part in a courtroom hearing.

No comment from province

The Ministry of Environment declined to comment Friday on the accusations or the application for the same reason cited by Lake.

The water diversion project is being proposed by a coalition of landowners in south-central Saskatchewan who want to prevent further erosion of their lands from floodwaters from the Quill Lakes.

A sign that recently appeared in Craven, Saskatchewan, in opposition to the drainage project. ( Auralee MacPherson)

To do that, they want to build a 25-kilometre channel diverting water to Last Mountain Lake, a downstream lake around which the Pasqua First Nation has reserve land.

The band is worried about salty water travelling downstream and threatening Last Mountain Lake's fish and bird population.

Tilted toward developer: U of S prof

Maurice Law and its partner on the case, Toronto-based Fogler Rubinoff, also charge Kotyk with "deliberately" ignoring public concerns about the project before deciding to exempt it from an environmental assessment.

Jason MacLean, a University of Saskatchewan professor who specializes in environmental law, said the minister's decision was tilted toward the Quill Lakes Watershed Association, the group of landowners behind the project.

Jason MacLean, assistant professor at the University of Saskatchewan's law college. (University of Saskatchewan)

"The minister's decision … embodies the dysfunctional pathologies of Canadian environmental assessment practices," he said. "It has been driven by, and in favour of, the project proponent, with the result being seemingly predetermined.

"Meanwhile, the public — including the public interest in transparent and evidence-based decision-making — is undermined. In this case it has been ignored altogether."

Among the other charges against the province is that it made its decision about an environmental assessment while very little information about the project was released to the public.

Lawyers also say the province broke with Section 35 of the Constitution by not adequately consulting the First Nation, though Kotyk previously told CBC the decision over whether to order an assessment didn't trigger the duty to consult.

"The Pasqua expressly asked to be consulted with respect to the project. This request was ignored," wrote Jack Coop of Fogler Rubinoff in the application.

The Pasqua also want an injunction stopping construction of the channel from happening until the judicial review case plays out.

Feds mulling their own review

The request for a judicial review comes even as Canada's federal regulator, the Canadian Environmental Assessment Agency, is making up its own mind on whether an environmental assessment is necessary.

CEAA says it expects to make that call in early 2018.

Coop said the application for a judicial review was filed in case the federal government agrees with Saskatchewan that an environmental assessment isn't necessary.

The University of Saskatchewan's MacLean says the federal government "almost never" gives a proposal its own sniff test after a province has passed on doing an environmental assessment.

The ministry said last month that it stood by its decision, which was informed by the input of a panel of experts.

No other groups besides the government and the Water Security Agency, which is a Crown corporation, were represented on that panel.