Winnipeg had planned to sell the water to a couple of nearby communities.
But the IJC the plan is inconsistant with its century old agreement.
Chief of Shoal Lake #40 First Nation, Erwin Redsky says they warned the City over a year ago that they did not have the right to use their land or the water for profit.
He says they will oppose any further application by the City of Winnipeg to the IJC.
