As this editorial from August 2013 shows, there were serious concerns about Manitoba Hydro's plans even then: See
Notably,"The utility has always insisted building the Keeyask and the massive Conawapa dams is a must-do because Manitoba will run short of hydroelectricity for domestic consumers."
"The $6.2 billion Keeyask generataing station" - It is now projected to be $8.7 billion.
Indeed it believes the construction of Keeyask "will draw $29 billion in export revenue in the next 30 years."
Hydro used a consultant's report from the Brattle Group that "the long-term export price will rise to almost $70 per megawatt-hour from $30 by 2034." Because under the present circumstances with Keeyask now seen as not needed for many years into the future and its greater cost of generation being about $120 per megawatt-hour, Manitoban's will have to continue subsidizing this boondoggle with increased rates.
Keeyask's excess energy has to be diverted into Manitoba to build it economy. So far as carbon emmissions are concerned, for a given amount of Keeyask energy if it is used to run an electric vehicle or bus locally, it will reduce emissions three tomes more than if that energy was exported to the US and used to cut back the emmisions of a natural gas generator there.