"Ahnee, Bon Soir, Bojoo.
We’re gathering on the traditional territory of the Mississaugas of the New Credit."
So begins speeches in Toronto by Toronto's Premier, Kathleen Wynne. 
In March, 2013, Ontario Power Generation (OPG) announced, "Ontario’s new Niagara Tunnel is producing more clean, renewable, low-cost electricity at the Sir Adam Beck generating complex." The project had seen delays and early budget overruns which pushed the project cost up to $1.5 billion. The payoff for the work was to be "about 1.6 billion kilowatt-hours."
OPG announced the project complete and in service in March 2013. The growth in annual (12-month) production was ~600million kilowatt-hours, or 0.6 terawatt-hours (TWh). While this is less than 40% of the promised 1.6TWh, it is still presents far too favourable a picture of what happened after the tunnel entered service.