Never heard tell of KiddCreek until now and doing an internet search. Probably have driven around it while wondering around 1/2 lost looking for moose.
If they are smelting via electric arc then yes Hydro One will notice when they flick the switches on. KiddCreek may as well use lots of watts. There is not enough transmission capacity to send all the power from Northern & North Western hydroelectric sites south. If there is enough rainfall that is. Another two circuit 500KV line is required, it would assist Bruce Power transmission bottle necks as well.
Some of those hydro electric sites were given away to friends of those busy "improving" Ontario Hydro in the late 1990's. Not before most sites were refurbished for higher efficiency and greater output.