[M T]

Yeah, that subduction zone would seem to make it highly unlikely.  The earthquakes off shore would seem likely to break up any capstone above any fresh-water reservoir.   It seems the oil industry has explored so much of the US land area, that there would be no extensive water reservoir under the land.  I'm less sure that all of Canada's land mass has been explored as fuliy (that's a reflection of my ignorance).

[M T]

Yeah, that subduction zone would seem to make it highly unlikely.  The earthquakes off shore would seem likely to break up any capstone above any fresh-water reservoir.   It seems the oil industry has explored so much of the US land area, that there would be no extensive water reservoir under the land.  I'm less sure that all of Canada's land mass has been explored as fuliy (that's a reflection of my ignorance).