My experience for September 2011, 2012, and 2013 in the area pretty much matches up with previous posts.....
All campgrounds I stayed at were no reservations no problem :
2011 - Lake Louise (elec hookups) two consecutive days
2011 - Whistlers (no hookups)
2012 - Tunnel Mountain I (no hookups)
2012 - Lake Louise (elec hookups)
2012 - Whistlers (no hookups)
2013 - Columbia Glacier (no hookups)
2013 - Tunnel Mountain I (no hookups)
2013 - Two Jack Main (no hookups)
Footnotes :
Whistlers (elec hookup) sites were full in 2011, 2012, and 2013
Tunnel Mountain II (elec hookup) sites were available in 2012 (which I declined), but sites were full in 2013
Tunnel Mountain III (full hookup) sites were full and or closed in 2011 2012 2013 if my memory serves right
Two Jack Lake sites were full in 2013....Two Jack Main was open final day of season before closing (only three sites were occupied including me)
So in other words, (other than Lake Louise campground with plenty of elec hookup sites readily available) for those that really need electric hookups elsewhere where campgrounds remain open during September...then I would recommend reservations.
