I dive in Waterton all the time. I used to use tables, which you adjust with an altitude penalty. For example, when calculating your NDL, treat 100 feet depth as 120 feet. PM me if you are interested in the altitude penalties and I will hunt them down and email them to you. Alternatively, if you get a computer most computers will automatically account for elevation penalties. There are four very important things to note:
1. Your computer must be activated while dry in order to gauge your elevation. Most computers will automatically activate when plunged into the water. Unfortunately, if you use a wet activation your computer will default to the last elevation at which it was used. If you were at sea level for your last dive, your computer will be giving you dangerously incorrect information;
2. You must acclimatize to higher altitudes for your computer or elevation-adjusted tables to be correct. If you zip out from Calgary to Lake Minnewanka and jump into the water immediately, you will still have some residual N2 (from the higher pressure of Calgary) in your system. You will continue to off-gas while your body adjusts to the lower pressures at Lake Minnewanka. Your tables and computer will assume that you spent 12-24 hours at your current elevation, which is likely not the case. The difference is likely small (given the length of the drive and the time required to suit up), but you should bear this in mind;
3. Plan your post-dive travels carefully. You should avoid substantial increases in elevation after diving, especially in the first few hours; and
4. Cold water diving can complicate decompression and off-gassing. Starting a dive cold and ending it warm is not a problem. Starting a dive warm and ending it cold can be a problem (search for this topic on SB) as your body will off-gas more slowly than predicted by tables or your computer. Try not to red-line your NDL on cold dives.
Finally, buy a drysuit for local diving - you will love it.
A few articles for you:
http://www.scubaboard.com/forums/4882051-post25.html
http://www.scubaboard.com/forums/ne...ving/328008-i-know-another-gear-question.html