There have been no snow samples taken in recent years, certainly, except for water content. Environment Canada and Alberta Environment both have small monitoring programs. Both have been jeopardized year after year by successive budget cuts, to the point that, the last I heard, Environment Canada was down to monitoring very infrequently at only one station on the river, downstream of the oil sands plants.
Of course, it's easy to say that it's “all natural”, if you don't have a program that is intense enough to separate natural from industry sources. I'm hoping that as a result of the work we've done, that program will be upgraded, because they have very good people and the right expertise and equipment to do a really good monitoring program.