Further research and some input suggests this is a Pale Snaketail. A Sinuous would have a broad stripe on the thorax, whereas the Pale has that dark spot.

Sinuous Snaketails are fairly common around our area....

I was just looking at this one again, Paul. I agree that the thorax looks much more like O. severus. However, the abdomen is much darker than any images of O. severus that are in the guide or than any individuals I have seen in Alberta. Many of those I have seen were freshly emerged so perhaps even paler than usual? My experience with the species is limited in time although I have seen dozens of individuals. Are there any records of hybrids between the 2 Ophiogomphus species in your area?

Ken: I cannot find evidence of hybridization, but this one does seem to exhibit traits of both severus and occidentis. However, according to BC's E-fauna data, severus is much more widely distributed throughout BC, and particularly in my area and to the east. The Occidentis seems restricted to the Okanagen valley (200 km west) and very restricted in the Pend d-Oreille valley, both much drier areas. Photos in E-fauna seem to show more black on "severus" and the thorax does seem more like "severus" which match up with my individual.