The Master Surname Index (not online) (mostly burials in Alberta cemeteries) of the Alberta Genealogical Society lists, would you believe some 30 William JOHNSON's. Also some 30 KOCHAN names, but none near Rocky Mountain House.
For further research please contact the Research Committee of the Edmonton Branch.
http://abgensoc.ca/The Edmonton Branch
http://www.agsedm.edmonton.ab.ca/Peter