Question on catenifer sub-species ranges
 

I read that P.c.catenifer and P.c.deserticola ranges over lap in southern Washington State. My question is are the gopher population in Yakima county, WA.(link to map attached) more then likely Intergrades? Or are they more likely pure deserticola?
And how far north of a WA. state locale would be safe to call pure deserticola? any thoughts would be appreciated
Thanks
http://www.lib.utexas.edu/maps/states/washington.gif