Hi Debra, 
I apologize for my delay in getting back to you on this, it got lost in my crazy emails and I just found it! 
There are lots of factors that could contribute to this. We have had some odd freezing patterns the last couple of years that might have caused stress to the trees causing them to be more susceptible to diseases or Spruce Bettle or Spruce Ips. This could also be caused by the drought that we are currently in, we often see dieback from the top down and outside inward. Do you have any Firs on your property? The Douglas Fir Tussock Moth typically attacks true fir trees but has affected Blue Spruce as well (there is a picture in the factsheet below that looks very similar to the one you sent)
Here are a few factsheets that might help you check these trees carefully to see if any of the information described might be what is happening to your tree. 

https://extension.colostate.edu/topic-areas/yard-garden/environmental-disorders-of-woody-plants-2-932/

https://extension.colostate.edu/topic-areas/insects/5-542-douglas-fir-tussock-moths/

https://csfs.colostate.edu/media/sites/22/2014/02/Spruce-Beetle-QuickGuide-FM2014-1.pdf

https://extension.colostate.edu/topic-areas/insects/ips-beetles-5-558/

I hope that these resources help! Please feel free to reach out if you have additional questions! Again I apologize for my delay in getting these questions answered! 
Barbie