Hi There,
Thank you for contacting the Master Gardener office with your concerns about your beautiful blue spruce.  I have a few questions for you.  How old is the tree? Has it gotten winter water?  Are there any noticeable signs of insects or funguses?  And, when did it start to decline?
Also, many trees in the front range have been stressed due to the fact that in Oct. of 2019 temperatures dropped over 50 degrees in 24 hours.  Then we had another dry winter and in April 2020 there were 2 days of record lows.  All of this has taken a toll on our trees and plant material.  Trees that were already stressed from previous issues took another hit with the weather.  
Thank you for responding to the questions.  That will help us better diagnose the problem.
 

I am sorry to see such a majestic old tree in such distress.

If there was no damage this spring, then it is unlikely (but not impossible) the damage is from the fall early frost and spring extreme freezes.

There are insects which can cause this kind of dieback.   Try to get as good a look as you can for insect infestations, including any webbing on the tree.

Given that major tree roots were severed last fall (right before the freeze?), I think it is likely that the root damage is the culprit. It is also possible that the soil was compacted when the power line work was done. Compaction can slowly suffocate a tree, because it prevents the roots from bringing in oxygen.  

Given the rapid decline, I would suggest bringing in a certified arborist to look at your tree. Some will come and make a free assessment of the problem and whether it can be treated. You can find a certified arborist at:

https://isarmc.org/Find_a_Certified_Arborist

While you are waiting for an arborist, make sure that your tree gets the proper amount of water but is not overwatered. Overwatering can cause oxygen depletion just like compaction.   Generally speaking, a mature tree needs 10 gallons of water per inch of tree diameter, but you need to adjust this for your actual conditions.  To avoid overwatering, it is best to use the screwdriver test. Take a slender screwdriver and poke it into the soil in several places around the tree, both inside and outside the tree’s dripline. If the screwdriver can easily penetrate the soil to a depth of 6-8 inches, there is no need to water.

Good luck! I hope it can be saved!