Hi, this is Steve and thank you for your Ask Extension question concerning your Blue Spruce and purple needles. It’s often difficult to diagnose issues from photos, however, I am leaning toward a fungus infection called Rhizosphaera needle cast which can cause brown or purple needles. I’m attaching information from New Mexico that does a good job of describing the condition, how to use a magnifying glass to diagnose and treatments using fungicides.

https://pubs.nmsu.edu/_h/H163/index.html

Another option for a definite determination if your spruce has a disease is to send a sample to CSU for analysis. I’m including a link to do so, however, I am unsure of a current charge for the service but there is contact information on the web page. https://agsci.colostate.edu/agbio/plantclinic/submit-sample/

Overall, from the pictures, it appears the spruce is healthy except for the discoloration. There is always the possibility the tree could be having an issue with winter injury which good care this spring and summer could mitigate.

Again, thank you for your question and feel free to contact us any time.