Ellen, Before adding water to your tree, check the branches for a whitish substance at or near base of needles.  There may be insects causing browning of the needles.  I am sending a fact sheet about spruce trees from CSU: cmg.extension.  colostate.edu. https://extension.colostate.edu/topic-areas/insects/ips-beetles-5-558/  

Cooley Spruce Galls – 5.534:  

Plant talk is another resource for pines: 2123 – Needle Browning of Evergreens.

Before you water, and if none of these information pages answer your concerns, you can talk with an arborist. I hope this helps you.

Master Gardener.