Help with young spruce

[mu51c10rd]

We planted a Spruce a few years ago in the front yard. It looks like the bottom limbs are dying around, the needles go brown and fall. I've been keeping it watered, and have sprinklers as well. Should I trim it or is this a sign of some type of disease? If I trim, how do I properly trim it? If it is a disease, how do I treat it? I attached some pictures. Thanks for any help...