Get an identification. If it is an olive tree it could be quite valuable and considerable effort and expense might be indicated. If it is a Russian olive then it is widely regarded as a pest and you should expend effort and expense only if you want the tree.

Well, there's a closeup pic on google images that looks like mine. I looked at pics of Russian olive trees and mine doesn't have the yellow flowers nor clusters of olives. In fact, the olives are few and far between. I didn't even notice them the first month here. The birds seem to love them though.

Upon further searching I caught an article saying Clark County Nevada has a BAN on olive (and mulberry) trees. Say what?!!! The tree has to be decades old.

http://www.highbeam.com/doc/1G1-10380522.html

Looks like existing olive trees before the ban are allowed, but there is no way I can prove when it was planted. Looks like Arizona also has a ban on them. It's all because of the pollen. I've had pollen allergies since childhood but I have not had any problems since moving here from Louisiana. If anything, my allergies have cleared up.

http://www.8newsnow.com/story/1831408/olive-trees-the-good-and-the-bad