[Morrigoon]

I've had singing lessons. They are absolutely beneficial.

The wrong technique can create bad habits and ruin your voice. Some piano teachers are also singing teachers and I'm sure there are good ones, but, if you can, find someone who really focuses on voice. Many are singers themselves, some are not. But you'll find the ones who are not themselves singers, and are focused on teaching voice, are probably out of price range for most people (example: Seth Riggs)

Believe it or not, I found Robert Edwards through the phone book, but this is not the traditional way to go about it. You're best off asking around for referrals. (However, if you can't find any referrals, take comfort in the fact that anyone willing to pay good money for advertising is probably professional and not just doing this on the side).

The good news is, even in the Inland Empire, you're close enough to LA to benefit from proximity to it, in terms of the likelihood of finding a real professional. Look to your local large theater, and see if someone from their masterworks chorale can recommend someone. There's a strong chance that somebody within the chorale will themselves be a teacher.

Oh, I should mention... have your daughter determine what her end goal is. Not in terms of professional achievement, but in terms of what STYLE of music she wants to move her vocal technique towards, because that will have some impact on the lessons she receives. And she should be able to convey that goal to the potential teacher. Also, don't be afraid to schedule a single lesson with a couple teachers and go with the one you like best.