I was on vacation a couple weeks ago, and ran into another landscaper. He told me he was not required to have an irrigation license in Oklahoma. He also told me they were allowed to spray hardscapes. Seems like one or both of these statements must be false. I somehow doubt they would let anybody draw up an install plan with no formal training on how hydraulics work, etc. I've poked around the net a little and haven't really found an answer. So, what's the truth here?