FYI: Came home to find water pouring out of sprinker junction box.
I turned off the water main... the valves on the sprinkler junction box were rusted/corroded and couldn't be turned.
Called College Station Sprinkler Repair and owner walked me through finding a round "valve box" that I didn't even know existed (grass was grown over and it was covered in 3 inches of dirt.)
He was going to come out if I couldn't find that. Essentially cost himself $150 diagnostic fee to help out (it would have been applied to the repairs I needed, but still great customer service), and I would have felt stupid knowing it was as simple as turned that big valve that was in that box.
So... here's a hearty recommendation for College Station Sprinkler Repair.