I went and looked at a valley oak tree a couple of days ago. It is in it's last death throes. Maybe 5% of the limbs had any leaves. About 30" dbh and about 45 feet high with a spread of 40 feet or so. It had a huge limb that ripped off (estimated 12" dia.) up about 20 feet high some time ago and several of the lower limbs cut off and about 10% closure of the wound. It sets about 10 feet in elevation higher, and about 200 feet from the Merced River. So it has the typical east side of the valley type riparian soil which is river rocks, sand, and it is down in the flat land so it has a little loam in there. It has a good root flare and one small wound on that probably from a mower. About 15 years ago they planted turf around the base of the tree and irrigated it almost year round for about 10 years. Then five years ago they decided it was taking too much water/electricity and quit watering the turf. This is when the tree started going downhill. I'm thinking that either the watering aggrevated some Oak Root Fungus and the root system was so compromised when they quit watering that it couldn't support the tree. As I said there it is probably only 10 feet or a little deeper to tap into the river water. What say yous guys. Is this enough info to go on? No pictures, sorry.