How much water ( gallons per hour ) should mature avocado trees get per week?

Question:i live in central california, i have 3 spinner heads per tree and leave them on 1 1/2 hours per week. is that enough?

Answers:
Spinner heads will distribute the water over a large area and much of that will evaporate, try a drip hose and shoot for the equivalent of 1" of rainfall per week and a bit more during dry and hot spells. I wish I could tell the times that these types of watering sources such as sprinklers, drip, soakers etc... equal that 1" equivalent but I have been unable to find that information. You can generally tell the health of a tree by it's leaves are the curled up and dry looking or expanded and darker green with a healthy appearance. The roots that absorb the water for a tree are generally beneath the outer edge of the canopy.
:-)