I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. My name is ***** ***** I’m a biologist with a special interest in arboriculture. I'm sorry to hear of this incident. Your question is more complex than simply too much or too little water.
Unfortunately, the symptoms of too much water and too little are very similar. That's because both result in the roots being unable to transfer water upward to the leaves. With too little water, of course, there's no water to transport. With too much, the soggy soil results in pathogens growing in and clogging up the roots, resulting in no water being transported. Sometimes the two can be distinguished by the look of the leaves when the problem first begins. Lack of water usually results in wilting. Too much water often causes yellowing as a first symptom.
If the gophers are digging tunnels near the trees, they may have damaged the roots, making water uptake difficult.
Carrotwood trees are not subject to many pests, but curling leaves are often the result of pests. Some are so small they can only be seen with magnification. Fungal infections can also cause curling leaves.
This is not something which can be diagnosed online. Samples of the leaves need to be examined under magnification, and it would also be best if an expert could come out and look at the trees and your growing site. Some states have county extension agents who will do this at no charge, but California doesn't seem to be one of them. However, San Diego County does have a Master Gardener Helpline. This program may be able to send someone out to help. At the least, they will know of all the local resources. For that reason, I recommend that you give them a call at:
Master Gardener hot-line at(###) ###-#### *****'s free!
Another option would be to take some leaf samples to a local nursery to see if they have a microscope to examine them.
If you have more questions, just let me know. I hope you'll quickly be able to use the resources above to find a solution.