The extent of browning is concerning, and suggests that something more than just underwatering is happening, though it's hard to determine what exactly and how it began. Sometimes fungal canker infections (which could have begun weeks or months ago) set in after a wound occurs or after a plant is stressed by drought. You mention that the tree is getting regular water; is it checked at least weekly and, when needed, soaked thoroughly so the soil is re-moistened to a depth of about six inches? If not, it might be needing more regular or more heavy waterings. (If helpful, our Watering Trees and Shrubs page provides tips.)

It's hard to tell if it will recover (maybe not this summer, but in the spring), though there is little that can be done at this point to intervene aside from monitoring for watering needs. If the branches with dying leaves are dying themselves, then they would need to be pruned off. If only the leaves are lost but the wood lives, then it might leaf-out in a few weeks (or it may wait until spring). A "scratch test" of the cambium (the live layer of wood just under the bark) can help determine if leafless branches are alive or dead, but it's not foolproof as sometimes the cambium death is delayed after leaves are lost.

Miri