Grass needs soil, sunlight and water. When it's stressed, it needs more water.
We only have a very limited amount of water. Please stop watering the lawn from the faucet. That is potable water, and it's for drinking and washing.
The brown spots in the grass are mostly due to pocket gopher infestation. They dig underneath and eat the roots of the grass. It's really difficult for the grass to absorb water from the soil when its roots are in a gopher being digested. It stays alive for awhile, but it either needs to have lots more water, or no gophers eating the roots. Around the gopher tunnels, the soil around the grass roots is drying from both top and bottom, which makes it a lot harder to keep moist. Where the gophers push dirt up, they cover the grass and deny it sunlight, and the dirt absorbs heat and bakes the grass.
The other reason is sprinkler heads that aren't turning. This is where there's lots of grass but it's getting crunchy. Generally, there will be an hourglass shaped area of really really well watered grass adjacent to it.
I replaced another sprinkler head today, and there's another one on the east perimeter, that I'll do on Thursday. We'll keep an eye on it, but other than that, all the other heads are working. Also, the watering time has been pushed up a little bit. So we should be doing better, soon.