Did they actually say 15? Or 1.5? If 15, that's completely erroneous.
As is obvious when you think about how much water comes out of the faucet to which the sprinkler is attached.
Sprinklers can be 25 gpm mine are around the house when all ten are running it uses the full output of a 250 gpm well pump.
My HE washer uses 15 gallons when not on deep fill cycle and no extra rinse. With both those on it’s nearly double at 28 gallons per load but I have city water for that and drinking with a irrigation well on property for everything outside including the pool hotub and sauna.Texas is a right of capture state I can pump my well till my heart’s content I don’t live in a groundwater control zone.
There is solid evidence via tree rings that California and the southwest have droughts that last for centuries it’s part of the climate cycle in that region. The water compacts were all drawn up during a period of unusual wetness not seen again over the last 2000 years. They need desal they should ask the Israelis they can desal seawater cheaper than the retail rates in any Texas City at under 60 cents a cubic meter.