Simply not true. Only 14% of California water goes to residential use, and that includes lawns. 6% goes to industry and 80% goes to agriculture. You can blame illegal aliens for a lot, but the water shortage is not one of them.
If so many tens of thousands of extra consumers are getting access to water, over and above the census figure... how can anyone be certain HOW much water they are consuming.
So into which of those three categories do the 1,140 golf courses fall?