Large areas of China, Egypt, ect have been under continuous irrigation for thousands of years and they can still grow just fine. If California is having issues

Large areas of China, Egypt, ect have been under continuous irrigation for thousands of years and they can still grow just fine. If California is having issues with irrigation over what 100 years then it's a separate issue. They probably do have issues due to the amount of rainfall vs. irrigation and their crop rotation etc. But, it's not really an issue with irrigation just their approach to irrigation. Desalination also gives you the option to have much lower salinity than river water which should allow areas like California to cope with this issue.