Not the /only/ water problems... https://www.waterboards.ca.gov/conservation/regs/water_effic...
Agg uses like 80% of consumer water. Almost all of this is land that has only been farmed since the Feds build a bunch of water projects starting in the 30s.
Most of the irrigated farm land is owned by big corporations and extremely wealthy families. They push a narrative of mismanagement and shortages to get urban areas to use less and less while they resist investing in better irrigation methods.