Considering most of CA water comes from Colorado and Nevada...
Less now than before. When the Co River was apportioned, the upper states did not need all of their share, so CA was allowed to use that until the upper states did need it, which was around 2006/2007.
That was a major event at the time and there were some serious conflicts between growers in the Imperial Irrigation District and the San Diego golf courses.
No doubt losing that water contributes to CA's problem today.
This includes a changing definition of "highest beneficial use".
No doubt that, previously, farming or watering stock was highest, but today, recreational water probably generates a bigger economic engine. Tourists wanting to golf, fish for trout or salmon, and down river boaters are willing to pay top dollar.