Being a History Teacher, in SoCal.... I have a different perspective. Im a Nebr Transplant, but have lived here in SoCal for about 20 years.
The movie only begins to tell the story of the murder, fraud, corruption and lots more done by many different organizations to gain some control of the water to Southern Calif. Including what is today the LA Dept of Water & Power.
The Eastern Sierra Mountains sheds snow which today drains to feed LA. LA would be only Omaha size had they not accumulated the rights to that water. Farmers along the Eastern Sierras were bankrupted and pushed off their land, on a daily basis, through threats, extortion, you name it, to get control of the water rights. People disappeared in the middle of the night. What was done to those folks who lived in those counties, was every bit as bad as done to the American Indians, 60 years prior, it was just a bit more subtle.
The movie certainly means more to Calif folks who know the history of what happened there. I didnt know, til I moved here. I make that 300 mile drive up to Mammoth Ski Area about 3 times a year, and you can see the Aqueduct system in place, you can see what there was once a massive lake, that is now drained out, because all that water went south, but the dry lake bed remains there now, 90 years later.
William Mulholland, was the engineer that designed the aqueduct system to provide the water to SoCal, he designed and built lots of dams, that created huge lakes to store the water. Sadly, one failed in 1928 or 29 if I remember, and an entire lake of approx 2000 acres roared thru a valley, killing approx 500 people. In actuality, It killed 3x that many, because they werent counting the undocumented migrant workers who lived there, and still do in that area today. Mulholland pretty much crawled into a whiskey bottle after that, he was never the same.