Honestly it sounds like a conspiracy theory to me. I'm sure companies are buying rights to water, but I suspect it's for straightforward near term interests, like, say, Poland Spring's owners buying water rights so they can sell bottles of water - not because they think they will be our overlords in 20 years or whatever.
I receive internal company newsletters that talk about the need to get more water contracts due to climate change and the opportunities/competition ahead. It's not conspiracy, it's commerce. Like real estate, you buy it now when it's cheap because you predict it'll be worth a fortune in a decade or two.
Contracts with whom?
They can’t just seize the water rights, they would have to purchase them at fair market value. Land with perpetual water rights happen to be worth *a lot* of money, which is why there haven’t been more government entities buying out current holders of water rights.
Step 2: Let market for these properties crash
Step 3: Buy at FMV
Isn’t that what fruit companies like delmonte did to Central America in the mid 20th century? Seizing all of the farmland with the support of the government to grow fruit for Americans?