And I notice most of the things you mentioned involve the farmer selling the rights, the power currently belongs to the farmer. Yes, the government could change it but I don't see it happening, there doesn't seem to be the political will to force the issue.
As for the family involvement, the farming part of it is largely past tense but the family has also had lawyers and been political, and they literally helped write and create a lot of the water laws.
There are also some fun stories, such as my great great great grandfather getting "excommunicated" for taking his turn with the water. 😉