That sounds simple, but water rights, especially in the West can back further than it’s incorporation into the US. In the treaty that ended the Mexican America

That sounds simple, but water rights, especially in the West can back further than it’s incorporation into the US. In the treaty that ended the Mexican American war, the US agreed to respect all Mexican land grants. Those grants are still enforced by US law. Of course with eminent domain the government might be able to seize water rights (i don’t know) but owners would need to be paid a fair cost for the loss of those rights.