Why not simply use pricing to ration use? This is by far the best method of distributing any resource of good or service.
Everyone simply should pay the same price per gallon. Businesses that have been abusing the system to get nearly free water will yell and scream, then go find something more productive to do.
Water rights should not be rights and usually aren’t rights… Water is owned by the state. The state should just be a utility that charges whatever price it desires to achieve the goals it has. If it wants to reduce water use, raise the price