In Washington State, water is allocated according to a prior appropriations system, which means that a water right is set forever at a certain amount.
Some irrigation systems are very inefficient.
By using more efficient systems, farmers can divert less water to irrigate their crops, and appear to be saving water. Representative Gary Chandler drafted House Bill 1113 in response to water shortages, particularly in the Yakima Basin, where orchardists with junior water rights have been seriously short of water in drought years. If you're allocating it, and it really isn't a surplus, you're allowing an upstream user to use a downstream user's irrigation right. Huffaker said he is concerned that the state of Oregon has defined conserved water as the difference in diversions before and after efficiencies have been made, and it looks as if Washington will do likewise. If farmers use inefficient systems, senior users receive their allocations, but junior users in a district do not get their full amounts when there are shortages of water.