THE FUTURE OF WATER LAW: WHAT HAPPENS WHEN CLIMATE CHANGES THE RULES?

摘要

West of the Mississippi River, water law is generally based on the principle of prior appropriation, meaning the first person to obtain a water right on a stream is the last to be shut off in times of low stream flow. This approach to water law anticipates the very real possibility of water scarcity, and sets forth a prescribed system to manage water during times of shortage. In water-short times, the water right holder with the oldest date of priority can demand the water specified in the water right, regardless of the needs of junior users. The water right specifies the location, time of year, and amount of water to be put to beneficial without waste. If there is a surplus beyond the needs of the senior right holder, the water right holder with the next oldest priority date can take as much as necessary to satisfy needs under this next water right and so on down the line until there is no surplus or until all rights are satisfied. This has the effect of providing certainty to senior water users, by ensuring a source of water that will support their economic investments.