Put in the simplest form, prior appropriation essentially means “first come, first served.”
Under this doctrine, the first person to appropriate water (in compliance with state statutes that generally require a permit be obtained to do so in most instances) and put it to a “beneficial use” acquires a right to use the water for that purpose.
Importantly, a water appropriator does not acquire ownership to the water, merely a right to use the volume of water he or she has put to beneficial use.
That person’s right – established when he or she first began appropriating water for beneficial use – is then senior (or superior) to subsequent water rights.
When water supply is insufficient, such as in times of drought, the junior rights must cede to the senior rights.
In this situation, a senior water rights holder would receive all of the water to which he or she was entitled before a junior water rights holder would receive any of his or her allotment.
Seventeen states use prior appropriation in some form to govern at least a portion of the water within the state:
Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington and Wyoming. The laws and regulations vary greatly even among states utilizing prior appropriation.
Some states, such as New Mexico and Colorado, apply prior appropriation principles to both groundwater and surface water.
Other states, like Texas, use this principle only for surface water and use a wholly separate doctrine (the rule of capture) for groundwater.
Additionally, states have different approaches with regard to exceptions from the prior appropriation permitting process.
In New Mexico, for example, certain wells are considered de minimus and allowed to forego the extensive permitting process generally required.
Thus, an applicant for a domestic or livestock well in New Mexico is automatically granted a permit upon application, with no investigation or analysis into the impact the proposed well might have on senior water users.
Conversely, Utah does not recognize any exceptions – even for de minimus uses – and requires all wells to comply with the full permitting process, including a study into the impact on senior water holders in the basin or aquifer.
Controversies have been common across the West about this doctrine in recent years. In New Mexico, a farmer and senior water rights holder claimed the state’s exemption for livestock or domestic wells from the permitting process was unconstitutional.
Last year, the New Mexico Supreme Court upheld the statute as not interfering with the constitutional principle of prior appropriation.
Currently in Texas, several disputes are ongoing with regard to exceptions from the priority doctrine in times of shortage granted to municipalities, power generation facilities and domestic wells, at the expense of senior users.
Many legal scholars question the functionality of prior appropriation going forward, particularly given increasing populations, severe drought and environmental issues surrounding water.
Critics believe the doctrine to be arcane and ill-suited to address and balance the diverse interests of water users today.
For now, however, the doctrine is the law of the land across most of the West, and producers should be familiar with the doctrine and their related state-specific laws and regulations. 
Tiffany Dowell
Assistant Professor and Extension Specialist Agricultural Law
Texas A&M AgriLife Extension Service
