Understanding the Doctrine of
Prior Appropriation

What is a Water Right?

A water right is the right to use surface water, groundwater or other water resources. Each state has different rules that define water rights. For most Western states, water rights are based on the principles of prior appropriation and beneficial use.

What is Prior Appropriation?

Prior appropriation allocates water rights based on timing of use, place of use and purpose of use. It allows for diverting water from its source to fulfill water rights and determines who gets water during times of shortage.


Senior Right

A claim to water that is older (more senior) than those of junior rightsholders. Prior appropriation grants rights based on a priority date. The older the claim, the more secure the right. Senior water rights are often associated with farming, ranching and agricultural uses.

Junior Right

A claim to water that is more recent than senior rightsholders. Junior rights are fulfilled after all senior rights have been met. Junior rights are often associated with municipal, environmental or recreational uses. However, senior rights may be bought to secure priority status.

Vested Right

In Nevada, vested rights are claims to water that were established before state law required rights to use water. These rights are commonly associated with homesteaders in the rural West. Vested rights have priority over senior and junior rights and are highly valuable.

Federal Reserve Right

When land is withdrawn from public domain by the federal government for tribal reservations, national forests or national parks, it holds a federal reserve right. The date that the land was founded or settled by the federal government is the date of the associated water right.


What will you use water for?







Several other options for use, depending on federal or state regulations.


Once you have acquired a water right, this means you have been granted “paper water” -- the legal claim to a specific allocation of water for beneficial use.


paper water isn't wet water

“Wet water” is the actual, physical amount of water that is allocated for use in a given year based on your water right. However, during times of shortage some water rights may not be fulfilled.


Priority Rules

A junior water right may be reduced or postponed until a senior user fulfills their total allocation. This is based on water availability and is known as water right curtailment.

Use It or Lose It

Beneficial use defines the amount of water that is necessary to meet the stated use. Some water rights might be forfeited if a user’s full allocation is not used each year over a period of five years.

Federal Regulation

Laws such as the Endangered Species Act can impact water rights. For example, if water use threatens a protected species’ habitat, then curtailment of some water rights may be required to protect it.

Request PDF Version

If you would like a copy of the PDF version of this infographic, please email Kerri Jean Ormerod at kormerod@unr.edu

Hockaday, S. and Ormerod, K.J. 2020, Western Water Law: Understanding the Doctrine of Prior Appropriation, Extension | University of Nevada, Reno, IP-20-01

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