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Right of Prior Appropriation


The right of prior appropriation is a legal doctrine used in the Western United States that the first individual to use water found in the region for “beneficial use” has the right “priority” to keep using it in future as compared to subsequent users.


The right of prior appropriation operates on the principle that no one owns the water found in the western states and that water rights will be awarded to users based on the dictum “first in time, first in right.”

Water rights in most of the states in the West of the USA are treated just like property rights and are considered independent from the land where the water flows and where it is used. Most of the western states are classified as being arid areas where water is scarce, which is what necessitated the implementation of the right of prior appropriation. Most of the water sources (streams) in these areas are seasonal.

Origins of the right of prior appropriation

This doctrine traces its earliest roots to the rush of Mormon settlers into Utah in the early 1800s, which forced the settlers to devise a system of allocating water resources for beneficial use on a first come, first served basis.

However, the legal doctrine was officially adopted by California in 1850 during the gold rush to allow miners to divert water from their natural waterways for use in mining. According to the doctrine, junior appropriators (later users) are prohibited from using the water from a stream if their usage activities will limit the water available to senior appropriators (first users) below their allocated rights.

How to acquire water rights

To acquire a water right, the user should appropriate (divert) water from its natural waterway and put it to beneficial use. The condition ‘for beneficial use’ means that he should use the diverted water for irrigation, industrial and mining activities, municipal and domestic use, and other economic activities that are not wasteful.

After acquiring priority rights to water under the right of prior appropriation, the dictum of use it, or lose it applies, which means that once you have the water rights you have to use the water in line with the conditions outlined, or you risk losing the rights.

Categories of water rights

There are two main categories of water rights, which are rights for storage, or direct flow. The right for direct flow is typically measured in terms of cubic feet of water flowing per second. Most states use the concept of the ‘duty’ or need for the water when assigning rights in order to prevent wastage of allocated water resources.

Storage water rights are usually measured in terms of the volume of water that a user is allowed to store in a large vessel for one year. They are usually limited by the size of the user’s reservoir and are generally allocated to fill the reservoir once every year.

Underground water

The treatment of underground water by Western states differs significantly with some states treating the ground water from springs and tributaries near the surface similar to their treatment of rights to surface water elaborated above. This means that users who extract water from springs and tributaries must abide by the water rights described earlier.

Some states treat water from underground sources such as aquifers as water that is not connected to any surface water system and as such is not bound by the water rights that govern surface water. In such cases, the user can extract water from such underground sources regardless of whether the needs of other senior appropriators are being met.

Many arid states have laws that designate specific sources of underground water as being critical water sources. This usually applies to sources such as aquifers that are major water sources for the municipality and agricultural usage whose water levels are declining.