What is a Water Right?

Public Waters

The constitution and statutes of the State of Idaho declare all the waters of the state, when flowing in their natural channels, including the waters of all natural springs and lakes within the boundaries of the state, and ground waters of the state, to be public waters.

The constitution and statutes of the State of Idaho guarantee the right to appropriate the public waters of the State of Idaho. When a private right to the use of public waters is established by appropriation, a water right is established that is a real property right much like property rights in land. The constitution and statutes of the state of Idaho protect private property rights, including water rights.

A water right is the right to divert the public waters of the state of Idaho and put them to a beneficial use, in accordance with one’s priority date.

Priority Date

A priority date is the date the water right was established. How this date is determined is described in the section below. The priority date is important because the priority date determines who gets water when there is a shortage. If there is not enough water available to satisfy all of the water rights, then the oldest (or senior) water rights are satisfied first and so on in order until there is no water left. It is the new (or junior) water rights that do not get water when there is not enough to satisfy all the water rights.

Beneficial Use

Beneficial uses include such uses as domestic use, irrigation, stock-watering, manufacturing, mining, hydropower, municipal use, aquaculture, recreation, fish and wildlife, among others. The amount of the water right is the amount of water put to beneficial use. Due to the beneficial use requirement, a water right (or a portion of a water right) may be lost if it is not used for a continuous five-year period.


A diversion is a structure used to divert the water from its natural source. Typical diversion structures include pumps, headgates, ditches, pipelines, and dams, or some combination. A diversion is generally required to establish a water right. The Idaho Water Resource Board is authorized to acquire water rights without diversions. These water rights are called “instream flow” water rights, and are typically authorized for purposes of protecting some public interest in a natural stream or lake, such as recreation, wildlife, or natural beauty. A water right may also be acquired to water livestock directly from the stream, which is called an “instream livestock” water rights.

Water law in Idaho is based on the appropriation doctrine, because water rights in Idaho are based upon diversion and beneficial use of water. The appropriation doctrine has also been called “first in time is first in right”, because the priority date determines who gets water when there is not enough to go around. The water right is said to have “appropriated” water.

Riparian Rights Not Recognized in Idaho

You may also have heard of something called “riparian rights”. In some states, an owner of land has the right to make a “reasonable use” of ground water underneath her land, or water naturally flowing on, through, or along the borders of her land. A riparian right to make use of the water is not limited by priority date and it cannot be lost by non-use. Idaho law does not recognize a “riparian right” to divert and use water.

A water right under the law of the state of Idaho can be established only by appropriation, and once established, it can be lost if it is not used.