What doctrine governs water usage in Arizona?

The doctrine that governs water usage in Arizona is the Prior Appropriation doctrine. This principle is based on the idea of "first in time, first in right," meaning that the earliest users of water have preferential rights over those who come later. In arid regions like Arizona, where water is a limited and valuable resource, this doctrine is particularly important as it establishes a clear legal framework for allocating water rights among users, such as farmers, cities, and industries.

Under the Prior Appropriation doctrine, users must demonstrate beneficial use of the water, which can include agricultural, domestic, industrial, or recreational purposes. This requirement ensures that water is not wasted and is used in ways that support the community's needs. While riparian rights apply to areas with abundant water bodies, they do not govern water allocation in Arizona, aligning the state's water regulation more closely with the realities of its climate and hydrology. Littoral rights pertain to properties adjacent to lakes or oceans, which is also not relevant to Arizona's water law. Reliction involves the gradual withdrawal of water, which can affect property boundaries but does not govern water usage rights directly.