Prior appropriation

Prior appropriation water rights is the legal doctrine that the first person to take a quantity of water from a water source for "beneficial use"—agricultural, industrial or household —has the right to continue to use that quantity of water for that purpose. Subsequent users can take the remaining water for their own beneficial use provided that they do not impinge on the rights of previous users.

This doctrine developed in the western states of the United States. These water rights are different from riparian water rights, which are applied in the rest of the United States. In the western states, water supplies are very limited and must be allocated sparingly based on the productivity of its use. The right is also allotted to those who are “first in time of use.”

The appropriation doctrine originated in California around the time of the Gold Rush where miners were looking for ways to increase the amount of water available for mining operations. The 1855 California Supreme Court case of Irwin v. Phillips is what brought the water appropriation problems to light. Matthew Irwin diverted a stream for his mining operation. Shortly afterward, Robert Phillips started a mining operation downstream and eventually tried to divert the water back to its original streambed. The case was taken all the way to the California Supreme Court, which ruled in favor of the appropriation law.

The legal details vary from state to state; however, the general principle is that water rights are unconnected to land ownership, and can be sold or mortgaged like other property. These rights can be lost over time if non-use of the water source is demonstrated or if the water has not been used for a certain number of years.

There are four essential elements: intent, diversion, beneficial use, and priority. The first person to use a quantity of water from a water source for a beneficial use has the right to continue to use that quantity of water for that purpose. Subsequent users can use the remaining water for their own beneficial purposes provided that they do not impinge on the rights of previous users; this is the priority element of the doctrine. In addition to this, a user may not change the intent in which he is appropriating water such that the change hinders the use by another. These Preservation of Conditions were granted to the second user after Farmers High Line v. City of Golden (CO 1954).

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