Restricting water rights usage during summer months in Phoenix

When water supplies are inadequate, how should available supplies be allocated? Under the prior appropriation doctrine, temporal priority controlled with the highest priority going to the most senior water user. The concept of temporal priority has been utilized in eastern states, but not as the sole determinant of priority in times of shortage. The emerging eastern approach as seen in the Model Code has been to list a series of factors that should be considered in determining whether a permit should be issued. The Model Code allows a water use permit to be issued "only upon determining that: (a) the proposed use is reasonable; (b) the proposed withdrawal, in combination with other relevant withdrawals, will not exceed the safe yield of the water source; (c) the proposed withdrawal and use are consistent with any applicable comprehensive water allocation plan and drought management strategies; (d) both the applicant's existing water withdrawals and use, if any, and the proposed withdrawal and use incorporate a reasonable plan for conservation;

and (e) the proposed withdrawal and use will be consistent with the provisions of this Code and any order, permit term or condition, and regulation made pursuant to this Code or any other statute pertaining to the use of water" (§6R-3-01). The factors to be considered in determining whether a use is "reasonable" include impacts on both existing water users and on the public interest (§6R 3-02). In times of shortage, the first priority goes to "direct human consumption or sanitation," the second priority going to agriculture, and the third priority going to "other uses in such a manner as to maximize employment and economic benefits within the overall goal of sustainable development" (§6R-3-4). Similar legislation has been enacted in at least 12 eastern states.

As eastern states move toward a balance between temporal priority and the public interest, the western states, either by statute or case law, are moving in the same direction. Virtually all of the western states now require consideration of the public interest when an appropriation is initiated (Johnson and DuMars, 1989).

In essence, eastern and western states are moving toward a concept of "equitable priority" that balances impacts on existing water users (temporal priority) with public interest consideration.

Should state laws protect instream flows? Many of the prior appropriation doctrine states answered this question in the negative, requiring a diversion of water from a watercourse before a right to the water could be established. In the historically riparian doctrine states, the English common law concept of "natural flow" was replaced by the "reasonable use" requirement in order to encourage economic development. Absent state legislation, however, the definition of "reasonable use" did not include instream uses.

There has been increasing recognition in both eastern and western states of the importance of protecting instream flows. Navigation, public water supply, sanitation, and fish/wildlife purposes have been recognized as requiring minimum streamflows. Recreational, aesthetic, and ecological uses now are being recognized as equally important water uses. In the prior appropriation doctrine ...