Arizona's Colorado River Allocation

Colorado River water supplies are shared by seven Western states, the Federal Government, several American Indian tribes and the Republic of Mexico. Arizona obtains over forty percent of its water supply from the Colorado River for municipalities and industries, agriculture, Indian tribes and environmental purposes.

Modern use of Colorado River water for irrigation began in the late 1800s when water was diverted for use in California’s Imperial Valley. By 1901, some 100,000 acres of farmland were irrigated with Colorado River water in the Imperial Valley. Competition for Colorado River water supplies has increased steadily in response to population growth.  This competition has resulted in decades of political and legal confrontation and compromise. Even after Congress and the U.S. Supreme Court agreed to the apportionment of the river, competition continues.

Arizona has the right to the consumptive use of up to 2.8 million acre-feet of Colorado River water annually, making the river Arizona’s largest renewable water supply.  Arizona’s largest renewable water supply.  This supply is further apportioned, approximately one-half to mainstream Colorado River water users, and one-half to Central Arizona Project (CAP) water users.

Arizona's Colorado River water has a unique priority system.  Present Perfected Rights, as described in the Supreme Court Decree in Arizona v. California, are the most senior or first priority rights.  Federal Reservations and Perfected Rights established before September 30, 1968, are second priority.  Third priority water rights are held by water users who executed contracts with the United States on or before September 30, 1968.  Second and third priority rights are coequal.  Fourth priority rights are held by water users with contracts, Secretarial Reservations or other rights established with the United States after September 30, 1968.  The CAP water supply is primarily fourth priority.  Fifth priority water users have contracts for any unused Arizona entitlement water, while sixth priority water users have contracts for any surplus apportionment of water. 

CAP Priority System

Additional complexity is displayed within the four pools of CAP's water supply. Unlike the remainder of CAP water supplies in the Fourth Priority, the first pool of Indian Rights Settlement Water (for the Ak-Chin Indian Community  – 50,000 acre-feet [AF] and Salt River Pima-Maricopa Indian Community – 22,000 AF) is in the Third Priority, making it the highest priority in the CAP system. The Indian Settlement Water was obtained from the Yuma Mesa Irrigation and Drainage District (50,000 AF) and the Wellton-Mohawk Irrigation and Drainage District (22,000 AF), which are Priority 3 mainstem contractors.  After accounting for CAP delivery system loss of 5%, the 72,000 AF is reduced to 68,400 AF.

The next pool is the CAP Priority 4 water allocated to Indian and municipal and industrial (M&I) subcontractors, which have the highest co-equal priority for CAP Priority 4 deliveries.  The CAP Indian priority water totals 343,079 AF.  The M&I priority water totals 638,823 AF through 2043.  After 2043, the amount is 686,126 AF, due the conversion 47,303 AF of non-Indian agricultural (NIA) priority water to CAP M&I priority.  Thus, the total amount of CAP Indian and M&I priority is 981,902 AF through 2043. After 2043, the amount is 1,029,205 AF.

The third pool, NIA “Relinquished Water” pool (hereafter referred to as the “NIA Priority Pool”), has been allocated 364,698 AF through 2043.  In 2044, 47,303 AF converts to CAP M&I priority, leaving 317,395 AF for the NIA Pool.  This pool was created as part of the 2004 Arizona Water Settlements Act (AWSA) when the CAP non-Indian-agricultural contractors relinquished their NIA priority water subcontracts (due to its high cost) for a pool of less costly CAP excess water.

The fourth pool is the remaining CAP supply, known as the “Excess Pool.”  The priority of delivery within this pool is as follows: “Non-Indian Agriculture Settlement” water, which decreases according to the following schedule: 400,000 acre-feet through 2016; 300,000 acre-feet, from 2017 through 2023; and 225,000 acre-feet, from 2024 through 2030 (after 2030, the pool goes to zero); the Arizona Water Banking Authority (AWBA) and the Central Arizona Groundwater Replenishment District (CAGRD) replenishment reserve (they have co-equal priority) pool; and other excess water deliveries (i.e., short term contracts).   The AWBA/CAGRD and short term contracts supplies are variable because they are dependent on CAP’s annual Priority 4 supply and on the total annual demand of the CAP’s higher priority users.

In general, excess water supplies will decrease over time as existing entitlement holders increase their water demands. 

Future Steps In CAP Reallocation

The Arizona Water Settlements Act and the Arizona Water Settlement Agreement provided for the reallocation of 96,295 acre-feet of relinquished NIA priority CAP water. This water was reallocated to the Arizona Department of Water Resources (Department or ADWR) to be held in trust for further allocation by the Secretary of the Interior. The Department began offering the 96,295 acre-feet of CAP NIA Priority entitlement to existing non-Indian M&I water providers and Industrial water users in a tiered process with the first phase  in 2013. We anticipate starting the next phase of the tiered reallocation process in 2021, and if needed in 2030. The timing is intended to coincide with necessary actions required to meet requirements of the Agreement, as well as other considerations. 

On January 17, 2014, the Director of ADWR submitted a letter of recommendation on the 2013-phase of the NIA priority CAP water reallocation to the Secretary.

The Department's CAP subcontract transfer policy

Occasionally, an existing CAP Municipal/Industrial subcontract entitlement is available for transfer. ADWR has a substantive policy statement titled CAP Transfer Policy CR 6 which describes how the Department will evaluate competing applications for a CAP subcontract entitlement transfer.  As municipalities with CAP subcontracts continue to grow and utilize their full CAP subcontract entitlements, fewer transfer actions are anticipated. Here is a report on recorded CAP Subcontract transfers from 1993 to the present.

The Department's Mainstem Colorado River Transfer policy

ADWR has a substantive policy statement titled Policy and Procedure for Transferring an Entitlement of Colorado River Water. This policy statement describes how the Department will evaluate the proposed transfer of a non-Indian, mainstream Colorado River water entitlement.  In addition to the Department’s evaluation and development of a recommendation, other factors should be considered when pursuing the transfer of a mainstream Colorado River entitlement.  The transfer or lease of Indian entitlement requires Congressional authorization.  If the proposed transfer involves water associated with lands located within an irrigation district, the district must approve the transfer.  In addition, city and/or county economic impacts should be considered, and environmental compliance may be required. Here is a report on recorded Arizona Colorado River Entitlement transfers occurring from 2000 to present. There are no transfers of mainstream Colorado River entitlements that are currently being processed by the Department.