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  D e s e r t   E x p o s u r e September 2011

Humans & Nature

Water Rights and Wrongs

Myth vs. fact: Understanding the Arizona Water Settlements Act
and the future of the Gila River.

Allyson Siwik and Dutch Salmon, GCC



Water issues in the West are legally complicated, politically charged and difficult to understand. The Arizona Water Settlements Act of 2004 (AWSA) is no exception. The AWSA settled longstanding Indian water rights claims in Arizona. The Act also created the formal mechanisms by which the Secretary of Interior may deliver 14,000 acre-feet per year of additional water to New Mexico that was originally authorized by the Colorado River Project Act in 1968.

The Arizona Water Settlements Act created a mechanism by which up to 14,000 acre-feet per year could be diverted from the Gila River. (Photos by Dennis O’Keefe)

Since the AWSA was signed into law, stakeholders in southwestern New Mexico have been engaged in a planning process to reach consensus on how to utilize the benefits of the AWSA in a cost-effective way to balance historical and future demands for water against uncertain supply while also protecting the environment (see "A Free Flow of Ideas," February 2010). That's a tall order and one that requires a clear and consistent understanding of the AWSA in order for us as a community to make rational decisions about our water future.

Let's look at some of the common misconceptions about what the Act does or doesn't do for us.


Myth #1: The AWSA requires us to divert water from the Gila River in order to receive AWSA funding.


Under the AWSA, New Mexico has the choice to implement non-diversion alternatives OR to divert water from the Gila River. Funds made available through the AWSA may be used to meet water supply demands in the Southwest Planning Region of New Mexico (Catron, Luna, Hidalgo and Grant counties), either through the construction of a New Mexico Unit to increase diversion capacity, or through non-diversion water projects. New Mexico will receive a guaranteed $6.6 million a year for 10 years, beginning in 2012, that can be used for any water project that meets a water supply demand. New Mexico may also receive an additional $34-$62 million if it chooses to construct a New Mexico Unit. The maximum amount of funding available to New Mexico is $128 million (indexed for construction cost increases).


Myth #2: Gila River water is New Mexico's water and we can't let it go downstream to be used in Arizona.


The Gila River already flows into Arizona, where its waters are being used by the Gila River Indian Community downstream of the Arizona-New Mexico line. The 14,000 acre-feet of Gila River water belongs to the Gila River Indian Community. Through an "Exchange Agreement" and only by paying an "exchange cost," the AWSA provides New Mexico with the ability to divert and use this water if we choose.

The "exchange cost" will allow the Gila River Indian Community to buy their water from the Central Arizona Project (CAP) as replacement for the water that New Mexico takes out of the Gila. The going rate in 2011 for purchasing water from the CAP is $122 per acre-foot (one acre-foot is 326,000 gallons, enough water to supply a suburban US household for one year). For example, if New Mexico were to divert all of the 14,000 acre-feet of water in 2011, we would have to pay $1.7 million in exchange cost. This cost is predicted to rise 5% per year, according to the CAP.

When you factor in a 15%-30% evaporation rate from a reservoir used to store diverted water, as much as 6,000 acre-feet per year could be lost to evaporation. New Mexico would have to pay the exchange cost for that water — $732,000 at 2011 CAP costs — even though it would be lost to the atmosphere only to come down as rain in some distant locale.


Myth #3: The AWSA protects the ecology of the Gila River: We're just taking the flood flows, which don't have any noticeable impact on the Gila.


A New Mexico Unit would have to be reviewed and approved under the National Environmental Policy Act and Endangered Species Act and any other applicable environmental laws before it could move forward. A preliminary analysis that takes an "environmental flows" approach was conducted and indicates that the frequency of small floods could be reduced and occurrence of zero flow days increased as a result of a diversion. Combined with other impacts, these hydrologic alterations could adversely affect native fish and the Gila's riparian ecosystem as a whole.

The New Mexico Interstate Stream Commission (ISC) refers to a simplified Excel spreadsheet "model" it used to negotiate the terms of the AWSA back in 2003-2004 as proof that it is possible to divert 14,000 acre-feet of water per year from the Gila and not harm the ecosystem. The model assumes a minimum flow of 150 cubic feet per second (cfs) remains in the river for the ecosystem before water would be diverted. The ISC's assertion is flawed for the following reasons:

  1. There is no legally enforceable requirement under the AWSA to maintain this 150 cfs minimum flow.
  2. This analysis is more of a hydrological analysis rather than an ecological impact analysis.
  3. This arbitrary flow level does not reflect the current state of the science on how to maintain a healthy river ecosystem. "Minimum flows" is an outdated, simplistic method not supported by scientists who participated in both of the Gila Science Forums. The science has evolved to an understanding of how alterations to the hydrologic flow regime — the pattern of "peaks and valleys" of stream flow across the seasons in a year — impact riparian ecosystems.

An alternative analysis taking an "environmental flows" approach and also using the ISC's data was conducted by a member of the AWSA planning process back in 2006. This analysis indicates that flow alteration as a result of diverting 14,000 acre-feet per year according to the terms of the AWSA would consist chiefly of reduced low flows, increased occurrence of zero-flow days at the Gila Gauge, and reduced frequency of small floods.




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