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Active Management Area Water Supply - Surface Water

Physical Supplies

In addition to CAP water, other major sources of surface water in the planning area are the Salt and Verde rivers, which supply the Phoenix AMA and the Gila River; supplying the Phoenix and Pinal AMAs.

The dams and reservoirs on the Salt and Verde rivers, located in the Central Highlands Planning Area and operated by the Salt River Valley Water Users Association, or SRP, store and release water for the benefit of agricultural, municipal and industrial users in the Phoenix metropolitan area. SRP was established in 1903 as the nation’s first multipurpose reclamation project.  It is the nation’s third largest public power utility and one of the state’s largest water suppliers.  Working with other agencies, the SRP manages or assists with the management of seven dams; the six shown in Figure 8.0-17. Water stored in C.C. Cragin Dam, located in the Eastern Plateau Planning Area, may be pumped into the East Verde River for use in the Phoenix AMA.  This reservoir system is utilized in conjunction with about 250 groundwater wells to provide water through 131 miles of canal to a 2,900 square mile service area that delivers more than 1.0 maf of water annually to its customers.  The service area encompasses portions of the East Salt River Valley and West Salt River Valley sub-basins in the Phoenix AMA, including portions of Chandler, Gilbert Glendale, Mesa, Peoria, Phoenix, Scottsdale, Tempe and Tolleson. (SRP, 2008)  Historically, SRP water was primarily used for agricultural irrigation; now a large portion of the project’s service area is urbanized. In addition to SRP, the Roosevelt Water Conservation District and the Buckeye Water Conservation District use surface water from the Salt and Verde rivers.

The total capacity of the SRP reservoir system and maxiumum storage elevations are shown in Figure 8.0-17. Capacity on the Salt River system is over 2.0 maf, primarily at Roosevelt Lake. The capacity of the reservoir was increased by 20% with completion of a 77-foot dam heightening project in 1996.  The new conservation space between 2,151 feet and the pre-modification elevation of 2,136 feet is available to six valley cities.  Flood control storage is between elevations 2,151 and 2,175 feet.  The space between 2,175 feet and the maximum storage elevation of 2,218 feet is called safety of dam space.  By comparison, the Verde River system reservoirs are considerably smaller with a storage capacity of over 302,000 acre-feet and average annual inflows exceeding storage capacity.  Consequently, the Verde River reservoirs are managed to minimize the potential for spill during the winter months, with releases of water during the fall, winter and spring (Ester and Reigle, 2001). 

Figure 8.0-18 Profile View of SRP Salt and Verde Reservoir System

SRP reservoir system

Graphic courtesy of SRP

As shown in Figure 8.0-18, storage in SRP dams fluctuates as water is collected and then released to meet water demands. The impact of drought conditions can be observed during 1989 and again beginning in the mid 1990s. Substantial storage recovery is seen in 2005 and 2008 following wet winters.  As of February 1, 2010, storage in the Salt River system was 95% of capacity after a series of strong winter storms. Just a month before, on January 1, 2010, storage was 79% of capacity.  Storage volumes in the Verde River reservoirs, particularly Horseshoe Lake, have been reduced to almost zero at times during recent drought years.  On June 1, 2007, storage in the total Verde system had been reduced to 27% of capacity but by June 1, 2009 had increased to 63% of capacity. By February 1, 2010, the storage volume had increased to 83% of capacity. (CAP, 2010)

Figure 8.0-18

Figure 8.0-18 Water Stored on May 1st in SRP Reservoirs on the Verde and Salt Rivers, 1980-2009

Water from the Gila River is used primarily for agricultural irrigation. The primary storage and flood control facility on the Gila River is Coolidge Dam located in the Southeastern Arizona Planning Area about 30 miles southeast of Globe.  The dam is part of the San Carlos Irrigation Project (SCIP).  Water is diverted in the Pinal AMA for the SCIP at Ashurst-Hayden Diversion Dam located 12 miles east of Florence.  The dam, completed in 1922, consists of diversion works and is not a storage or flood control facility.  Diverted water is conveyed to the San Carlos Irrigation and Drainage District (SCIDD), located in the Pinal AMA, consisting of approximately 200 miles of unlined main and lateral canals and 40 miles of canals owned jointly with the SCIP (ADWR, 1998b).  In addition to agricultural uses, SCIDD delivers Gila River water mixed with groundwater for landscape irrigation to subdivisions, schools and parks in Casa Grande, Coolidge and Florence (ADWR, 1999b). The SCIP also delivers Gila River water to tribal lands within the Gila River Indian Community located in the Phoenix and Pinal AMAs.  The Buckeye Water Conservation and Drainage District in the West Salt River Sub-basin of the Phoenix AMA also uses Gila River water as part of its water supply.

Lake Pleasant

Lake Pleasant. Water is delivered to the MWD service area via the 33-mile Beardsley Canal from Lake Pleasant.

Maricopa Water District (MWD) in the West Salt River Valley Sub-basin uses a combination of CAP and Agua Fria River water stored in Lake Pleasant behind New Waddell Dam.  This water is delivered to the MWD service area via the 33-mile Beardsley Canal.  MWD owned and operated Waddell Dam, the original storage and flood control structure on the Agua Fria River, which was later inundated by the enlarged Lake Pleasant. (ADWR, 1998b)

A few other sources of surface water are utilized in the planning area. When available, Santa Cruz River water is diverted for agricultural irrigation by some growers in the Central Arizona Irrigation and Drainage District in the Eloy Sub-basin of the Pinal AMA (ADWR 1998b). In the Tucson AMA, surface water diverted from Cienega Creek is used for turf irrigation at Del Lago Golf Course at Vail and springs are the water supply for the community of Summerhaven, located in the Santa Catalina Mountains.

In the Prescott AMA, the City of Prescott has acquired rights to water stored in Watson Lake and Willow Creek reservoirs from the Chino Valley Irrigation District (CVID). Under an agreement with CVID, the City maintains the lakes for recreational purposes and releases approximately 1,500 AFA for recharge, which it recovers on an annual basis. In return the City provides up to 1,500 acre-feet annually of recovered effluent credits to CVID members for irrigation. While the City also holds rights to water stored in Lynx and Upper Goldwater reservoirs, this water is not used as a water supply.

Legal Availability

State statutes, ongoing water rights adjudications, court decrees and settlements all affect the use of surface water supplies in the planning area and are discussed below.  In addition, environmental laws, instream flow rights and environmental protection designations assign surface water supplies to environmental purposes.  These are discussed further in Section 8.0-4 and include the Endangered Species Act and associated habitat conservation plans.

Rights to surface water in Arizona are subject to the doctrine of prior appropriation, which is based on the tenet “first in time, first in right”. This means that the person who first put the water to a beneficial use acquires a right that is superior to all other surface water rights with a later priority date. Under the Public Water Code, beneficial use is the basis, measure and limit to the use of water. The surface water rights system is further discussed in a later sub-section.

Arizona has two general stream adjudications in progress to determine the nature, extent and priority of water rights across the entire Gila River and Little Colorado River systems. The adjudications will recognize existing water right decrees and settlements (discussed below) and adjudicate all remaining water rights claims in the river systems. Pertinent to the AMA Planning Area, the Gila River Adjudication is being conducted in the Superior Court of Arizona in Maricopa County. The Gila Adjudication was initiated by petitions filed by several parties in the 1970’s, including Salt River Project, Phelps Dodge Corporation and the Buckeye Irrigation Company. The petitions were consolidated in 1981 into a single proceeding. The Gila Adjudication includes seven adjudication watersheds - Upper Salt, San Pedro, Agua Fria, Upper Gila, Lower Gila, Verde, and Upper Santa Cruz. Most of the Upper Santa Cruz and parts of the Agua Fria, Lower Gila, Upper Salt and Verde adjudication watersheds are within the planning area boundaries. These watersheds do not coincide with the 6-digit HUC watersheds discussed previously and shown in Figure 8.0-5. The entire Gila Adjudication includes over 24,000 parties.

Court determinations that currently affect the distribution of surface water supplies in the planning area including the Kent and Benson-Allison decrees. The Kent Decree (1910) determined that almost 240,000 irrigable acres in the Salt River Valley had a right to water diverted from the Salt and Verde rivers for agricultural purposes and determined which lands were entitled to receive water from Roosevelt Lake.  The Salt River Valley Water Users Association is responsible for the proper accounting and delivery of water pursuant to the decree. The Kent Decree also increased and decreed Salt River Indian Reservation rights and recognized Fort McDowell Indian Reservation water users. Further, it established the concept of normal flow rights whereby the land on which water was first used had first right to water normally flowing in the river, and water other than normal flow (stored and developed water) was to be shared equally on lands within a water users association. The Benson-Allison Decree (1917) addressed irrigation lands in the Phoenix AMA that are entitled to divert water from the Salt, Agua Fria and Gila rivers. Most of the rights in a prior decree, the Haggard Decree, were encompassed in this decree.

The 2004 Arizona Water Settlements Act (Act) allocates over 700,000 AFA to the Gila River Indian Community (GRIC) and the Tohono O’odham Nation (TON) (Bark, 2009). Title I of the Act settled the Central Arizona Project debt repayment obligation at $1.65 billion and reallocated CAP water between federal (Indian) and state (non-Indian) uses including the reallocation of high priority uncontracted CAP water to cities.

Title II of the Act allocates 653,500 AFA to the GRIC who have signed a number of water leases and exchanges that provide water to municipalities. The GRIC water entitlement includes water from the CAP, SRP, groundwater and a reclaimed water exchange with the cities of Mesa and Chandler. This exchange provides treated effluent for part of the tribe’s CAP water on a 5 to 4 ratio and allows the cities to use potable water for municipal uses and the tribe receives treated effluent for agricultural use. (Smith and Colby, 2007)

In addition, Title II includes agreements by parties not to drill new wells near the reservation boundary, or to limit pumping. (ADWR, 2006b)

C.C. Cragin Reservoir, formerly referred to as Blue Ridge Reservoir, located approximately 25 miles north of Payson, was acquired by SRP from Phelps Dodge Corporation in February 2005 as part of the Arizona Water Settlement Act.  The reservoir satisfies obligations to the Gila River Indian Community in the Phoenix AMA and will be used to supplement SRP’s water supply via diversions from the reservoir into the East Verde River.  The Act also allocated 3,500 AFA from the reservoir to northern Gila County, of which 3,000 AFA will be used by Payson. (SRP, 2007)

Title III of the Act, the Southern Arizona Water Rights Settlement Act (SAWRSA) settled litigation concerning the 1982 SAWRSA settlement. It allocated 79,200 acre-feet of water per year to the San Xavier and eastern Schuk Toak Districts of the TON within the Tucson AMA. The allocated rights include: 13,200 AFA of “underground water”; 37,800 AFA of currently contracted CAP Indian Priority Water; and 28,200 AFA of new CAP Non-Indian Agricultural Priority Water. The Act also allows limited off-reservation water leasing. Implementation of SAWRSA includes a special management zone adjacent to and outside the reservation boundaries, the San Xavier Buffer Zone, in which the drilling of non-exempt new wells is restricted.

Surface Water Right System

The legal framework and process under which surface water right filings are administered is complex.  Each type of surface water right filing is assigned a unique number with a prefix as explained in Appendix C and listed in Table 8.0-8. All parties who use water or claim to have a water right within the two adjudication areas are required to file a statement of claimant or SOC (39) in the adjudication, or risk loss of their right.  This includes reserved water rights for public lands and Indian reservations, of which only some have been quantified or prioritized. Other surface water right filings are discussed below.

Table 8.0-8 Inventory of surface water right and adjudication filings in the AMA Planning Area (1)

Table 8.0-8

A Certificate of Water Right (CWR) may be issued if the terms of the permit to appropriate water (3R, 4A or 33, and in certain cases, 38) are met.  CWRs retain the original permit application number.  Statements of claim of right to use public waters (36) have also been filed, but their filing does not in itself create a water right. Surface water rights can also be determined through judicial action in state or federal court in which the court process establishes or confirms the validity of the rights and claims and ranks them according to priority.  Court decreed rights are considered the most certain surface water right.

Table 8.0-8 summarizes the number of surface water right and adjudication filings in the planning area. The methodology used to query the Department’s surface water right and SOC registries is described in Appendix C.  Of the 35,417 filings that specify surface water diversion points and places of use in the planning area, 3,184 CWRs have been issued to date. Figure 8.0-19 shows the location of surface water diversion points listed in the Department’s surface water rights registry. The numerous points reflect the large number of stockponds and reservoirs that have been constructed in the planning area as well as diversions from streams and springs. Locations of registered wells, many of which are referenced as the basis of claim in SOCs are also shown in Figure 8.0-19.

Results from the Department’s investigation of surface water right and adjudication filings are presented in Hydrographic Survey Reports (HSRs) and other adjudications-related reports. Within the AMA Planning Area, two preliminary HSRs were published for the Gila River Indian Reservation (1996 and 1999) and one draft HSR for the Upper Salt River (1992). Technical assessments of water right settlements for several Indian tribes including the Salt River Pima-Maricopa Indian Community (1991); Fort McDowell Indian Community (1993); San Carlos Apache Tribe (1999); Gila River Indian Community (2006); and Tohono O’odham Nation (2006).

The location of surface water resources are shown on surface water condition maps and maps showing perennial and intermittent streams and major springs for each basin in sections 8.1-8.5.  Tables  also  list data on streamflow, flood ALERT equipment, reservoirs, stockponds and springs in the sections for each basin.



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