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Active Management Area Water Supply - Central Arizona Project Water

Water supplies in the AMA Planning Area include Central Arizona Project (CAP) water, surface water, groundwater and effluent.  As shown in Figure 8.0-15, on average more than half of the annual water demand in the planning area from 2001-2005 was met with non-groundwater supplies. These non-groundwater or renewable supplies are primarily comprised of CAP water and surface water diverted from the Salt, Verde, Gila, Agua Fria or Santa Cruz rivers. Effluent is a smaller but growing non-groundwater source used in the planning area.

Non-groundwater supplies were the primary water supply in the Pinal and Phoenix AMAs during 2001-2005. In the Pinal AMA, 53% of the average annual water demand between 2001-2005 was met with a non-groundwater source and 47% of the demand was met with groundwater. The Phoenix AMA also relies heavily on non-groundwater sources; 64% of the average annual demand in 2001-2005 was met with non-groundwater sources and 36% of its demand was met with groundwater. (See Figure 8.0-20)

Figure 8.0-15 Water Supply Utilized in the AMA Planning Area

Figure 8.0-15

During 2001-2005 the Prescott AMA used primarily groundwater supplies with approximately 19% of demand met by effluent and surface water. The Santa Cruz AMA uses a combination of groundwater and surface water from the younger alluvium that is withdrawn from wells and collectively considered groundwater.  Between 2001 and 2005, the Tucson AMA used approximately 74% groundwater and 26% non-groundwater supplies to meet demands. However, the percentage of non-groundwater sources, primarily CAP, used in the Tucson AMA has increased rapidly since 2001 due to increased recharge and recovery capacity in the municipal sector.

CAP Map

Figure 8.0-16 Central Arizona Project System Map

Image courtesy of CAP

Central Arizona Project Water

The primary non-groundwater supply in the planning area is CAP water. The CAP was constructed to annually deliver 1.5 maf of Arizona’s allocation of Colorado River water to Maricopa, Pima and Pinal and counties through a series of canals and pumping stations (Figure 8.0-16).  The delivery system is 336 miles long and lifts Colorado River water 2,400 feet to its terminus just south of the City of Tucson. Water is withdrawn at Lake Havasu at the Mark Wilmer Pumping Plant. It then crosses the Parker, Ranegras Plain and Harquahala basins in the Lower Colorado River Planning Area via the Hayden-Rhodes Aqueduct to the CAP service area in central and southern Arizona.

 

The CAP canal enters the planning area on the western side of the Phoenix AMA and runs toward the east and southeast across much of the AMA. A significant portion of CAP water is stored in Lake Pleasant behind New Waddell Dam, completed in 1992, at the northern edge of the Phoenix AMA.  It then travels in a southerly direction and enters the Pinal AMA north of Florence, crosses the northeastern portion of the AMA and enters the Tucson AMA near Picacho Peak. The CAP canal terminates at Pima Mine Road in the Tucson AMA just south of the San Xavier District of the Tohono O’odham Nation. Turnouts from the CAP aqueduct connect it to municipal water treatment plants and irrigation district canals for distribution. CAP water is used both directly and indirectly through the Department’s recharge program (described below) in the Phoenix, Pinal and Tucson AMAs. CAP water was first used in the planning area in 1985.

There are three main CAP contract categories: non-Indian municipal and industrial (M&I), non-Indian agricultural and Indian.  Almost all non-Indian agricultural subcontracts have been declined or terminated and CAP water is used pursuant to the Department’s recharge program.  The status of CAP subcontracts as of October, 2009 is found in Appendix B.  According to the status report, subcontract totals were:

M&I Subcontracts                        620,678 acre-feet

Indian Contracts                          555,806 acre-feet

Non-Indian Agricultural

Subcontracts                                9,026 acre-feet

Currently Uncontracted

Water                                           155,787 acre-feet

Other Project Water

Under Contract                             73,703 acre-feet

Avra Valley Recharge

Recharge basins in Avra Valley, Tucson AMA

To encourage the direct use of renewable water supplies, the recharge program restricts the type of water that may be stored long-term to renewable water supplies that cannot be used directly.  Persons who wish to store water through the recharge program must apply to the Department for permits.  There are two types of facilities and associated permits; Underground Storage Facility (USF) Permits and Groundwater Savings Facility (GSF) Permits. In addition, a Water Storage (WS) Permit (A.R.S. § 45-831.01) allows the permit holder to store water at a USF or a GSF and a Recovery Well (RW) Permit (A.R.S. § 45-834.01) allows the permit holder to recover long-term storage credits or to recover stored water annually.

Some CAP water use on non-Indian agricultural land is pursuant to GSF Permits (A.R.S. § 45-812.01), which allows the permit holder to deliver a renewable water supply, called “in lieu” water, to a recipient (farm) who agrees to replace groundwater pumping with in lieu water, thus creating a groundwater savings.  The permit holder accrues recharge credits which can be recovered later from a well elsewhere in the AMA (or INA).  When withdrawn, the water retains the character of the water that was recharged at the GSF.

A USF Permit (A.R.S. § 45-811.01) allows the permit holder to operate a facility that stores water in the aquifer in one of two ways.  A constructed underground storage permit allows water to be stored by using some type of constructed device, such as an injection well or percolation basin.  A managed underground storage facility permit allows water to be discharged to a naturally water-transmissive area such as a streambed where the water percolates into the aquifer without the assistance of a constructed device. Not all the water stored at a USF is recoverable.  The recharge statutes require that a certain percentage of the recharged volume be made non-recoverable to benefit the aquifer. These non-recoverable volumes are called cuts to the aquifer. CAP water stored at constructed facilities carries a 5% cut to the aquifer; effluent stored at constructed facilities carries no cut to the aquifer; and effluent stored at managed facilities carries a 50% cut to the aquifer.

Most of the water delivered to recharge facilities in the AMA Planning Area is CAP water with lesser amounts of effluent and surface water.  In 2005, over 423,000 acre-feet of CAP water, 91,600 acre-feet of effluent and 11,400 acre-feet of surface water were delivered to USFs and GSFs, for a total of over 526,000 acre-feet delivered. By the end of 2008, more than 3.3 maf of long term storage credits had been accrued in the AMA Planning Area.  The location of GSF and USF sites and facility information are shown on maps and tables in the groundwater conditions section for each AMA.

 

 

water drop  Continue to Section 8.0.5  Water Supply - Surface Water

 

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