Water Resources

City of Tempe Water Service Area - Water Resources Plan, December 2006

The City of Tempe relies on renewable and sustainable water supplies, with a diverse mix of water resources available to meet the needs of our water service area:

1. Salt River Project Water Supplies -  The Salt River Project (SRP) supplies Tempe surface water from six reservoirs on the Salt and Verde Rivers. The Salt/Verde River watershed covers an area over 13,000 square miles, from the headwaters of the Verde River in north central Arizona and the headwaters of the Salt River in the White Mountains of eastern Arizona, down to the desert in the Salt River Valley.

Established in 1903, the Salt River Valley Water Users Association (SRVWUA) is the private water association of the Salt River Project. The SRVWUA was formed by farmers and ranchers in the Salt River Valley who together pledged over 200,000 acres of their land as collateral to repay the loan for one of the first Federal Reclamation Projects: construction of the Theodore Roosevelt Dam. Roosevelt Dam, at the confluence of the Salt River and Tonto Creek 60 miles northeast of the Salt River Valley, was completed in 1911.

The second component of the Salt River Project is the Salt River Project Agricultural Improvement and Power District, which oversees the power generation side of SRP. The Power District, established in 1937, was formed as a unit of government, and as such is able to issue municipal bonds.   

Today SRP serves water to a service area of over 248,000 acres in the Salt River Valley, delivering nearly 1,000,000 acre-feet of water per year to SRP shareholder lands. The SRP water service area is approximately 88% urbanized, with about 12% of lands still used for agriculture. SRP delivers water supplies to the Cities of Chandler, Gilbert, Glendale, Mesa, Peoria, Phoenix, Tempe and Scottsdale. These communities treat SRP water supplies at their city-owned water treatment plants for delivery to SRP shareholder lands within each city.     

SRP water supplies available to Tempe are limited to use on SRP member lands in the Tempe Water Service Area. SRP also delivers surface water from the Salt and Verde Rivers appurtenant to Class A normal flow lands in Tempe. Class A lands have decreed water rights that pre-date construction of the SRP reservoir system.

These lands are entitled to receive “normal flow” surface water deliveries as determined by court decree (the 1910 Kent Decree). The amount of surface water available for use pursuant to the decree is based on the priority date of the Class A land and the amount of runoff measured on the Salt River and tributaries above the inflow to the SRP reservoir system.

SRP delivers groundwater from SRP wells pumped into canals when needed to supplement surface water supplies. SRP wells are also used to deliver groundwater directly to SRP shareholders and cities. SRP operates a network of over 240 groundwater wells across its water service area. 

Approximately 80% of lands within the Tempe Water Service Area are eligible to receive either SRP stored water or decreed normal flow water supplies. Approximately 65% of lands within the Tempe Water Service Area have entitlements to both SRP stored water and normal flow surface water supplies. 

2. Central Arizona Project Colorado River Water Supplies - The Central Arizona Project (CAP) supplies Colorado River water to the City of Tempe and other municipalities, agricultural water users and Indian communities in Central Arizona. CAP pumps Colorado River water from Lake Havasu in western Arizona and delivers it to water users in Maricopa, Pinal and Pima Counties through the 336 mile CAP canal, terminating south of Tucson.         

The seven Colorado River basin states entered into the Colorado River Compact in 1922. The Compact apportioned the use of Colorado River water among the upper and lower basin states, with the upper basin states of Colorado, Wyoming, Utah and New Mexico allocated 7.5 million acre-feet, and the lower basin states of Arizona, California and Nevada allocated 7.5 million acre-feet each year. Disputes over Arizona’s share of the lower basin apportionment delayed the adoption of the Compact by the State of Arizona until 1944. Colorado River water allocations in the lower basin:

  • Arizona has an annual allocation of 2.8 million acre-feet

  • California has an annual allocation of 4.4 million acre-feet

  • Nevada has an annual allocation of 300,000 acre-feet

  • Mexico has an annual allocation of 1.5 million acre-feet pursuant to a 1944 treaty with the United States

The Colorado River Basin Project Act of 1968 authorized construction of the CAP system to bring a portion of Arizona’s Colorado River allocation to central Arizona. In 1971, the Central Arizona Water Conservation District (CAWCD) was created to oversee construction, operation and management of the CAP system. CAWCD is a political subdivision of the State of Arizona, with 15 elected Board members. CAP delivers approximately 1.5 million acre-feet of Colorado River water to central Arizona each year. In Tempe, CAP water is used to meet water demands on lands not entitled to SRP water supplies, about 20% of all lands within the Tempe Water Service Area.

3.Modified Roosevelt Dam New Conservation Space (NCS) Water Supplies-  Authorization of the Central Arizona Project included a regulatory storage component and upgrades to existing dams and infrastructure. One of the early sites proposed for a regulatory storage reservoir was the Orme Dam, proposed to be constructed at the confluence of the Salt and Verde Rivers. A Presidential review of water projects in 1977 recommended that Orme Dam and several other dams be eliminated, and replaced by alternative dam locations. In 1981, the Secretary of the Interior identified a proposed alternative action, Plan 6. Plan 6 included construction of the New Waddell Dam on the Agua Fria River for regulatory storage of CAP water, the expansion of Roosevelt Dam, and a new dam on the Verde River, Cliff Dam. Cliff Dam was later deleted from the plan, but New Waddell Dam and Modified Roosevelt Dam were completed pursuant to Plan 6.

The City of Tempe funded and secured rights to 5% of the new water conservation capacity created when Roosevelt Dam was expanded in the mid-1990s, approximately 13,500 acre-feet of surface water storage capacity. Other cities that participated in the Plan 6 New Conservation Space (NCS) agreement include the Cities of Phoenix, Mesa, Scottsdale, Chandler and Glendale.  

Roosevelt Dam NCS water can be used for any beneficial uses within the Plan 6 cities’ water service areas. Tempe plans to use NCS water supplies to meet water demand on lands not entitled to SRP water supplies, similar to the use of CAP water supplies in Tempe.

4. Groundwater - The Arizona State Legislature passed a comprehensive groundwater bill in 1980, which was signed into law by then Governor Bruce Babbitt. The 1980 Groundwater Management Act was created to address the use of groundwater and groundwater overdraft in the most populous areas of the State. These areas are referred to as Active Management Areas (AMAs). There are five AMAs in Arizona: Phoenix, Tucson, Pinal, Prescott, and Santa Cruz. Groundwater users in AMAs are regulated, with limits on how much groundwater can be used in any year. The primary goal of the AMAs is to achieve safe-yield groundwater use by 2025, where groundwater withdrawal and use is balanced by natural and artificial groundwater recharge. The Arizona Department of Water Resources (ADWR) administers programs in each AMA that encourage the use of renewable water supplies and promote water conservation among all water users.  

Tempe can withdraw a limited amount of safe-yield groundwater supplies from its wells each year. Water stored in groundwater aquifers through groundwater recharge projects can also be recovered through city wells that are permitted as recovery wells. The use of groundwater from Tempe’s municipal production wells over the last decade has ranged from less than 1% to about 7% of Tempe’s total municipal water use in a normal year. During periods of prolonged drought, with reductions in available surface water supplies, Tempe’s use of groundwater may be increased within allowable limits until watershed conditions improve. The ADWR Assured Water Supply Rules allow for drought exemption groundwater pumping only during periods when normal surface water supply allocations have been reduced due to drought conditions.

5. Reclaimed Water Supplies - Wastewater collected throughout the Tempe water service area is treated at the regional 91st Avenue Wastewater Treatment Plant (WWTP) in Phoenix, or locally at the Kyrene Water Reclamation Facility. The City of Phoenix and its Sub-regional Operating Group (SROG) partners Glendale, Mesa, Scottsdale and Tempe jointly own the 91st Avenue WWTP and transmission facilities. The plant is operated by the City of Phoenix for the partnership. Effluent, or reclaimed water, produced at the 91st Avenue WWTP is used for cooling water at the Palo Verde Nuclear Generating Station west of Phoenix, for irrigation uses by the Buckeye Irrigation Company, and for a riparian habitat project: the Tres Rios Constructed Wetlands Demonstration Project. In the future, reclaimed water from this facility may be used for groundwater recharge and storage credits at the Agua Fria Linear Recharge Project and for riparian habitat at the full scale Tres Rios wetland project.           

Reclaimed water produced at the Tempe Kyrene Water Reclamation Facility (KWRF) is currently used to supply water for irrigation use at the Tempe Ken McDonald Golf Course, industrial water uses and cooling water at the SRP Kyrene Electric Generating Station, and for groundwater aquifer recharge. The Tempe Water Utilities Department has just completed an expansion and technology upgrade construction project at the KWRF. The reclaimed water treatment capacity is now rated at 9.0 MGD. Future uses of this additional reclaimed water supply in Tempe may include supplemental supply for the Tempe Town Lake, additional irrigation reuse sites, and expanded groundwater recharge projects. When reclaimed water is used on lands eligible for SRP water, the SRP water saved is accrued as exchange credits for Tempe.

6. Aquifer Storage Credits (Long Term Storage Credits) -  Tempe has water storage permits and/or underground storage facility permits for several recharge projects and groundwater savings programs that provide for the recharge of groundwater aquifers using Tempe’s CAP water, NCS water, or reclaimed water supplies. The water that is recharged establishes aquifer “credits” that can be withdrawn at a later date through recovery wells, especially during times of drought. These projects include:

  • Granite Reef Underground Storage Project (GRUSP)

  • Tempe Ken McDonald Golf Course Groundwater Recharge Project

  • Salt River Project Groundwater Savings Facility

  • New Magma Irrigation & Drainage District (NMIDD) Groundwater Savings Facility

Tempe’s storage capacity at GRUSP is used primarily for the storage of CAP or NCS surface water in the East Salt River Valley groundwater sub-basin for long-term aquifer storage credits. Short term monthly storage and recovery can also be done using SRP surface water supplies. The Tempe Ken McDonald Golf Course Recharge Project formerly used a dry well, or a vadose zone recharge well, to recharge the upper alluvial aquifer using reclaimed water from the Kyrene Reclamation Facility. The Water Utilities Department is planning to increase recharge capacity and upgrade the recharge technology at this site by converting to an aquifer storage and recovery (ASR) injection well system that will be used for both recharge storage and recovery of water from the aquifer for irrigation use at the golf course.

Groundwater savings facility programs are considered “in lieu” recharge projects. Tempe has partnered with SRP and NMIDD in programs to reduce their groundwater pumping through the purchase and direct use of excess CAP water instead of using local groundwater supplies. The groundwater saved accrues as long-term storage credits to Tempe for future recovery and use.

The SROG city partners at the 91st Avenue Wastewater Treatment Plant are in the planning phase of a recharge project in the west Salt River Valley. The Agua Fria Linear Recharge Project will recharge reclaimed water from the 91st Avenue WWTP along the Agua Fria River channel to replenish the aquifer in an area where groundwater levels have fallen over the past several decades. The reclaimed water stored will establish long-term storage credits for the SROG partner cities, and perhaps water exchange opportunities for the SROG cities in the east Salt River Valley.

Find out more information about Tempe's water supplies by clicking on the link to Tempe's Water Resource Plan, or for more information please contact Eric Kamienski 480-350-2608.