A History of Service

From the early Hohokam to the first settlers, Salt River Project’s (SRP) history is unique. Read below to see how an idea for a dam became the nation’s third largest public power utility and one of Arizona’s largest water suppliers.

300 - 1450

Clay potteryThe Hohokam build 500 miles of irrigation ditches with stone and wooden tools and then inexplicably vanish. Their system served as many as 50,000 people and set the groundwork for today’s canal system.

  • 1860 - 1880

    Swilling Mining and agricultural development in Arizona increases with an influx of settlers. Among them is John W. "Jack" Swilling who is inspired by the Hohokam’s ancient canal system and launches the Swilling Irrigating Canal Company.
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    The Swilling Irrigating Canal Company digs the Salt River Valley Canal in 1867. These revitalized irrigation systems entice more people to settle in the area.

  • 1890s

    Drought threatens life in the Valley despite an advanced irrigation system and settlers search for a reliable water source. Tonto Basin is identified as an ideal location for a dam, but financing to build it proves difficult to secure. Meanwhile, a national movement grows for federal financing of water reclamation projects.

  • 1902

    The National Reclamation Act is signed into law by visionary president Theodore Roosevelt. Water reclamation projects are now possible through government financing. Drought continues in the Salt River Valley and a reliable water supply is desperately needed.

  • 1903

    1903 pledge button Ranchers and farmers pledged their own land as collateral in order to obtain a loan through the National Reclamation Act to build a dam at the Tonto Basin site. The group forms the Salt River Valley Water Users’ Association.

  • 1906


    On Sept. 20 the U.S. Reclamation Service places the six-ton cornerstone of Theodore Roosevelt Dam at the Tonto dam site. Stones for the dam are cut out of the canyon walls and set in cement manufactured at the site. Round the clock work is interrupted by several powerful floods. In order to meet the challenges of the remote location, a hydroelectric generator is built at the site to facilitate construction of the dam.

  • 1909

    Excess power from Theodore Roosevelt Dam is delivered to irrigation pumps and other customers in the Salt River Valley, thus establishing hydropower as a "paying partner" for the water reclamation project.

  • 1910

    Kent Decree

    More than 4,500 landowners are made party to the lawsuit Hurley vs. Abbot in order to settle water rights in the Valley. Presiding judge Edward H. Kent's decision, later called the Kent Decree, establishes how much water different areas of land will receive from the Salt and Verde rivers.

  • 1911

    Former President Theodore Roosevelt arrives in Arizona to dedicate Theodore Roosevelt Dam on March 18, 1911. In his speech, Roosevelt names the National Reclamation Act and the Panama Canal as two of the greatest accomplishments of his administration.
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    At the time of the dedication, Roosevelt Lake is less than half full, but contains more than 500,000 acre-feet of water and reaches 160 feet up the dam. It is enough water to sustain the Salt River Valley with two full years of irrigation, even if there were no further inflow.

  • 1912

    Hydropower continues to be key and contracts for supplying power to the mining industry, including one with the Inspiration Consolidating Copper Company of Miami, ensure the vitality of SRP’s electric system.

  • 1917

    Water Temple The Salt River Valley Water Users' Association (Association), which acted as a liaison to the U.S. Reclamation Service, receives operational control of SRP's water and power facilities.
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    In the Association's contract with the federal government, the United States retains title to the dams, canals and hydropower plants, and SRP remains a federal reclamation project and is able to reinvest power revenues into the project. SRP's headquarters are located at Van Buren Street and 2nd Avenue in Phoenix.

  • 1920

    SRP shareholders construct drains and install pumps to remove rising groundwater. An earlier study had shown that the water table was rising at a rate of 1.5 feet per year resulting in waterlogged soil. This increased ground water left behind salt deposits rendering the land useless.

  • 1922

    CC Cragin and JR ReidFurther advancing the "paying partnership" of power and water, SRP's General Superintendent C.C. Cragin designs a plan to finance and build three additional dams along the Salt River to increase hydroelectric generating capabilities. The dams included Mormon Flat Dam in 1925, Horse Mesa Dam in 1927, and Stewart Mountain Dam in 1930.

  • 1928

    Approximately 1,000 shareholders request electric farm service, so SRP embarks on an effort to extend electricity service to a growing residential and rural customer base. SRP's effort precedes the New Deal rural electrification project by 10 years.

  • 1935-1938

    In an effort to supplement its workforce during the Depression, SRP contracts with the Civilian Conservation Corps (CCC) to conduct maintenance and construction work on the canal system. In less than three years, men from the CCC complete over 700 separate jobs working with SRP and for the Valley community.
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    The CCC crews projects included: building fences, creating trails for trucks, constructing levees or dikes, clearing laterals, lining and piping waterways, or upgrading water control structures with stone masonry or rubble lining.

  • 1937

    Maricopa County authorizes the formation of the second part of SRP, the Salt River Project Agricultural Improvement and Power District. The District is formed as a political subdivision of the state of Arizona.
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    The District is able to issue municipal bonds and proceeds from these bonds are used to redeem outstanding higher-interest bonds, thus assuring the financial health of SRP during the Depression and into the future.

  • 1939

    SRP receives approval to dam the Verde River through the construction of Bartlett Dam. The dam is erected in 1,000 days and completed in 1939. Bartlett Dam is the first multiple-arch dam the Bureau of Reclamation constructs in the nation.
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    The new dam results in improved water supplies, while simultaneously providing much needed labor opportunities for unemployed Arizonans.

  • 1941-1945

    During WWII, SRP receives help from the local prisoner of war camps in the Salt River Valley. German and Italian POWs work on SRP's water transmission and distribution system.

  • 1946

    SRP and Phelps Dodge negotiate the building of Horseshoe Dam, the second dam on the Verde River and the sixth storage dam in the water transmission and distribution system.
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    The Phelps Dodge Corporation pays for the dam with financing from the federal Defense Plant Corporation in order to supply enough water to Phelps Dodge copper mines to meet WWII production needs.

  • 1949

    The District, which was established in 1937, becomes the entity responsible for the operation and maintenance of the power system. The Association continues to operate and maintain the water transmission and distribution system.

  • 1952

    After WWII, SRP enters into contracts with the cities to deliver water to the rapidly urbanizing Salt River Valley. The first domestic water agreement is with the City of Phoenix in 1952.
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    Under these contracts, the cities are able to divert water from SRP canals at selected sites in order to deliver domestic water to SRP lands within their municipal boundaries. These contracts provide a stable water supply to the cities as SRP's service territory transitions from predominately agricultural to urban users.

  • 1952-1954

    During the post-WWII era, SRP builds three steam-generating stations in the Phoenix metropolitan area to keep pace with growth. The first facility is the Kyrene Generating Station built between 1952 and 1954. The other generating stations include Agua Fria (1957-1961) and Santan (1972-1975).

  • 1955

    The original $10.3 million debt on Theodore Roosevelt Dam and associated works are repaid to the federal government.

  • 1960

    SRP partners with other utility companies to coordinate the development of a regional power system that includes power plants and miles of long-distance transmission lines.

  • 1961

    The Valley continues to expand at a rapid pace, resulting in SRP's residential customer base doubling between 1956 and 1961. In October, SRP President Vic Corbell personally installs the 100,000th meter at the home of the Spencer family in Glendale.

  • 1965

    SRP launches new Community Styling program to better integrate its facilities into the surrounding community. The effort continues today and is now part of the SRP Municipal Aesthetics Program.

  • 1968

    President Lyndon B. Johnson signs the 1968 Colorado River Basin Project Act, which authorizes the construction of the Central Arizona Project (CAP). CAP is another major water construction and management project in Arizona and SRP lobbied heavily for its passage.

  • 1969

    The growth of the Valley during the 1960's resulted in SRP expanding underground distribution lines from two miles in 1956 to 403 miles by the end of 1960's. The increase in infrastructure was matched by SRP's concern for the environment. The first formal environmental study is completed in 1969 for Navajo Generating Station.

  • 1974

    The first of three Navajo Generating Station (NGS) units are completed followed by the second and third units in 1975 and 1976.
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    NGS in Page, Arizona is the biggest construction project SRP has ever attempted for a consortium of owners. Built on land within the Navajo Indian Reservation, the project launches a long, favorable and educational relationship between SRP and the Navajo Nation.

  • 1978

    Cornerstone The Reclamation Safety of Dams Act is passed authorizing work at 17 Western reclamation dams to bring them up to state-of-the-art safety standards.
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    This Act and a reauthorization in 1984 eventually lead to funding of more than $400 million in improvements at Stewart Mountain and Theodore Roosevelt dams on the Salt River, and Bartlett and Horseshoe dams on the Verde River.

  • 1979

    The Coronado Generating Station Unit One is completed near St. Johns, Arizona.

  • 1984

    For the first time in its history, SRP's urban water use surpasses agricultural use, with 55 percent of its water deliveries going to urban areas and 45 percent of deliveries going to agricultural customers.

  • 1986

    Roosevelt Dam's height is increased by 77 feet and new spillways added. These efforts increase water storage capacity, add safeguards for improved flood control and utilize funding authorized by the Safety of Dams Act.

  • 1989

    A weed control pilot program is launched and includes a unique solution - the introduction of over 1,700 white amur into portions of the Tempe and Crosscut canals. The white amur fish eats more than it’s weight in water vegetation every day and proves an effective weed control, reducing the use of chemical treatments.
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    Controlling aquatic weed growth in SRP’s canal system has been a challenge since the early days. Left unchecked, weeds impede water flow and displace space in the canal needed for water transport. Past weed control methods included scraping canal beds with heavy chains to uproot plants, scooping out vegetation with backhoes or applying herbicides.

  • 1994

    Kent DecreeSRP begins banking water at the Granite Reef Underground Storage Project (GRUSP) to help ensure a reliable and adequate supply of water for the growing Phoenix metropolitan area.
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    GRUSP was designed to enable the state of Arizona to maximize use of its Colorado River entitlement and help the state reach its "safe yield" goal. Safe yield is the equilibrium between the amount of groundwater pumped from an aquifer and the amount recharged into it.

  • 1996

    A modification project is completed raising the height of Theodore Roosevelt Dam and expanding the lake's storage capacity. This increase offers Valley cities more water and, for the first time, provides SRP with substantial amounts of flood control and storage space.

  • 1999

    The M-Power program, designed to help customers better track their energy use and lower costs, begins and quickly grows to become the largest prepay program among U.S. utilities by 2011.

  • 2000

    SRP receives the coveted Award for Excellence in Workplace Volunteer Programs for 2000 from the Points of Light Foundation based in Washington, D.C., one of the world's highest and most distinguished awards for community and volunteer service.

  • 2003

    A new smart meter program is launched improving service with faster response times, greater customer access to energy use data, wider participation in time-of-use plans, and a variety of new service options.

  • 2005

    SRP acquires C.C. Cragin (formerly Blue Ridge) reservoir from Phelps Dodge Corporation as part of the Gila River Indian Water Rights Settlement approved by the Arizona Water Settlement Act.
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    The agreement settles water rights issues and allows for the transfer of C.C. Cragin reservoir from Phelps Dodge to SRP. The additional water supply is used to meet domestic and municipal water demands in northern Gila County.

  • 2006

    SRP's Board of Directors approve a management proposal that directs SRP's future use of renewable energy resources and energy conservation measures.
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    Among them are a diversified resource mix of wind, geothermal, large hydro (added in 2007) and low-impact hydro and landfill gas. The approved portfolio sets a target of 15% of SRP retail sales to be met through sustainable resources by fiscal year 2025.

  • 2007

    The New River-Agua Fria River Underground Storage Project (NAUSP) is completed. It is the second groundwater recharge facility that SRP has developed working in partnership with cities and the first in the West Valley.
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    NAUSP is operated by SRP and owned by SRP, Avondale, Chandler, Glendale and Peoria. It has a storage capacity of 75,000 acre-feet per year and, along with GRUSP, allows SRP to store water underground for use during dry years.

  • 2008

    On July 31, it is announced that SRP will buy 63 MW of power form the Dry Lake Wind Power Project, Arizona's first wind energy farm.

  • 2011

    The past and future come together as Theodore Roosevelt Dam turns 100 and the new Copper Crossing Solar Ranch in Florence is dedicated expanding SRP's renewable energy portfolio. The solar plant produces enough renewable energy to power 3,700 homes.

  • 2012

    Two more renewable energy sources, geothermal and solar, come online and SRP strikes a deal with the Gila River Indian Community (GRIC) that will allow GRIC to store, and therefore use, more of its Central Arizona Project (CAP) water allocation.
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    The agreement with GRIC provides a portion of its CAP allocation to municipal water providers as an assured water supply and SRP with access to supplemental water for its shareholders if needed.

  • 2015

    Flowtography® is developed by SRP researchers and used in the Salt and Verde watersheds to collect river and stream flow data to help manage the watersheds.
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    SRP partners with numerous entities to expand where the monitors and gauges that collect the data are installed.

  • 2016

    The Sandstone Solar plant opens in Florence, Arizona, adding 45 MW to SRP’s renewable energy portfolio. Research begins at Coronado Generating Station to determine if forest debris, resulting from forest thinning, can be used as another energy source when mixed with coal.

  • 2017

    In October, the 2035 Sustainability Goals are approved by SRP's Board of Directors. The goals provide a framework for moving forward sustainably while continuing to provide affordable water and power.

    Another milestone occurs in November when SRP celebrates it's 100 year partnership with the U.S. Bureau of Reclamation (BOR).
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    On Nov. 1, 1917 the BOR transferred operational control of a federal reclamation project – the Salt River Reclamation Project – to a local entity – the Salt River Valley Water Users’ Association. Watch a video .

  • 2018

    At the beginning of the year SRP signs a landmark agreement with Navajo Tribal Utility Authority to expand the Kayenta Solar generation facility providing more renewable energy to the Navajo Nation. The additional facility, called Kayenta II, takes advantage of the existing interconnect, trained workforce and generates an additional 27.3 MW.

    On March 5 SRP's Board of Directors selects Mike Hummel to succeed Mark B. Bonsall as the General Manager and Chief Executive Officer.