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General Description| Plan| Development| Benefits

General Description

The Salt River Project, located near Phoenix, Arizona, includes a water service area of about 375 square miles and an electric service area covering 2,900 square miles spanning portions of Maricopa, Gila and Pinal Counties in central Arizona. Water supplies from the Salt and Verde Rivers are controlled by six storage dams, two of which were constructed by the Bureau of Reclamation. A diversion dam constructed by Reclamation serves 1,300 miles of canals, laterals, and ditches that wind across 240,000 acres of land.

The power system includes five hydroelectric plants; three steam plants, two with separate combustion-turbine installations; and a combined-cycle plant. The project's managing entity, also known as Salt River Project (SRP), owns interests in five coal-fired generating stations, four natural gas-fired plants, and the Palo Verde Nuclear Generating Station.

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Water is furnished by the Salt and Verde Rivers, which drain a watershed area of 13,000 square miles. The four storage reservoirs on the Salt River form a continuous chain of lakes almost 60 miles long. An important supplemental supply is obtained from well pumping units.

Irrigation flow is regulated by Bartlett Dam on the Verde River and Stewart Mountain Dam on the Salt River. Downstream of the confluence of the Verde and Salt Rivers, water is diverted to two main canals at the Granite Reef Diversion Dam. The Arizona Canal serves the north side of the project; the South Canal serves the south side. From the two main canals, water is diverted to secondary canals, then to laterals through which the water is delivered to farms and cities. Total storage capacity of Salt River reservoirs is more than 2.3 million acre-feet. The combined storage capacity of the two reservoirs on the Verde River is 287,403 acre-feet.

Total hydroelectric generating capacity is 238 megawatts, including power from the pumped storage units at Horse Mesa and Mormon Flat Dams. Turbine generating units at these two dams produce power during periods of peak demands. The turbines can be reversed to pump water during off peak periods from the lower reservoir back to the upper reservoir for repeated usage. As part of the same program, which began in 1969, existing units at the two dams were converted from 25 to 60 hertz, and one new 60-hertz unit replaced the former 25-hertz units at Theodore Roosevelt Dam. A hydroelectric unit located on the Crosscut Canal, which links the project`s two major canals, provides additional hydroelectric capacity.

Facility Descriptions

Theodore Roosevelt Dam, the first major structure constructed by the Bureau of Reclamation on the Salt River Project, is located about 76 miles northeast of Phoenix and 30 miles northwest of Globe, Arizona. The dam, completed in 1911, was subsequently modified between 1989 and 1996. The original dam -- once the world's tallest masonry dam -- was a cyclopean, rubble-masonry, thick-arch structure that spanned the Salt River to form a reservoir of 1,381,580 acre-feet. It was 280 feet high, 723 feet long at the crest, and contained 355,800 cubic yards of masonry,

In 1936, the spillways were modified by lowering crests 6 feet to increase their capacities, and installing individual gate hoists, operating motors, and two 5-kilovolt-ampere gasoline-engine driven generators.

From 1989 to 1996, the dam was modified by the Bureau of Reclamation. The modification raised the dam 77 feet in elevation, increasing its water conservation storage capacity by 20 percent, adding flood control space to the reservoir, and addressing concerns about its safety as well as the safety downstream dams. In addition to raising the dam's height, the modification included construction of two new spillways, installation of new outlet works, and powerplant modifications. Also, existing recreation facilities at Roosevelt Lake were improved, and new recreational facilities were constructed.

Roosevelt Lake  is 22.4 miles long, with 128 miles of shoreline and almost 21,500 surface acres.

Located on the Salt River 65 miles northeast of Phoenix, Horse Mesa Dam is a concrete thin-arch structure 305 feet high and 66 feet long. Constructed by the Salt River Valley Water Users' Association between 1924 and 1927, the dam contains 162,000 cubic yards of concrete, and forms a 245,138 acre-foot reservoir called Apache Lake.

The spillway, as modified in 1936 by the Bureau of Reclamation, includes a 50,000 cubic-foot per second, concrete-lined auxiliary tunnel, 30 feet in diameter and 400 feet long; a regulating gate, gatehouse, and operating mechanism for controlling the tunnel; and a concrete discharge apron below the existing spillway. The piers on the radial-gate spillways were thickened, individual motor-driven gate hoists were installed, and two 15-kilovolt-ampere gasoline-engine driven generators were installed for emergency operation of the hoist motors.

The dam has three hydroelectric generating units rated at a total of 32,000 kW, and a pumped storage unit rated at 97,000 kW added in 1972.

Apache Lake is 17 miles long, with 41 miles of shoreline and more than 2,600 surface acres.

Mormon Flat Dam, a 224-foot high concrete thin-arch structure, is on the Salt River 51 miles northeast of Phoenix. Constructed by the Salt River Valley Water Users' Association from 1923-1925, it creates a 57,852 acre-foot reservoir called Canyon Lake.

In 1938, Reclamation completed construction of a new gate structure and a concrete-lined spillway discharge channel, and installed two 50-foot-square stoney regulating gates, hoists, motors, two 25-kilovolt-ampere gasoline-engine driven generators, and a new road to the powerhouse.

The dam has two hydroelectric generating units - a conventional unit rated at 10,000 kW and a pumped storage unit built in 1971 and rated at 50,000 kW.

Canyon Lake is 10 miles long, with 28 miles of shoreline and 950 surface acres of water.

On the Salt River 41 miles northeast of Phoenix, Stewart Mountain Dam created Saguaro Lake, a 69,765 acre-foot capacity reservoir. The dam is a concrete thin-arch structure, 212 feet high and 583 feet long. When built by the Salt River Valley Water Users' Association from 1928-1930, the dam included an open, super-elevated channel spillway equipped with radial gates.

The spillway was modified by Reclamation in 1936. The work consisted of building a concrete-lined spillway discharge channel, 450 feet long by 265 feet wide, below the existing ogee spillway; reconditioning the hoisting equipment for the radial gates; and installing individual gate operating motors and two 10-kilovolt-ampere gasoline-engine driven generators.

From 1988 to 1992, the dam was again modified by Reclamation, to meet concerns about its stability in a probable maximum flood (PMF) or maximum credible earthquake. To address PMF concerns, a new spillway was constructed on the dam`s right abutment to increase its ability to safely release flood waters. As part of earthquake protection measures, a new concrete overlay was placed over areas on the right and left abutments to improve the dam`s stability. The existing power penstock and river outlet works were also replaced, the road on the top of the dam was raised and widened, and the existing left spillway and spillway wall was modified. In addition, drainage holes were drilled at selected locations in the dam`s foundation to help relieve hydraulic uplift pressures, and some areas of the foundation were grouted to help reduce seepage. Finally, 84 steel cables were installed through the dam and into its foundation to strengthen it.

The dam has a hydroelectric generating unit rated at 13,000 kW, which is operated primarily in the summer months.

Saguaro Lake is 10 miles long, with 22 miles of shoreline and a surface acreage of 1,264 acres.

From 1936-1939, Bartlett Dam was constructed by Reclamation on the Verde River, 48 miles northeast of Phoenix. Before its modification, this multiple-arch dam was 287 feet high and contained 182,000 cubic yards of concrete; it creates a 178,186 acre-foot capacity reservoir known as Bartlett Reservoir.

Bartlett Dam was modified in the mid-1990s by Reclamation to address safety concerns. The modification, initiated in March 1994, included construction of a new, unlined auxiliary spillway about 1,500 feet south of the dam's left abutment, along with a concrete control structure and three-segment fuseplug embankment along with training dikes. In addition, the dam was raised 21.5 feet to prevent overtopping, and the walls and bridge of the existing service spillway structure were modified. Modifications were completed in December 1996.  The dam now stands 308.5 feet high and is 800 feet long.

There are no hydrogenerating units at this dam.

Bartlett Lake is 12 miles long, with 33 miles of shoreline and a water surface acreage of 2,815 acres.

Horseshoe Dam, on the Verde River 58 miles northeast of Phoenix, is an earthfill structure 194 feet high, with a reservoir capacity of 109,217 acre-feet. Horseshoe Dam was built from 1944-1946 by the Phelps-Dodge Copper Products Corp. for the Salt River Valley Water Users' Association under a water exchange agreement. Spillway gates were added to the dam in 1949 by the city of Phoenix to increase the domestic water supply.

Horseshoe Dam was modified in the mid-1990s by Reclamation to address concerns about its safety in the event of a Probable Maximum Flood or Maximum Credible Earthquake. Modifications included construction of a fuse plug auxiliary spillway with an erodible embankment and a concrete foundation 2,000 feet west of the existing spillway. In addition, a 148,000 cubic-yard stability berm was constructed at the downstream toe of the dam to help stabilize it in the event of an earthquake, and the dam was raised eight feet to enable the spillway to pass the Probable Maximum Flood. To prevent overtopping of the structure from wave action, an additional 4-foot parapet was built on the dam's crest. Other work included relocation of the dam tender facilities, upgrading the road to the public boat ramp, and study and protection of archaeological artifacts during construction.

The dam has no hydroelectric generating capabilities.

Horseshoe Lake is 5 miles long, with 27 miles of shoreline and covers more than 2,700 acres.

Granite Reef Diversion Dam is located about 4 miles downstream of the confluence of the Salt and Verde Rivers and about 22 miles east of Phoenix. The 29-foot-high, 1,000-foot-long concrete ogee weir dam was constructed between 1906 and 1908 by Reclamation to divert water released from the two rivers to project canals.  There are no recreational or hydroelectric facilities at the dam.

SRP acquired C.C. Cragin (formerly Blue Ridge) Dam and reservoir from Phelps Dodge Corporation in February 2005 as part of the Gila River Indian Water Rights Settlement approved by the Arizona Water Settlements Act.  Located on East Clear Creek near Payson, Arizona, the project consists of several facilities including a dam, reservoir, pumping plant, pipeline, electrical transmission line, and generating plant.  The project is being used to satisfy water delivery obligations to the Gila River Indian Community, as well as supplement Salt River Project water supplies and improve water supplies for northern Gila County. 

Blue Ridge Dam and reservoir became a part of the federal Salt River Project on September 30, 2005 when title to the facility was transfered from SRP to the United States.  The facilities were renamed in honor of Charles Calhoun Cragin, general superintendent of the Salt River Valley Water Users' Association from 1920-1933.

Well Pumping Units

Pumps are installed on 250 wells to supplement the surface water supply. The total pumping capacity of these wells is 738,595 acre-feet. Several booster pumps have been installed to lift water to canals and laterals through low lifts ranging from 3 to 40 feet. 

Distribution and Drainage System

A total of 131 miles of irrigation canals, 878 miles of laterals, and 250 miles of drain ditches make up the water distribution system.  The banks of the canals are popular recreation areas, open for walking, running, bicycling and special events in most areas.

Operating Agencies

The SRP -- which operates these facilities -- is two entities: the Salt River Project Agricultural Improvement and Power District, a political subdivision of the state of Arizona; and the Salt River Valley Water Users' Association, a private corporation.

The Salt River Valley Water Users' Association operated and maintained the irrigation and drainage system below Granite Reef Diversion Dam from 1917 to 1949, and the power features were operated by the Salt River Project Agricultural Improvement and Power District until 1937. In 1937, the Association transferred all of its rights, title and interest in the Salt River Project to the District. In 1949, the original agreement was amended so the District would assume construction, operation and maintenance responsibilities for both the electric and irrigation systems. The District then delegated to the Association operation and maintenance of the irrigation and water supply system of the project.

SRP is now the third-largest public power utility in the nation serving more than 890,000 electric customers in the greater Phoenix metropolitan area.

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Irrigation of the Salt River Valley began about 1867. The river flow was erratic, varying from a small stream to enormous floods. During years of drought, the supply of water at low river stages was inadequate for the land in cultivation. River flows in excess of immediate needs or canal capacities were lost, due to lack of storage facilities.

From 1867 to 1902, a number of diversion dams, canals, and laterals were constructed by private companies or through community effort. Difficulties caused by lack of water storage, inadequate diversion dams, and inequitable water distribution were so critical that many settlers left the valley. A committee was named to investigate the feasibility of a water storage system. A reservoir site located 80 miles from Phoenix, where Tonto Creek flowed into the Salt River, seemed the most practical.

Such a reservoir would cost from $2 to $5 million. As a territory of the United States, Arizona was prohibited from assuming such a large-scale debt; private investors could not be induced to take on the financial risk necessary to construct the dam.

The Salt River Valley Water Users' Association was incorporated on February 7, 1903, for the purpose of furnishing water, power, and drainage for the benefit of approximately 4,800 individual landowners.

Power Developments

When Phoenix and the surrounding communities began to grow, patterns of water distribution were affected. A great impact was also felt on electrical services provided by SRP.  To address these growing energy needs, SRP operates or participates in a number of major thermal and hydroelectric powerplants and generating facilities in Arizona and throughout the Southwest.

In 1947, power sources included the hydroelectric facilities at the dams, a 3 MW hydro-plant on the Crosscut Canal, and gas/oil-fired units at Crosscut. In 1952, the Kyrene Generating Station, south of Tempe, was placed in operation.  The 521 MW capacity plant has six units: two original steam units, three combustion turbines, and one combined-cycle unit.

In 1957, the Agua Fria Generating Station, located west of Glendale, was placed in operation. Since then, the station's capacity has been increased to 626 MW.  It contains three steam generation units and three combustion turbine generators, along with a 200 kW solar generating unit.

In 1969, SRP initiated its Hydroelectric Expansion and Frequency Unification (HEFU) program to increase hydroelectric generating capacity at facilities on the Salt River. This program included the installation of pumped storage units at Mormon Flat Dam in 1971 and at Horse Mesa Dam in 1972. The HEFU program also provided for converting the conventional hydroelectric generating facilities at the dams on the Salt River from the outmoded 25-hertz (Hz) to the modern frequency of 60 Hz and in 1973, a new 60-Hz, 36-MW generating unit was installed at Theodore Roosevelt Dam, which replaced the existing 25-Hz units.

In 1974-1975, the four-unit combined-cycle Santan Generating Station was built near Gilbert, Arizona. Originally comprised of four combustion and steam generation units, each with a capacity of 92 MW,  the station has been uprated over the years with several gas and steam units, bringing the facility's capacity to 1,225 MW.

In December 1979, the project completed Unit 1 at its coal-fired Coronado Generating Station near St. Johns, Arizona. In October 1980, the plant's second unit was completed, bringing it to its full 773-MW capacity.

The SRP purchased the Desert Basin Generating Station in Casa Grande, Arizona, in October 2003.  A combined cycle natural gas-fired generating plant, it contains five units with a combined capacity of up to 577 MW.

SRP Participation in Power Projects

The SRP and five Southwestern utilities invested in the construction of two of the large coal-fired units at the Four Corners Generating Station near Farmington, New Mexico. The project has a 10-percent share of units 4 and 5 of the 2,040-MW capacity plant. First power was received in 1969 and the last unit went on line in 1970.

In 1974-1976, three coal-fired units came on line at Navajo Generating Station near Page, Arizona. The SRP manages the station and receives 21.7-percent of its installed capacity, which is 2,250 MW.

In 1976, a second unit of the Hayden Generating Station at Hayden, Colorado, was completed. The SRP receives 50 percent of the 262-MW coal-fired unit`s capacity.

The 1,580-MW Mohave Generating Station near Laughlin, Nevada, was built by a regional group of utilities between 1967 and 1971. The project has a 10 percent interest in this station. Power from the first unit was delivered in 1970 and the second unit became operational in 1971.  The plant ceased operations on Dec. 31, 2005, consistent with the provisions of an agreement reached with several environmental groups. 

Between 1974 and 1984, the Craig Generating Station was constructed near Craig, Colorado.  Consisting of three coal-fired generating units, the 1,283-MW plant provides about 248 MW (29 percent of Units 1 and 2) for SRP purposes.

The Palo Verde Nuclear Generating Station was constructed 55 miles west of Phoenix, Arizona, from June 1976 to January 1988. SRP is one of the seven utilities that receives power from the 3,739 MW-capacity plant. SRP's share is 17.5 percent, or about 654 MW.

The coal-fired Springerville Generating Station in Springerville, Arizona, near the border with New Mexico, was constructed between 1985 and 2006.  SRP is presently constructing Unit 4 at the 1,160 MW plant, bringing the facility's expected capacity to 1,560 MW.  SRP owns the new 400 MW unit, expected to be in operation by December 2009.


The project was investigated and found feasible by the Director of the Reclamation Service on March 7, 1903.


The project was authorized by the Secretary of the Interior on March 14, 1903, in accordance with the act of June 17, 1902 (32 Stat. 338). Rehabilitation and betterment of the project works was authorized by the act of October 7, 1949 (63 Stat. 724), as amended.


Construction began on August 24, 1903, and the first water was delivered in 1907.

The original project system, composed of Theodore Roosevelt Dam and Powerplant, Granite Reef Diversion Dam, and the improved main canals, was placed in service in 1909 and completed in 1911. The Salt River Valley Water Users' Association built Horse Mesa, Stewart Mountain, and Mormon Flat Dams between 1923-1930. On November 26, 1935, the Association entered into a contract with the Bureau of Reclamation for the construction of Bartlett Dam; reconstruction or repairs to the spillways at Horse Mesa, Mormon Flat, Stewart Mountain, and Theodore Roosevelt Dams; and other improvements. All work was started in 1936 and completed by 1939. In 1946, the Phelps-Dodge Corporation completed Horseshoe Dam on the Verde River under a water exchange agreement. From 1989 to 1998, Reclamation modified several dams on the Salt and Verde Rivers to meet updated safety and operational criteria for these structures.

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Irrigation water from the project helped transform a part of the Arizona desert into fertile farmland that produces millions of dollars worth of crops annually. Today, the project delivers nearly a million acre-feet of water to municipal, agricultural and urban irrigators in a 240,000-acre service area each year.


The SRP, with an installed capacity of more than 8,000 MW, provides electric service to more than 890,000 residential, business and industrial customers in a 2,900-square-mile service area in parts of Maricopa, Gila, and Pinal Counties.

Flood Control

Capacity assigned to flood control is more than 1.6 million acre-feet. To date, Salt River Project dams have provided accumulated flood control benefits of nearly $2 billion.


All reservoirs located on the Salt and Verde Rivers offer year-round boating and fishing for a variety of warmwater fish species. Waterfowl hunting is permitted in season. Theodore Roosevelt Lake contains a wildlife area and, as a wildlife refuge, is posted to permit hunting at certain times of the year. Theodore Roosevelt and Apache Lakes offer year-round motel facilities. Canyon, Saguaro, and Bartlett Lakes offer a variety of camping, picnicking, swimming, and other outdoor recreation opportunities. The Salt River below Stewart Mountain Dam and the cool waters of Cragin Reservoir offers outstanding trout fishing during certain times of the year.

The U.S. Forest Service operates several recreation sites and marinas around some of the reservoirs created by SRP dams; the Arizona Game and Fish Department and county sheriffs' offices help manage and protect the natural resources near these facilities.

The canals of the Salt River Project also offer extensive opportunities for walkers, hikers, joggers and bicyclists.  Portions of the 300-mile Sun Circle Trail run adjacent to the Arizona Canal joining several communities in the Phoenix valley. 

For specific information about Salt River Project recreation sites, click on the name below.

Apache Lake
Blue Ridge (CC Cragin) Reservoir
Bartlett Lake
Canyon Lake
Horseshoe Lake
Saguaro Lake
Theodore Roosevelt Lake
Boating on SRP Lakes


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Last updated: Aug 19, 2011