YEAR BUILT: 1914 

HISTORY 
Despite the semi-arid, desert-like climate in central Arizona, farming has been made possible by damming the Salt and Verde Rivers. Damming the rivers was done by the US Bureau of Reclamation in the early 1900s. These dams also allowed for the Salt River Project (SRP) to generate electricity via hydro plants located at dam sites.

The first hydro plants in Arizona were positioned along natural falls in the canal system. These plants were initially operated by Arizona Light and Fuel Company.

Early plans for the Roosevelt Dam also included a hydro plant that was used to fuel its initial construction. Originally, the hydro plant was to be converted to a pumping plant or sold off. However, upon completion, the dam raised the water table and the pumps ended up being used to drain water from thousands of acres of nearly waterlogged land.

Roosevelt Dam continued to produce power via its hydro plant when it started commercial operation in 1909. However, even before then, it had become apparent that the dam could not keep up with electrical demand, so the Bureau of Reclamation started looking for new sites that were feasible for hydro plants along SRP’s waterways.

In 1907, the government struck a deal to acquire the Arizona Falls and Indian Crosscut plants from Pacific Gas & Electric. After purchasing the plants, the federal government allotted a certain amount of electricity to the company to continue selling while the government agreed to only sell to large industrial customers.

To deliver electricity to and across the Valley of the Sun, the government constructed an electrical distribution system. The main line ran from Roosevelt Dam to the Mesa Switchyard and Phoenix Substation. Additional branches off the main line were added over the following years to provide power to different companies such as the Inspiration Consolidated Copper Company in Miami, Arizona.

However, by 1910, the cost of the Salt River Project had far exceeded its previously estimated $3 million and no more funds were available from the Reclamation Act. Instead, to offset costs, a legal advisor for the Water Users’ Association proposed that they build hydropower plants along the canals and sell the electricity to reduce repayment costs.

This proposal included extending the existing Grand Canal until it met the newly proposed Crosscut Canal. The proposal was approved by the US Department of the Interior, and a contract was drawn up that outlined the conditions for the new hydro plant. The construction would be overseen by the Reclamation Project and, upon completion, turned over to the federal government to become part of the Salt River Project. Additionally, the Salt River Project would not officially open until the hydro plant was completed.

The first phase of construction was building the 3.5-mile Crosscut Canal that extended from the existing Arizona Canal to the Grand Canal. The intersection of the Crosscut and Grand Canals created a 112-foot drop that could be taken advantage of by the hydro plant. While the primary focus was to prioritize electrical generation, the new location was also billed as being designed to provide maximum efficiency for water distribution.

Construction on the Crosscut Power Plant started in September 1913 and ended in November 1914. The building was mostly completed by the spring of 1914 and machinery had started to be installed. However, additional work was done on the plant through 1915 to ensure efficiency and reliability standards were met. Numerous issues were found during testing, including hairline cracks in the pipes caused by shrinkage and the “chattering” of the valves when being turned. As a result of the repairs and replacements that had to be done, the required 30-day test was not conducted until December 15, 1915.

Despite not starting the testing until the last month 1915, the Crosscut Power Plant generated the second largest amount of electricity for SRP that year. When the hydro plant was put into full service, it represented 40% of SRP’s generating capacity. The hydro plant operated for 24 years and served as a reliable power source despite its increasingly evident shortcomings, such as issues with the transformers and distribution equipment. Repairs happened frequently but few changes were made to permanently fix many of the problems.

As the demand for electricity increased and drought continued, SRP contracted with the Central Arizona Light and Power Company (CALAPCO) and the Inspiration Consolidated Copper Company to build a steam-generating plant. This steam generating plant provided additional electricity; however, the contract was for a limited time and SRP had to find more long-term solutions for power generation. The solutions they found were to build their own non-hydro generation plant and to modernize the Crosscut Power Plant.

Over a 12-year period, generation units were added and removed from the Crosscut Power Plant. These units were all connected and consisted of a combination of hydro, diesel, and steam generation units. The addition of these units and additional upgrades to the plant allowed it to go from performing 25 cycles to 60 cycles, enough to power the City of Mesa.

In the mid-1950s the plant’s last three 25-cycle generation units were decommissioned and removed. The plant continued to use a 60-cycle generation unit to help with summer-time electricity demands. However, despite the occasional use, the building was converted for use as storage and a hydrology laboratory. In 1979, the plant was renovated again to run continuously from May to September at a low cost. It supplemented SRP’s more expensive power sources through 1990.

Currently, the Crosscut Power Plant only runs on a “water order”-only basis. This means that water only runs through the plant when someone orders their water shares and only when those water shares reach an amount that is large enough to operate the plant.

ARCHITECTURE
The Crosscut Power Plant is rectangular in shape and measures 176 feet by 42 feet, with a maximum height of 63 feet. It is a cast-in-place concrete structure with a gable roof and ridge vents. The building is divided into 12 bays on the long sides and 3 bays on the short sides. Each bay has one metal window that is 4-over-4 light double-hung. Concrete work includes simplified classical motifs; these are located beneath the frieze panels and consist of a corbelled band course and pilaster capitals.

The building’s main entrance is on the north side, with additional garage access on the south. The floor with the main generator is located 22 feet above the tailrace (water exit). The roof is supported by metal trusses.

To the east there are two more buildings: the switching and transformer building and a shop. Both buildings are concrete with similar detailing and openings. However, unlike the main building, these two auxiliary buildings have flat concrete roofs. In 1938, a diesel-powered metal steam generating plant was constructed in the northwest of the site. This building was constructed in the Moderne style and sheathed in corrugated metal with multiplane, steel-frame awning windows.

BIBLIOGRAPHY
Crosscut Steam Plant - HAER No. AZ-30. Historic American Engineering Record. June 7, 1991.

Janus Associates. “Inventory Number 183.” In Tempe Historic Property Survey. 1983.

National Park Services.  “Arizona: Crosscut Powerplant.” Archived on February 24, 2025, at https://web.archive.org/web/20250202090444/https://www.nps.gov/articles/arizona-crosscut-powerplant.htm.

“Our Power Generation Sources.” Salt River Project. Archived on March 25, at https://web.archive.org/web/20250212182558/https://www.srpnet.com/grid-water-management/grid-management/power-generation-stations.