By Keriann Conroy on August 20, 2025
Coolidge Generating Station, a gas plant in Arizona, consumed 107.43 acre feet of groundwater last year, according to documents provided by Salt River Project (SRP), the utility that owns the plant and is planning to expand it.
Declining groundwater is a massive concern in Arizona. Despite the fact that the Coolidge plant’s groundwater consumption has been modest – equal to the amount of water that 650 Arizonans use in a year – the Arizona Corporation Commission (ACC) required SRP to discontinue groundwater consumption from the plant as a condition of approving its controversial expansion.
Coolidge is one of the largest gas “peaker” plants in Arizona, coming on only during the hottest summer hours, when electricity demand is highest. Despite being a high polluting facility when it operates, Coolidge represents a small fraction of total power generation and water consumption in the state. The scale of water consumption by Arizona’s power plants is largely unknown, as utilities are not required to publicly report water consumption data.
Power plant water use data is not readily available in Arizona
EPI obtained records on Coolidge’s water consumption through a public records request to SRP, because SRP is a public subdivision of the state, regulated by its governing board, rather than the ACC. The ACC does not require the power plant-owning utilities it regulates, such as Arizona Public Service (APS), Tucson Electric Power (TEP), and UniSource Electric Services (UNS), to provide data on the total annual water consumption volume for utility-owned power plants. EPI is waiting on requested records from the Arizona Department of Water Resources for data on the water consumption at other utility-owned gas-fired power plants.
In its response to EPI, SRP asserted, “while it is SRP’s position that it is not subject to the Public Records Act, SRP has nevertheless searched its records and voluntarily produces the enclosed records and data below which are responsive to your Request.” Despite SRP’s position, earlier this year the Arizona Court of Appeals ruled the utility is subject to public records laws in the state.
Water matters to Arizona Voters
Water use is a top issue for Arizona voters. Leading up to the 2024 general election, the Center for the Future of Arizona released a survey conducted by HighGround Public Affairs showing that 93% of Arizona voters supported the “need to do more to protect groundwater and secure long-term water supplies.” The survey found that only 33% of voters believed Arizona’s current water policies are sufficient to ensure long-term water sustainability. Paul Bentz, senior vice president of research and strategy at HighGround Public Affairs, said of Arizona voters that “there is a strong appetite for candidates who understand water issues and want to take action on them.” Still, the topic of water policy is “complicated, that’s why candidates stay away from it.”
Fossil fuel-producing power plants in Arizona pose significant water risks. Climate analysis indicates that future increases in water withdrawals can be offset by transitioning energy sources from fossil fuels to solar photovoltaics and wind in the power sector, as these technologies require minimal water to operate.
Climate implications and data center growth impact Arizona water issues
Water scarcity and demand for more water due to economic growth fuel the concern over water issues in Arizona. Since the start of the 20th century, temperatures in Arizona have risen by 2.5°F due to human-caused climate change, which is linked to persistent drought in the southwest region of the United States. Higher temperatures cause the atmosphere to pull more water from the soil, meaning that even if rainfall remains the same, less water will find its way to rivers – where Arizona gets 54% of its water – because more is going back into the atmosphere. This evaporative process has increased over the last 40 years, with the most intensity in the U.S. Southwest. In addition, groundwater supply – where the state obtains 41% of its water – continues to shrink, a new study shows. Research highlights that the loss is due to drought conditions, agricultural use, and increased urban growth demands. The Coolidge plant historically and currently uses groundwater, which is difficult to recover as temperatures rise.
Water is also a key input into thermal power generation, like at coal, gas and nuclear power plants. Utilities, such as Arizona Public Service (APS) and SRP, are currently breaking energy demand records as temperatures climb in the state. Arizona expects substantially larger increases in energy demand in the coming years due to population growth, rising temperatures, and an increase in data centers. The increased demand on the grid from data centers could increase utility bills for customers, prompting the ACC to open a docket on the matter to investigate the financial impact to ratepayers.
Data centers require large amounts of power, generating a significant amount of heat that requires cooling systems often run on electricity, with some building new electric infrastructure powered by methane gas or renewables. APS, SRP, Tucson Electric Power (TEP) and UniSource Electric Services (UNS) recently backed a new, 600 mile methane gas pipeline expansion project built by Transwestern Pipeline Company. In an earnings call the same day, APS CEO Ted Geisler emphasized the importance of meeting data center demand with the long-term methane gas procured from Transwestern.
Some companies use large amounts of water to cool their data centers. In Tucson, a data center in development, Project Blue, is expected to use 870 acre feet of water per year, nearly 8 times the amount Coolidge Generating Station currently uses.
ACC reverses decision on Coolidge expansion
In 2021, SRP sought approval to expand the Coolidge Generating Station. Environmentalists and community members came out in opposition, concerned over SRP’s climate commitments and the health and environmental impacts on the surrounding, historically Black community of Randolph. After concluding SRP had failed to consider viable cleaner alternatives, the ACC rejected the proposal and denied SRP’s request for a new hearing and the Maricopa County Superior Court upheld the ACC’s decision to deny SRP’s proposal.
However, in 2023 – when two new Republican commissioners, Kevin Thompson and Nick Myers, joined the ACC – the Commission reversed its decision, with Commissioner Lea Marquez Peterson changing her vote to approve the expansion, allowing a doubling of the plant size from 575 MW to 1150 MW. As a gas “peaker” plant in Arizona, Coolidge is less efficient than a standard gas plant and emits more pollutants, subjecting surrounding communities to many adverse health effects.
