An immediate start on work to prepare for direct potable water reuse and seawater desalination is proposed by the Arizona Department of Water Resources (ADWR) in a report recently published by the US state’s government.
The report, Going Forward: A Strategic Vision For Water Supply Sustainability, says that Arizona could be facing a water supply imbalance between projected demands and water supply availability in the next 25‑50 years of approximately 900,000 acre‑feet (AF; 1,110 million m³). This would increase to 2.3 million AF (2,840 million m³) by 2110, says the ADWR.
Emphasising that no single strategy will work right across the arid state, it nonetheless points out that Arizona is a leader in the reuse of reclaimed water, but has only taken advantage of “a fraction” of its reuse opportunities. Underground storage of unused reclaimed water during times of excess supplies and recovery of those supplies during higher demand seasons is a way to meet demands, says the report.
“Using this supply that is readily available also reduces or delays the need to find alternative, more expensive, water supplies,” the report states. “Addressing legal hurdles and ensuring the public that this is a safe source of water needs to start now to ensure that direct potable reuse of reclaimed water will be available when it is needed.”
The ADWR acknowledges that water will have to be imported into the state to allow continued economic development without water supply limitations. It sees desalination as a technology meeting this need.
The first desalination source for the land-locked state could be potential partnerships with other higher priority Colorado River users in Arizona, California and Nevada in exchange for water from Lake Mead. But, as Arizona’s border is only 50-60 miles (80-95 km) from the Mexican coastline, another route is being looked at.
“Additionally, advancing Governor Brewer’s initiative to work cooperatively with Mexico through the Arizona Mexico Commission, developing much need water supplies for both Arizona and Mexico through desalination on the Sea of Cortez could prove most effective,” the report suggests.
Pointing out the cost and investment required, the ADWR concludes: “Because of the time it takes to develop these projects, and the more pressing need for water supplies in certain parts of the State, exploration of this strategy should begin immediately.”