The Valley’s two largest water providers will connect their systems, allowing water from the Salt River Project into the Central Arizona Project canal system.
The project would give SRP and CAP the flexibility to move water through the Valley. Combined, the two providers serve the vast majority of Arizonans.
SRP water comes from the Salt and Verde Rivers. CAP water comes from the Colorado River and is in danger of taking cuts. SRP and CAP have different service areas.
The proposed SRP-CAP Interconnection Facility (SCIF) would allow water users, like some central Arizona cities and towns with rights to SRP water to access it.
“It's water that belongs to these municipalities that have invested in infrastructure within SRP service territory that they may not have access to currently,” SRP Senior Engineer Jacob Rodriguez said.
Rodriguez said it provides users with more security in times of strain.
“If there's shortages, depending on just, you know, climate change and, we have times of very wet years and very dry years, it provides them with that flexibility,” Rodriguez said. “It's a project for those that have non-SRP shareholder water stored within our service territory for them to be able to have access to that water.”
The SCIF proposal has been discussed for several years. Although SRP made its official proposal in 2020, the project is still in early stages.
In the rare occurrence when SRP’s reservoirs go over capacity, as during a major storm, the provider has had to release excess water. SCIF would potentially be a way to use more of that excess water by adding it to the CAP system, but Rodriguez said it won’t necessarily eliminate spills.
“If this project had been in place in 2023, there would have been more than enough capacity to move 50,000-acre feet of water from SRP during the high-water periods that spring to water treatment plants or underground storage facilities along the CAP system, instead of it being spilled downstream,” Arizona Congressman Greg Stanton said in a statement on Jan. 15.
SCIF will not expand SRP’s service territory or serve as a way to transition CAP users to SRP water. But it allows municipalities to cash in their water credits.
How it works
Several Valley cities, including Tempe, Avondale, Phoenix and Scottsdale hold long term water storage credits, which are water rights.
When the cities want to draw on those supplies, the water is drawn from SRP wells. But the water can only currently be delivered through the SRP system.
The problem with that is, much of those water credits are meant for growth outside of SRP’s service area in places like Apache Junction and Buckeye.
So, with SCIF, a city like Phoenix could get its normal allocation of SRP water from wells rather than surface water as usual. Then, SRP surface water would be diverted into the CAP canals. Finally, Phoenix would be able to withdraw the equivalent amount of CAP water out for itself to service somewhere outside the SRP service area.
Or for an outlying community like Queen Creek, which isn’t in SRP’s service area; if the municipality has water credits, users within SRP would get their water from wells and SRP would divert the equivalent amount of surface water to Queen Creek through the CAP canals.
Currently, CAP can deliver water to SRP, but not the other way around. The existing mechanism is from 1990 and is called the Central Arizona Project/Salt River Protect Interconnection Facility (CSIF).
The reason the CSIF only works one way is gravity. CAP is at a higher elevation, which means SCIF needs new infrastructure to pump water into the CAP canals.
Next steps
The National Environmental Policy Act (NEPA) process to evaluate potential impacts of the project is expected to start next year. But SCIF isn’t scheduled to be finished until 2030.
The water quality in the CAP system is different from the quality in the SRP system. Rodriguez said stakeholders including CAP and the federal Bureau of Reclamation recently finalized a water quality guidance document for the project.
“There's a delivery and an introduction standard in the water quality guidance document that we would be using as kind of our guidance and ensuring that we're meeting those water quality standards,” Rodriguez said.
The joint project between 14 providers, utilities and municipalities is still a few years away from being built. It will cost an estimated $247 million.
The federal government allocated $154 million to the project through the Inflation Reduction Act at the beginning of the year.
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SRP says varying releases will continue for the next few weeks to balance the water supply between the reservoirs after recent storms.
