By volume, the Yuma Desalting Plant is one of the largest in the United States.
Completed in 1992, the plant is owned and operated by the U.S. Bureau of Reclamation with the capacity to filter 73 million gallons of water per day.
It's only been used twice.
To understand why you have to go back to 1944.
In February of that year, the U.S. and Mexico signed a treaty that dictated Mexico was entitled to 1.5 million acre-feet of Colorado River water since that is where it actually ends.
Mike Norris, manager of the USBR Yuma Area Office said over the years as agriculture increased in the Yuma area, so did overly salty return flows or brackish water.
The salty water would go into the river and be delivered to Mexico.
By the 1960s, Mexico demanded better quality water.
"Mexico said 'timeout United States, we should have the same quality of water, as you have in the U.S. to do agriculture and utilize,'" Norris told ABC15.
The Yuma plant was supposed to be part of the solution.
If the U.S. could not meet its obligation, the plant would make up the difference by cleaning some of the brackish return flows and deliver useable water to Mexico.
"As a last case, last ditch effort in case all other avenues don't work," Norris said.
Construction began in 1977 at a cost of $250 million. With inflation, the cost would be just over $1 billion in today's currency.
During the 15 years that the plant was under construction, the salty water needed somewhere to go, other than the river.
The Wellton Mohawk canal near Yuma was extended to divert the unusable water away from the Colorado.
The endpoint of the canal accidentally created Cienega de Santa Clara, a 15,000-acre-foot wetland in Mexico.
By 1992 when the plant was completed, Norris said it was not needed.
"We were in surplus flows (of the Colorado River), there was not a need for the plant at that time," he said.
As a result, Congress reduced appropriations to an amount only to maintain the plant in a standby status.
And that is where the plant has remained for most of its 30-year existence.
Since its opening the plant has run twice: a three-month demonstration in 2007 and a pilot run in 2011 funded by Central Arizona Project, with California and Nevada water agencies.
As the current drought drags on, we asked Norris if the dormant plant could finally be put to use.
He said there are some significant challenges to overcome, including the age of the technology and cost.
"Approximately $40 million on an annual basis just to operate it. And that's not including $230-plus million to get the plant up to operational status," Norris said.
Then there's the Cienega de Santa Clara.
Mexico has declared it a protected area and home to endangered sea life and migratory birds.
Norris said restarting the plant could damage that with even more excessively salty water.
"You want to want to explore all other options, before you start looking at possibly impacting a wetland in Mexico," he said.
So, the multi-million-dollar plant sits idle as it has for the past 30 years waiting for a day that may never come.
