Over a decade ago, Southern California water officials rushed to build or expand treatment plants so they could keep up with the demand for drinkable water. That cost hundreds of millions of dollars.
Now demand for water has fallen dramatically. The treatment plants sit largely unused during parts of the year and officials are fighting over how to pay for some of them.
There are two kinds of water: treated water, which has been cleaned up for drinking; and raw water, which comes from a river or reservoir and is not yet fit for human consumption. Water treatment plants make the raw water drinkable.
In San Diego County alone, a dozen major treatment plants can produce up to 830 million gallons of drinking water each day.
Yet even when demand for water was highest – the dry summer months, usually – the county’s plants last year were treating only about 530 million gallons per day of water.
This winter, demand for water was so low that the San Diego County Water Authority temporarily idled a $160 million plant in San Marcos that it built less than a decade ago.
Even then, there was still so much treated water that officials had to dump a half billion gallons  of it into a lake near Chula Vista, making it unfit to drink.
Some of the plants are still being paid off because agencies went into debt to build them. That means even as water use goes down, water rates for some customers will go up.
Mike Lee, a spokesman for the Water Authority, said treatment plants are built to handle high demand well into the future.
“For instance, we don’t build freeways to handle traffic on Sunday morning, we build them to accommodate rush-hour traffic,” he said in an email.
In the early 2000s, the Water Authority had trouble getting enough treated water from its main supplier, the Metropolitan Water District of Southern California.
The Water Authority buys both treated water and raw water and resells it to two dozen local water agencies in the county. Some of those local agencies, including the city of San Diego’s water department, have their own treatment plants, but most do not.
The Water Authority also buys treated water from Metropolitan’s Robert A. Skinner Filtration Plant in Riverside County. Water from that plant is used by San Diego water agencies that don’t have their own treatment plants, as well as two other water agencies in Riverside County.
In summer 2001, Skinner was operating at or above its capacity.
Metropolitan officials began talking about enlarging the plant. At the time, the Water Authority didn’t own its own treatment plant, so it also began talking about building one.
By July 2007, Metropolitan had added 110 million gallons of treatment capacity to Skinner, allowing it to treat 630 million gallons of water per day – roughly as much as everyone in San Diego now uses in a day. That cost about $153 million.
The Water Authority’s Twin Oaks Valley Water Treatment Plant in San Marcos opened less than a year later, in April 2008. The plant can treat 100 million gallons of water per day. It cost about $160 million to build.
Then the recession hit. Then the drought came and Californians used less and less water, both by choice and by order last year of Gov. Jerry Brown.
“At one point in time we didn’t have enough treated water in the early 2000s, now we have too much,” said Gary Arant, the general manager of the Valley Center Water District.
The Water Authority’s own long-term projections tell the story: In 2005, it thought the San Diego region would use about 251 billion gallons in 2020. Now, it’s projecting the need for only about 196 billion gallons in 2020.
Southern California agencies aren’t the only ones dealing with this. The East Bay Municipal Water District in Northern California can treat 375 million gallons of water per day, but treated less than half that on an average day last year.
The unexpected drop could idle the expensive treatment plants in Southern California, or at least parts of them.
Only about 15 percent of Skinner was in use on a recent day. In the past several months, Twin Oaks has been entirely offline at times.
The Water Authority owes $6.1 million in debt payments on Twin Oaks this year and also has to pay $6.8 million to the plant’s private operator, CH2M Hill. The money is due whether the plant is needed every day or not.
Local water agencies have similar issues because water sales are down: They typically depend on selling water to pay for their operations. When people use less water, water agencies sell less, even though many of the agencies’ costs don’t go away.
The city of San Diego has three treatment plants, with a combined capacity of 378 million gallons per day. Peak demand in the summer is about 220 million gallons per day, though average demand was less than 160 million gallons per day.
One of the reasons the city increased water rates  this year is to pay the debts it owes for its facilities, though it’s unclear if those costs are tied directly to treatment plants. A city spokesman for the water department, Kurt Kidman, said he could not say how much debt the department owed on its treatment plants because the plants are part of a “combined number of financed projects that have been refunded and blended together.” The city’s pricing consultant said  it owes $65 million this year to help pay down its overall debts.
The Helix Municipal Water District helps operate a plant that can treat 106 million gallons per day. Peak demand has never come close to that. Lately, daily demand averaged a mere 40 million gallons.
“You have stranded assets and that’s what MWD is facing, just like we are,” said Helix general manager Carlos Lugo, referring to Metropolitan.
Metropolitan’s abundance of treatment capacity has prompted two separate standoffs in recent months with the Water Authority.
First, Metropolitan kept sending treated water to San Diego from Skinner, even though the Water Authority had no need for it. Besides the capacity of Twin Oaks, the Water Authority recently began buying water from a privately operated desalination plant in Carlsbad that produces 50 million gallons of drinkable water a day. Between desalinated water, Twin Oaks water and Skinner water, there was too much water.
In emails sent days before Christmas, the Water Authority’s director of operations and maintenance, Jim Fisher, pleaded with the Metropolitan to stop sending water to San Diego.
“As you are aware, no one anticipated or could have planned for the dramatic demand reductions that all water agencies are experiencing due to the mandatory conservation requirements set by the state,” Fisher wrote to Metropolitan’s head of water system operations.
Metropolitan said it could not stop sending water without making physical changes to its pipeline, which is designed to carry a few hundred gallons of water per second.
Metropolitan also worked on a plan to change how it charges its customers for water treatment.
Metropolitan wanted to collect the same amount of money for treatment costs – $257 million – but its 26 members would pay different portions of that cost. Some would pay less than they otherwise would have, some would pay more, depending on which of several rate plans Metropolitan adopts. The plan is on the back burner for now because of concerns over the formula.
Arant, the Valley Center water official, said that water officials acting in good faith overestimated how much treatment capacity would be needed, but that’s not bad in the long-term.
“You always want a situation where you want to overbuild capacity,” he said. “You don’t want to run out of water, because running out of water is unacceptable.”