Conceptually it makes a lot of sense to farmers and oil producers alike: Use the latest filtration technology to turn one of Kern's most troublesome waste streams — oilfield produced water — into a safe irrigation source.

For decades it's been done on a relatively small scale near Bakersfield, and recent studies confirm it doesn't threaten crop safety. So why aren't more local oil producers giving farmers the briny water that comes up from the ground along with oil?

In a word, money. Treating oilfield produced water can be expensive, more so depending where it's from, not to mention the cost of transporting it to a filtration plant and then on to an orchard or field. Oil companies don't want to pay for that any more than farmers do.

People who have examined such arrangements say costs are coming down and it's only a matter of time before produced-water treatment facilities scale up — likely within a decade as freshwater supplies decline.

NOT PENCILING OUT

But as badly as local growers need new water supplies, produced water still isn't cutting it financially for most local ag, the president of the Kern County Farm Bureau said by email.

"Margins are tight within the agricultural industry, and oil produced water hasn't yet been economic," President John Moore III wrote.

Public perception is a separate challenge. Environmental groups have railed against the practice, less so since recent studies in which researchers tested crops irrigated with produced water treated and blended with freshwater. They couldn't find any uptake of hazardous chemicals associated with oilfield operations.

Still, there remains a stigma associated with eating produce grown with recycled oilfield wastewater.

"That's going to drive the market," said the director of water resources at the California Farm Bureau Federation, Danny Merkley, referring to the stigma.

He nevertheless affirmed "great potential" in increasing produced-water irrigation, depending on the region and the commodity being grown. (Some crops are more resistant than others to the boron and salts that produced water contains.)

SURVEY SAYS

A recent survey of Kern County adults found a slight majority were aware of produced water being used for irrigation. A little less than two-thirds were worried for the future availability of usable water.

Responses from 150 respondents surveyed by Cal State Bakersfield assistant management professor Sumita Sarma suggested they were more wary of recycled toilet water and non-oilfield forms of industrial wastewater than they were bothered by treated produced water.

Oilfield produced water has presented challenges for oil companies for generations. It comes up in volumes averaging about 10 times the amount of oil that accompanies it. If oil producers can't properly dispose of that fluid, they can't produce oil.

Salt and boron are the most problematic contaminants found in the fluid locally, and they're the costliest to remove. Toxic chemicals can also be present in small concentrations. Produced water from the east side of the valley portion of Kern County tends to be much cleaner, requiring less treatment than what's found on the west side.

OLD PRACTICES

Historically, local oil producers have separated petroleum from produced water then left the waste to evaporate or percolate into a nearby disposal pit. That practice has largely been phased out because of groundwater quality regulations, and now disposal by injection is more common.

Several years ago concerns arose that local produced-water injection work was contaminating federally protected aquifers. Interest in filtration and irrigation rose. But lately a growing number of aquifers have been declared appropriate for injections, making it less urgent to find disposal alternatives.

Rock Zierman, CEO of the California Independent Petroleum Association, emphasized the produced-water treatment that is happening locally has been limited by expenses including conveyance — construction of pipelines and canals to handle large volumes of fluid. Underground injection is the more efficient, environmentally sound disposal method, he said.

If there's to be greater reuse of produced water in agriculture, he said, it'll have to be initiated by local water districts and growers.

"I think it's going to be more driven by farmers' desire for more water sources," Zierman said.

GRADUAL EFFICIENCY

People in the water filtration business agree that demand from agricultural users will gradually lead irrigation costs higher until treated produced water becomes more economically feasible.

At some point farmers will have to cross what Arian Edalat, president of Los Angeles-based Pacifica Water Solutions LLC, sees as the psychological barrier of agreeing to pay for treated wastewater.

That'll become necessary, he asserted, because processed water will always cost more than freshwater. Maybe regulation will provide the incentive, he said, or perhaps it'll be a creative commercial arrangement.

There's no question the technology is improving, added Edalat, whose company has done produced-water treatment work in Kern but isn't currently operating in the county. Technological progress is to be expected because oilfield wastewater filtration is part of a global push for more efficient desalination processes.

Edalat predicted growing demand will make produced-water treatment commercially viable on a larger scale within two to five years. But it'll take infrastructure investment.

"It's more a commercial development as opposed to technological development," he said.

AG CURIOSITY

Farmer interest at this point appears significant but limited, based on a survey Sarma conducted at CSUB in which 13 farmers participated.

About half supported the use of produced water for irrigation of food crops. Two-thirds were OK with using it to supplement their water supplies, even if just for washing down equipment or controlling dust.

A quarter were concerned about overall water quality, a third about customer satisfaction.

If offered produced water as clean or cleaner than what they irrigate with now, a third said they would be willing to pay the same price as what they pay for freshwater.

Forty-two percent said they'd pay less. A quarter said they'd use the water if they got money in exchange or received some other incentive like a greater allotment of water.

NO MORE THAN A DECADE

Give it five to 10 years, said David Ansolabehere, general manager of the Cawelo Water District northwest of Bakersfield. Cawelo has for decades bought tens of thousands of acre-feet of water per year at a discount from local oil producers then blended it with freshwater for use on food crops.

"I'm sure in the future more people will try to utilize this water, when technology gets a little bit better and more effort is (focused on) how to treat it," he said.

Recent studies have found in favor of the health and safety of using produced water blended with freshwater to irrigate food crops.

For nearly five years the Central Valley Regional Water Quality Control Board took a hard look at fruit and vegetables coming out of fields that used blended, treated produced water from Cawelo. After testing for more than 140 chemical compounds, the agency declared in May its Food Safety Advisory Panel had turned up no red flags.

That same month the journal Science of the Total Environment published a study concluding Cawelo's treated and blended produced water found no major health risks.

"We did not find any major water quality issues, nor metals and radioactivity accumulation in soil and crops, that might cause health concerns," Avner Vengosh, professor of water quality and geochemistry at Duke University's Nicholas School of the Environment, said in a news release. The study was done in cooperation with RTI International.

SOIL ACCUMULATION

The study, funded mostly by the U.S. Department of Agriculture, did find salts and boron had accumulated in soil over time, prompting advice farmers should plant crops tolerant to those chemicals. It noted Kern's produced water is more diluted and lower in salt than other U.S. oilfield wastewater sources.

A local contributor to that study was Luis Cabrales, assistant professor of engineering at CSUB. With a background in materials science and plastics, he started on produced-water filtration technology about seven years ago and is now working with engineering students at CSUB and Fresno State to validate an electro-chemical oxidation process for removing hydrocarbons from produced water.

The technology uses two titanium alloy roads coated with mixed metal oxide and submerged in produced water. They don't remove salts or boron but Cabrales said they efficiently separate out hydrocarbons in a bacteria-killing process suitable for use by oil producers large and small.

His students' investigation requires them to visit a half-acre agricultural field near McFarland daily and check on grass being grown for livestock. The project is in its second year.

NEED FOR INCENTIVES

The company whose technology they're validating, L.A.-based OriginClear, is not currently doing work in oilfields and has changed a lot since it first contracted CSUB's help. But its president, CEO and chairman, Riggs Eckelberry, has put thought into how to make produced-water filtration profitable.

Financial incentives need to be introduced, he said, and the final product must be standardized to certain quality measures in order to be viewed as a commodity that can be traded on the open market.

Maybe what's needed, he said, is a public relations campaign showcasing oil companies' good-neighborliness.

"I think that's the only way to go forward," he said, "because the technology's there."

Follow John Cox on Twitter: @TheThirdGraf