If you’re a Central Valley farmer and haven’t yet been hit up by someone about reusing crummy water for irrigation — just wait.
Companies are springing up all over with the latest gizmo they believe will take nasty, salty water, mostly from shallow aquifers on the valley’s west side or oilfield produced water, and make clean “new” irrigation water.
It’s true, there are ways to clean even the worst water.
Reverse osmosis, pushing water through a membrane, will take care of most salts and nitrates. And there are a host of other methods, including ion exchange, evaporation, chemical-electro processes, compression, ozone, bacteriological, etc.
Each has its pros and cons, but two big questions always remain: What about the waste? What’s the energy cost?
Well, as they say, if you have to ask, you probably can’t afford it.
Reclaiming poor quality water has become an especially hot topic in the San Joaquin Valley as agricultural water users scramble to meet a new state mandate to bring severely over-pumped groundwater basins into balance.
That will require reducing demand by fallowing potentially huge tracts of farmland or finding new sources of water.
Hence, there’s been a burst of interest in whether poor quality water can be made clean enough for irrigation.
“There’s been a lot of commercialization popping up in this area,” agreed Sarge Green, a water management specialist with the Water and Energy Technology Center at Fresno State University.
So far, he said, the processes and devices he’s seen come through the WET Center, which provides testing facilities and acts as a business incubator for viable companies, all have the same “weak links” — energy and waste.
“The more novel companies are finding ways to get the energy costs down,” Green said of projects he’s looked at. “But the salts are difficult. Anything above 10,000 TDS (total dissolved solids, mostly salts) is really difficult.”
Scale is another issue.
There are a lot of water reclamation concepts coming out of the oil industry, Green said. For every barrel of oil, about 10 barrels of mostly unusable water are pumped up as well. All that water has to be disposed of properly.
That could create a natural synergy. Oil companies need to get rid of water and farmers need all they can get.
Except, “Some companies are saying they can clean 10,000 barrels a day,” Green said. “Well, one barrel in oilfield parlance is 42 gallons or 420,000 gallons a day. That’s only 1.2 acre feet and 1.2 acre feet a day in a large agricultural area is nada, nothing, no value at all.”
New water, same regs
Beyond those issues, water managers still have to adhere to the mandates of the Sustainable Groundwater Management Act even when tapping “new” sources of groundwater, warned Jason Gianquinto, General Manager of Semitropic Water Storage District in north western Kern County.
With an overdraft of up to 165,000 acre feet a year, Semitropic has one of the largest groundwater deficits of the ag water districts in the Kern subbasin, which has an overall deficit of nearly 300,000 acre feet per year.
“We’ve been looking at this for a while,” Gianquinto said of reclaiming brackish water from shallow aquifers on the valley’s west side. “We know it’s there, but is it a new water supply? Potentially. Is it exempt from SGMA?
“No,” he continued. “You still can’t pump it and create undesirable results.” Those include chronic lowering of the water table and subsidence, among others.
Even brackish groundwater has to be accounted for and potentially replenished.
“And the salts, what do we do about that? No one’s really cracked that question,” Gianquinto added.
The salt conundrum
There have been piecemeal efforts by universities and different government agencies over the years to find that answer.
The Department of Energy is funding what is hoped will be a more cohesive effort among universities and private industry, said Karl Longley, chair of the California Regional Water Control Board and a retired professor who founded Fresno State’s California Water Institute.
Through that funding, the Lawrence Berkeley National Lab is creating a roadmap of water research projects and private/public partners to work on these and other water issues, Longley said.
“What I’d like to see is for the California Legislature to get its hands around this and establish a research division under the State Water Resources Control Board to pour money into the science and solve some of these problems,” Longley said.
The California Air Resources Board has a scientific division, he noted. Water needs to have a similar research and testing arm with state oversight.
“There are a lot of folks in the private sector, working in this area and if we had a panel, with testing facilities that could run quality tests, it would be easier for companies whose science seems to be good, to test their theories,” he said.
Right now, companies with water clean-up concepts have to prove their technology independently, usually by having an oil company or water district fund a pilot project.
There really isn’t any upfront state oversight.
“We get a lot of calls on this,” said Clay Rodgers, director of the Central Valley Regional Quality Control Board. “We don’t do proof of concept or write recommendations.”
The board gets involved when a project is set to start. That’s when operators need to apply for a permit to use the reclaimed water, which is wastewater. And if there’s any residual material left after the water’s been cleaned — usually salt — that needs another permit for proper disposal, Rodgers explained.
He’s seen and heard of a lot of water reclamation concepts over the years and the bottom line is, if the salt level is too high, the cost to clean it is just pricey for ag.
“Oh yeah, we get lots of calls. Sometimes weekly,” said Russ Freeman, Deputy General Manager of Water Resources for Westlands Water District.
One of Westlands’ biggest issues is what to do with salty water that drains off its growers’ fields.
“Everybody looks at that and says, ‘We have the solution,’” Freeman said.
But once you factor in the cost of treatment and disposal, not to mention collecting the drainage water from various fields, the per-acre price is likely above $1,000.
That might work for some growers in a dry year. But with prices at $180 to $240 an acre foot in normal to wet years, water treatment prices can’t compete.
“So, their method might be technically feasible, but it’s not practical,” Freeman said.