- Recycled Wastewater Used
to Irrigate Crops in California
- By Lisa Lieberman
California Correspondent
- In California, where the saying “whiskey’s for drinking and water’s for fighting”, is no laughing matter; having a consistent supply of water is becoming increasingly important to farmers.
Within the next 20 years, the population is expected to double, and with intermittent droughts, the water supply is going to become tighter and tighter. As a result, California water users have been looking into creative new ways for irrigating their farmland. A good example of this is in Monterey County where salt-water intrusion from the nearby ocean has been getting worse over the past several decades. About 70% of the nation ‘s salad ingredients come from this part of California.
In answer to the growing problem with salt-water intrusion, the Monterey Regional Water Pollution Control Agency (MRWPCA) in Salinas, has coordinated a project to irrigate 12,000 acres of row crops and strawberries with recycled wastewater from the Salinas area.
While irrigating landscaping and cotton crops with reclaimed wastewater is nothing new, many farmers are just beginning to see the benefits of using recycled water for food crops.
“Everyone thought we were crazy at first, but technology has become so advanced, that recycled water is actually safer than drinking water,” Jefferson said.
Jefferson said that farmers in the 12,000-acre project use about 70% of reclaimed water from the MRWPCA for irrigation along with 30% of their well water.
Initially there were some problems with using the reclaimed water in the soil, such as excess deposits of sodium and chlorides, Jefferson said.
“But we counteracted that with different commercial (products) and we used gypsum instead of lime and more organic composts to help break down the soil,” Jefferson said.
The heavier amounts of nitrogen in the water, however, decreased the soil’s need for fertilizer by about 5%, Jefferson said.
In terms of yield, crops grown on soil irrigated with recycled water did just as well or better than vegetables irrigated with regular well water, said Bahman Sheikh, a water reuse specialist who consulted on the project. “In some crops such as celery, broccoli and cauliflower, yields were as much as 20 percent higher. The fact that nitrogen and phosphorous are recycled in the water and are continuously present may help the plants grow better,” Sheikh said.
Although yields in some cases might have been better than average, the cost of the recycled water was more expensive - about $250 per acre foot compared to a cost of $75 per acre foot pumped from the wells.
“But when you think of the possibility of not being able to farm at all (because of salty well water), $250 per acre foot is pretty cheap,” Jefferson said.
Saltwater intrusion in the Salinas area has been an ongoing problem since the 1940s, Jefferson said. “At its peak, it was moving at about four feet a day,” Jefferson said.
Since the start of the Monterey project, saltwater intrusion has become much less of a problem on the 12,000 acres since farmers are having to withdraw less water from the aquifers, said Bob Holden, the water recycling coordinator for MRWPCA.
“The recycled wastewater has helped slow seawater intrusion (in the project area) 30 to 40 percent,” Holden said.
While the economical and environmental benefits of using reclaimed wastewater made sense, one of the biggest challenges Monterey project participants feared was public perception.
“The Achilles’ heel of the project was the consumer perception that the recycled waste water (used in the fields) would have been sewage just 11 hours earlier,” Sheikh said.
Some farmers on the 12,000-acre project area also feared that consumer perception might slow sales to buyers. However the science of the project and the independent third party testing of the water and the soil seemed to reassure retailers and buyers, Jefferson said.
Also, the fact that the government doesn’t require growers to specify the use of reclaimed wastewater on their labels, seemed to limit overall consumer awareness of the project.
One of the biggest challenges MRWPCA thought they would face at the beginning of the project, was gaining the trust of the local consumers around the immediate project area, Sheikh said.
“During the first year of the project, we didn’t allow any produce to be consumed. We supervised truckloads of lettuce, artichokes going straight to the dump,” Sheikh said.
After doing extensive testing the first year and determining the produce was safe, the second year members of MRWPCA began taking produce home to their families.
“My colleagues were convinced this was safe and started consuming. To us, this was the biggest test. Folks are reasonable, they won’t touch something that they know is not safe for them.”
Ultimately, as consumer acceptance of recycled wastewater on food crops grows more widespread, more farmers will most likely use it as a water source, Jefferson said.
“I think this is the wave of the future in coastal areas where people are having problems with salinity. There just aren’t that many other choices,” Jefferson said.
