Biocycle - Advancing Composting, Organics Recycling & Renewable Energy

Recycled Water saves California Farms

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Courtesy of Biocycle - Advancing Composting, Organics Recycling & Renewable Energy

After studies show no viable microorganisms in tertiary treated wastewater, growers in Salinas Valley now get two-thirds of their agricultural water needs from recycled sources.

RECYCLED water is saving the farm for approximately 75 growers in the Salinas Valley along California’s Central Coast. Because their wells were becoming contaminated with seawater, these growers began irrigating their high-value food crops with recycled water from a nearby wastewater treatment plant. The Monterey (California) Regional Water Pollution Control Agency (MRWPCA) began exploring the feasibility of a recycled water project in the 1980s because of seawater intrusion into well water in the Salinas Valley. Seawater intrusion may occur when groundwater is overpumped from wells in coastal communities. The seawater from the ocean then moves inland through the aquifer and causes salinity problems for farmers and others pumping groundwater near the shore. In the Salinas Valley, seawater had intruded almost six miles inland, making the groundwater too salty for either municipal or agricultural use. Through a water recycling project, the MRWPCA hoped to reduce the extent of seawater intrusion, while providing local growers with a source of higher quality irrigation water. In addition, the agency would be able to reduce its discharge of treated wastewater into the nearby Monterey Bay National Marine Sanctuary.

RECYCLED WATER FOR FOOD CROPS

The Salinas Valley is one of the nation’s top producers of cold season vegetable crops, such as lettuce and broccoli. While state regulations allow for application of tertiary treated water on agricultural crops, it is usually used on crops for animal fodder or for food crops that will not be eaten raw. Because many of their crops are intended for raw consumption, local growers and health officials were concerned that recycled water might contaminate the produce with pathogens. Consequently, health officials directed the MRWPCA to conduct pathogen studies before they would authorize the project.

MRWPCA conducted an extensive study that would ultimately demonstrate that recycled water is as safe as well water when used to irrigate food crops. Released in 1987, the $8 million dollar study showed no contamination from the pathogens tested, which included viruses and fecal coliform, when recycled water was used on a variety of food crops common to the region, including artichokes, lettuce, broccoli, and cauliflower. State and local regulators soon gave approval for use of MRWPCA’s recycled water on food crops. The agency then had the green light to upgrade its plant from a secondary to a tertiary treatment system. While secondary treatment is a biological process resulting in biosolids and clear water, tertiary treatment involves further processing to remove microorganisms and disinfect the water.

CONCERNS OVER “EMERGING PATHOGENS

As the plant was nearing completion in 1997, farmers who were planning to use the recycled water became concerned that it might be contaminated with what they called “emerging pathogens”. These pathogens, which were not included in the 1987 study, included the resistant E. coli 157:H7 strain, Crytosporidium, Giardia, and Salmonella. The growers’ fears were fueled by increasing media coverage of food poisoning incidents related to pathogen contaminated produce, such as the 1996 Odwalla incident involving E. coli contaminated apple juice.

In response to these fears, MRWPCA conducted additional studies to test for the presence of the emerging pathogens. The tests found no evidence of viable microorganisms in the tertiary treated water. These results were released in a report in 1998. The MRWPCA also enhanced its treatment and pathogen monitoring program to further assure the growers. In addition, the agency hired a public relations firm to prepare a media response plan to address any potential crop contamination issues that might be linked to their recycled water.

MISSION ACCOMPLISHED

In 1997, the MRWPCA completed the $78 million reclamation project in partnership with the Monterey County Water Resources Agency. Capable of producing 19,500 acre-feet of water per year, the plant now distributes water to 12,000 acres of coastal farmland.

Delivering the recycled water to coastal farms required construction of an extensive distribution system. The system consists of 45 miles of pipeline, 112 connection turnouts, and serves approximately 75 growers. Pumps connected to the pipeline are identified by bright purple paint and dot fields throughout the region. Growers connected to this system receive approximately two-thirds of their agricultural water needs from recycled water, while well water meets their remaining needs.

To date, the farmers using recycled water seem pleased with the quality of the water. The MRWPCA continues to work with the growers to ensure that the recycled water is suitable for agriculture. Because the recycled water contains salts, the MRWPCA periodically tests soil salinity at farms that are using its recycled water. Chlorine levels of 4-6 ppm have not presented a problem for the farmers.

USE IN ORGANIC FARMING

Since distribution of treated water began in 1997, many growers throughout California, especially those who embrace sustainable and organic farming practices, have expressed an interest in using recycled water. Brian McElroy of California Certified Organic Farmers (CCOF), an independent certifying organization of organic farms, addressed the acceptability of recycled water for use on organic farms at the recent Ecological Farming Conference which is held annually near Monterey. Although CCOF has yet to take a formal stance on recycled water, McElroy stated, “The organic and sustainable farming community has an obligation to assess recycled water because organic is about sustainability.'

CCOF has been certifying organic growers since 1973 and will now begin certifying under the new federal standards on organic agriculture that came out in December 2000. McElroy has concluded that the new federal standards allow for the use of recycled water by default because they fail to address its use. However, CCOF may require stricter growing conditions than the new federal standards. The CCOF Handbook published in 2000 states that recycled water is acceptable only on nonedible food parts.

For example, drip irrigation of strawberries and lettuce is acceptable. However, sprinkler irrigation of these crops is not allowed. CCOF will likely be revising its handbook in the near future in response to the new federal regulations. McElroy had no definitive answers for growers questioning whether recycled water would be allowed. However, he suggested that oversight of the use of recycled water would be “an enforcement nightmare.”

Farmer Lawrence Jaffe expressed frustration at CCOF’s current policy. “There should be one standard for water, no matter the source,” suggested Jaffe, who farms with recycled water in the grape growing region of Sonoma County in California. He feels that recycled water has proven itself safe and that the stigma lies mainly with farmers since consumers do not generally question the source of irrigation water.

While California has a long history of water supply problems, water recycling programs throughout the state are helping to create a solution. MRWPCA’s General Manager, Keith Israel, believes that water recycling will soon become mandated in the not-so-distant future in California. “Water is more scarce than landfill space, and there are laws for mandatory recycling to keep waste out of landfills. I predict there will be mandatory recycling of water in the future.”

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