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Recycled city water for farms?

Manteca leaders want to explore the possibility

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Recycled city water for farms?

Manteca’s treated wastewater one day could go to South County farms.

HIME ROMERO/Bulletin file photo


POSTED April 16, 2014 12:43 a.m.

Water Manteca residents send down the drain could one day help irrigate South County crops.

Manteca Councilman Steve DeBrum convinced his colleagues Tuesday to have staff explore working with the South San Joaquin Irrigation District to see if 7 million gallons of treated wastewater the city releases back into the San Joaquin River could instead be diverted for local farm use.

Mayor Willie Weatherford believes 100 acres designated for open space as part of the 1,471-home Trails of Manteca neighborhood  being pursued south of Woodward Avenue  and west of McKinley Avenue could be used to create a large holding lake for treated wastewater. From there, the SSJID could pump it into its delivery system serving  farmland south of the city. At the same time, the manmade lake could also help recharge underground water tables that ultimately are tapped by Lathrop and Manteca municipal well systems.

“The water is just going into the river,” DeBrum noted.

The city’s treatment plant processes enough water to support 90,000 people — the current population  of Manteca and Lathrop that send wastewater to the facility.  City ratepayers pay nearly $2 million a year to treat it — including $1.2 million in power costs. It is simply given away free to downstream users.

State law gives cities the ability to sell “rights” to the fresh water they create from the treatment of wastewater. Other valley cities have taken advantage of the law to either sell recycled water for agricultural irrigation or trade it for upstream water.

Manteca could get anywhere from $100,000 to $400,000 a year selling that water by the acre foot depending upon the market and water conditions.

But that isn’t where the real money is.

If Manteca-Lathrop reuses the water it would continue to assure economic prosperity in drought periods or as continued growth and demand outstrips available water supplies.

Treated wastewater is now at such a high quality for cutting edge plants such as the one serving Manteca that some Californians are already drinking and showering using treated wastewater.

That’s been the case in San Diego since 2012 when a pilot treatment plant went into operation that put a portion of San Diego’s treated wastewater through one additional treatment process. The $13 million plant now produces a million gallons of water a day for municipal use to support the equivalent needs of 12,825 people. By 2020, San Diego expects to have 7 percent of all municipal water for drinking as well as other residential and commercial uses come from the city’s wastewater treatment plants.

Treated wastewater has been used for years on crops such as lettuce in the Salinas Valley, for manufacturing processes that require highly clean water, and to irrigate golf courses in Palm Springs.

Orange County has used a slightly different approach. They are injecting treated wastewater directly into the underground aquifer that communities in the region pump water from for domestic use. The recharging already accounts for 20 percent of the aquifer’s water.

DeBrum sees the water being returned to the San Joaquin  River as the equivalent of Manteca tossing away money. He also believes the city should make every effort to help make sure there is adequate water for local agriculture given how SSJID has worked to secure and protect water rights for municipal use.

Weatherford believes the SSJID would be open to such an arrangement.

Turlock in January started exploring selling some  of its highly treated wastewater to the Del Puerto Water District for farm use.

Lodi in 2009 inked a deal with the Northern California Power Authority to buy recycled wastewater for a natural gas power plant. It represents $1 million annually for the city.

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