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Council ponders using firm to market treated wastewater
Manteca could turn wastewater into money. - photo by Bulletin file photo

Manteca is sending what could be in excess of $2 million down the drain.

It is water used to take showers, wash dishes, clean clothes, and flush toilets that the city spends several millions of dollars each year treating to the level that it is OK to return to the San Joaquin River where most of the time it is cleaner than the water it joins.

Now the City Council is being asked to explore the feasibility of selling treated wastewater.

When they meet Tuesday at 7 p.m. at the Civic Center, 1001 W. Center St., the council is being asked to authorize City Manager Tim Ogden to sign an exclusive negotiation agreement with the Public Infrastructure Group.

The firm — at no cost to the city — would determine if there is a way to monetize the city’s wastewater that is now being discharged to the San Joaquin River. They would secure consultants and law firms to determine if it is feasible to do so.

“Historically, efforts to monetize or sell wastewater that is currently discharged to the San Joaquin River were considered unlikely due to water rights and environmental concerns,” Public Works Director Mark Houghton noted in a report to the council. “However, new laws related to recycled water have passed recently which may make it more likely that the City could benefit from such a proposal.”

The market for water in California is volatile, to say the least. Drought, location, and supply all play roles in pricing especially on the spot market where prices in recent years have ranged from $100 to over $1,1000 an acre foot.

Many contactors — especially agricultural customers — are willing to enter into long-term agreements for water at costs above the market when a deal is inked to assure deliveries. That is especially true for crops that take a long time to get established such as grape vineyards and almond orchards.

Given Manteca processes an average of 6.5 million gallons of wastewater daily, in a given year they would generate 7,280 acre feet of water. That is enough to meet the needs of 21,141 acres of California’s most profit crop — almonds. The majority of the state’s almond growers do not have as secure water as those within the South San Joaquin Irrigation District. Being able to enter into a long-term water deal would be highly desirable for such growers. Altogether California has more than 1.3 million acres planted in almonds.

If the price of recycled water sold by Manteca was $300 an acre foot that would reflect a gross source of revenue of $2.1 million a year.

It is money that — after costs of executing the deal and delivering the water — would go toward keeping the cost of municipal wastewater treatment down in terms of what is passed on to ratepayers.

It also would be less expensive to put in place than a purple pipe system to deliver treated wastewater to parks and other areas of extensive landscaping in Manteca. 

In some cases water that is non-potable from higher water tables could be used for landscaping as is done at River Islands that also will be mixing in recycled wastewater.

In the past when the city has talked about exploring the selling of treated wastewater some have questioned the wisdom of such a move as it would deny the city a source of water during periods of extended drought when supplanting more expensive treated drinking water with recycled wastewater may be in the city’s best interest. The city has indicated around half of all water used in Manteca is for outside purposes with most going to irrigate lawns.

Other cities in the region have made deals to sell treated wastewater that often times involves the end user simply paying for the treated wastewater sent into the river and pumping it out at a point downstream. Some cities have piped treated wastewater to users.

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

Under terms of the proposal by Private Public Infrastructure they would determine and define the permitting conditions by various agencies, additional treatment requirements, conveyance routes and facilities, potential buyers and terms of purchase, project cost, and a construction schedule

If a project is determined to be financially feasible, the council action would allow PPIG an exclusive right to negotiate a purchase and sales agreement of the City’s wastewater.  To accomplish that, PPIG would come back to the City with a proposal on the project and council would then have the option to proceed forward with completion of the proposed project.   

At that time the firm would arrange private financing for  the project, pay the city for all associated costs including staff time, negotiate a split of revenues with the city for a defined period which includes paying project financing costs, and dedicate privately constructed facilities to the city.

Council directed staff

to explore possibility of

selling treated wastewater

 to SSJID for farm use

Back in April of 2014 council directed staff to explore working with the South San Joaquin Irrigation District to see if treated wastewater the city releases back into the San Joaquin River could instead be diverted for local farm use.

Salinity issues were raised as a major stumbling point. Too much salt in water can kill plants and trees as well as render soil infertile over an extended time. Treated wastewater has a relatively high salt content.

State law gives cities the ability to sell “rights” to the fresh water they create from the treatment of wastewater.

It was estimated in 2014 that 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.

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 by just adding one more step in the treatment process.

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.


To contact Dennis Wyatt, email