Manteca is dumping 6.5 million gallons of water a day into the San Joaquin River that has the potential to address long-term water needs and help residents weather future droughts.

It’s treated wastewater from the municipal treatment plant.

It is one very expensive process away from being clean enough to drink. That said the level of treatment that still leaves a salinity issue is of high enough quality to be used in landscaping or groundwater recharge.

Manteca, like all cities that pump groundwater, is facing a pending state mandate not to extract more water from the aquifer than it uses in a given year.

And while close to 50 percent of all municipal water used is employed outdoors for landscaping or other uses that means it doesn’t eventually make its way to the wastewater treatment plant, the fact Manteca also is using surface water means there is a good change using treated wastewater for recharge would allow the city to assure groundwater stability.

City looked at selling

treated wastewater

twice in past 7 years

Three years ago the city was looking at selling the treated wastewater to farmers and/or other jurisdictions but a drought once again derailed the proposal.

Back in 2018 at the recommendation of then City Manager Tim Ogden the City Council entered into an exclusive negotiating agreement with Public Infrastructure Group.

The firm was authorized to seek ways to monetize 6.5 million gallons of treated wastewater the city was sending into the San Joaquin River daily via an outfall west of Oakwood Shores. In a given year that comes to 7,280 acre feet of water. That is enough to meet the needs of 21,141 acres of California’s most profitable crop — almonds.

The last drought had just ended and city was looking for innovative ways to generate municipal revenue. The consulting firm —which would not be paid unless a deal was inked — estimated Manteca could realize as much as $3 million annually from such a transaction based on a price of $450 an acre foot.

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

The council at the time was lukewarm to the proposal with Councilman Gary Singh going as far as expressing serious reservations about the rationale of even exploring such a move even if it didn’t cost the city a cent. Singh at the time implied it would be reckless for the city to sell what could one day be water needed in Manteca.

A similar effort by municipal staff four years prior in 2014 to explore selling wastewater was dropped a year later when the drought at that time deepened.

Manteca now spending

$2.7M on master water plan

The city is now embarking on a $2.7 million plus update of its water master plan.

In June the Manteca City Council hired HyrdroScience Engineers for close to $1 million to:

*do an interim water rate study.

*do a final water rate study.

*develop a citywide water masterplan.

*develop a website and use social media to keep the public updated.

When all is said and done the city expects they could spend close to $2.7 million. The remainder of money is needed to prepare environmental, grant, and preliminary engineering documents. Any remaining budget not spent will be returned to the appropriate fund at the conclusion of the project.

The water plan is not expected to address the potential use of the city’s recycled wastewater even though they have required a number of developments to install purple pipe that is used for the distribution of such water.

Manteca for nearly 20 years has toyed with the idea of using recycled wastewater. One includes cleaning out the forced pump sewer main that runs along Woodward Avenue and then swings north to the treatment plant on an alignment between Great Wolf and Costco once the missing link of a parallel gravity line is completed when future subdivisions are built east of Airport Way along Woodward Avenue.

That would allow the forced pump sewer line to be converted into a gravity line to move recycled wastewater for use for irrigation at Woodward Park as well as landscape areas including neighborhood parks in tract developments that were required to install purple pipe in recent years. Other major water users such as school fields that are close to the line could also use the water.

City has added non-potable

wells to irrigate some parks

The city also a decade ago started installing shallow wells at various city parks that tapped into a higher water table with non-potable water not suitable for drinking.

The idea was not to use expensive treated water from the South San Joaquin Surface Water Treatment Plant and the city’s 17 municipal wells that drop down significantly further to tap suitable drinking water.

The new state mandate, however, will count water removed by those park wells as well as at the golf course against the need to recharge the aquifer.

The recycled sale option 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. That is because a deal — had one advanced — would not have cost Manteca anything to implement as the funding would have been with private investment.

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.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com