Manteca is curbing its thirst for groundwater as California moves toward a state mandate to end over drafting of basins within the next 14 to 19 years.

The state mandated Sustainable Groundwater Management Act’s bottom line is basically no more water can be extracted from basins that is replenished in a given period.

Manteca is somewhat better situated to eventually attain that goal than some jurisdictions for three reasons:

*It has been using surface water in addition to groundwater since 2005 when the South San Joaquin Irrigation District surface water treatment plant was completed.

*It has the ability — working in concert with other treatment plant partners — to expand the amount of treated surface water Manteca can use in a second phase expansion.

*It has shifted irrigation of a number of city parks to shallow, non-potable wells.

The shift to non-potable water gets the lion’s share of credit for Manteca using 40 percent less groundwater in 2025 than the city as a whole did in 2014.

The City of Manteca’s 2025 water production report notes 2.194 billion gallons came from wells. That represents 44.5 percent of the water used.

Manteca, since adding surface water to the mix has been using groundwater more extensively in hotter months. By using surface water as the base source for municipal needs and groundwater for to address additional needs especially in non-winter months it has taken some pressure off of groundwater

The surface water is obtained from the South San Joaquin Irrigation District’s rights to 300,000 acre feet of water from the Stanislaus River Basin.

Overall per capita use has been dropping in Manteca thanks to less lawn areas for new homes, more drought resistance landscaping, low-flow toilets and washing machines as well as low-flow showerheads.

Mild and wet weather coupled with wide spread compliance with outdoor conservation rules resulted in Manteca having its lowest April for water consumption in 13 years.

Manteca used 364.8 million gallons of water this past April. That is the lowest April since 2013 when water usage was 352 million gallons. It was also significantly less than in April 2025 when it was at 405.5 million gallons.

Manteca had 25,000 less people — the population was 71,165 in 2013.

The city’s water usage in 2013 for April was 34 percent lower than in April 2003 when residents used 422 million gallons. Manteca had 57,200 residents in 2003.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com