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SSJID may harvest run-off

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Two boys run into water backed up in the Cotta Park storm retention basin along Mission Ridge Drive in Manteca following a downpour several years ago.

HIME ROMERO/The Bulletin/

POSTED August 22, 2016 12:47 a.m.

The days of storm runoff from Manteca running into the San Joaquin River then either out into the Pacific Ocean or into the California Aqueduct to feed faucets in Los Angeles could one day be greatly diminished.

The South San Joaquin Irrigation District has started exploring the use of storm water collected in over 50 storm basins in Manteca to recharge water tables as part of a strategy to achieve groundwater sustainability as mandated by Sacramento. 

Manteca — that has 17.76 square miles within its boundaries — receives 14 inches of rain in an average year. Assuming eight square miles drain into the SSJID system it would represent a potential to capture and recharge water tables with upwards of 71,620 acre feet of water in a given year. A football field is an acre which means an acre foot of water would cover a football field an inch deep. That is enough water for the yearly needs of well over 6,000 households. 

The mandate would require local authorities to implement a groundwater management plan that essentially during a set 12-month period achieves a balance between water pumped out and water that subsequently replaces what is used.

Currently storm water from neighborhood streets and other developed areas in Manteca is dumped into the various retention basins strategically placed throughout the city.  Water is held in the basins until such time there is adequate room in the SSJID irrigation canals that double as Manteca drainage canals during the rainy season. 

A telemetry system monitors all of the retention basins in Manteca as well as the canals to make sure the system isn’t overwhelmed.

Once in the canals the water flows to outlets to the San Joaquin River. The primary outlet is the French Camp Outlet that runs immediate east of the Union Pacific Railroad tracks that serve as the Manteca-Lathrop city limits. The water is carried north where is eventually is dumped into the river near Weston Ranch.


SSJID looking at possible

14-acre recharge basin

The SSJID is looking at acquiring a triangle-shaped 14-acre recharge basin on the southeast corner of where French Camp Road crosses the French Camp Outlet in the semirural community of French Camp about 1.5 miles west of Airport Way at the extreme northwest corner of the district. It is near the area where canal overflow is sent into the French Camp Slough during irrigation season.

Bologna said the site is ideal as it would recharge the aquifer than the City of Manteca as well as others within SSJID’s jurisdiction pump water form. That would allow storm water to eventually be taken from underground via the city wells operated in conjunction with treated surface water deliveries the city receives from the SSJID.

 “Manteca saves a lot of expense by using the canals to get rid of storm water,” SSJID Engineering Department Manager Sam Bologna told the Manteca Rotarians meetings at The Rendezvous Room at Ernie’s earlier this month.

By piggybacking on the SSJID canal system, the city avoids the cost of putting in drains to reach the river.

Bologna said the SSJID is starting to explore ways that the storm-runoff from Manteca could be used to recharge the water table hat both the city and nearby rural residents and farmers rely on.

It is one of the reasons SSJID has pushed for upgraded monitoring equipment at the storm basins operated by the City of Manteca. Not only would it provide critical data needed to verify how much water is being captured to recharge water tables but it would establish “ownership” of the storm water.

Who controls what water and how much will play a key role as the California water squeeze is exacerbated by fish flows, continuing drought, and groundwater sustainability mandates form Sacramento.

Manteca is also looking to reuse treated wastewater for landscape irrigation and groundwater recharge as well. A $12 million infrastructure project now underway for the family entertainment zone wets of Big League Dreams would provide a crucial purple pipeline link between the wastewater treatment plan and the existing main sewer line that relies on forced flows provided by pumps powered by electivity. Once the final segment of a parallel gravity line that has been put in as development occurs is in place, the city plans to clean out the forced line and repurpose it for gravity flow of irrigation water to reach areas such as Woodward and Antigua parks as well as Veirtas and Woodward schools.

The SSJID has already taken steps to help stabilize groundwater in the southwest portion of the 72,000-acre district with the Division 9 project west of Ripon and south of Manteca.

The state-of-the-art pressurized deliver system has allowed farmers to stop using expensive pumps to irrigate corps and such to 100 percent surface deliveries. Salt water intrusion had become a problem in the area. The project sustainably increased available water and helped reduce overall water use by 10,000 to 20,000 acre feet a year.

The SSJID is working toward joining forces with the cities of Manteca, Ripon, and Escalon — all three of which are located within its boundaries — to become a groundwater management sub- basin.

Such a partnership would focus on the overall impacts of SSJID switching more of the district to the Division 9 pressurized delivery system given that flooding almond orchards plays a significant role in recharging urban water tables in Manteca and Escalon.


To contact Dennis Wyatt, email



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