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SSJID farmers, delivery system major source for groundwater recharging
flood irrigatoion
Flood irrigation is shown underway in an almond orchard.

Drive by a flooded almond orchard in the countryside surrounding Manteca, Ripon and Escalon and your first thought might be outrage.

After all, California is slipping deeper into a third year of a devastating drought.

Looks, however, can be deceiving.

What looks like a waste of water is actually helping keep water flowing to your home to wash clothes, drink, flush toilets, shower or bathe, and wash dishes and such if you live in Manteca, Ripon, and Lathrop.

Both cites rely on a combination of surface water from the South San Joaquin Irrigation District and groundwater pumping to meet growing municipal needs.

The thousands of acres that are still flood irrigated in the district  — along with seepage from SSJID canals, laterals and reservoirs — are recharging the groundwater.

Studies have shown in a typical year water diverted from the Stanislaus River by SSJID is credited for recharging the Eastern San Joaquin Groundwater Basin with at as much as 135,000 acre feet of water.  

It is helping counter pumping pressure elsewhere in the aquifer that serves a large swath of San Joaquin County.

 It is why simply banishing flood irrigating as an effective water to stretch water supplies could in a number of areas such as in the South County actually have more negative impacts than good.

Flood irrigation is part of

California water’s Rubik Cube

It is a paradox that water experts trying to solve the California water Rubik’s Cube the California as they try to find ways to stretch water supplies to meet the needs of fish, river ecological systems, urban users and farmers.

There has been a push in recent years to reduce orchard water consumption by eliminating flood irrigation and even sprinklers. Instead, many have advocated pressurized drip irrigation such as the cutting edge system the SSJID has in place in Division 9 south of Manteca and west of Ripon.

But if SSJID eliminated or greatly reduced flood irrigation, Mountain House would currently be distributing water to its residents from tanker trucks at the town center while water tables serving the cities of Manteca  and Ripon would be significantly lower.

It’s because the water Mountain House is receiving from SSJID is part of the 135,000 acre feet of groundwater the district users return to the aquifer via flood irrigation.

It is water that some farmers — as well as those who simply have an acre or two they live on in the country — draw on for their water. It is also water that help replenish aquifers serving the cities of Manteca and Ripon.

The district has several wells that it uses from time-to-time to augment surface water deliveries.


Seepage into SSJID groundwater

made emergency water transfer

to Mountain House possible


Flood irrigation that recharges groundwater within the district is  what enabled the SSJID to bypass the need to secure state approval to send 1,500 acre feet of water in an emergency transfer that started in June to Mountain House after the State Water Project essentially  cut off their water deliveries.

The fact the water transfer is ground water and both SSJID and Mountain House have interconnected waterways, the agreement between the community service district and the irrigation district wasn’t subject to the state’ approval.

That’s not the case with a bid by the SSJID and Oakdale Irrigation District — their partner in the Tri-Dam Project that operates three reservoirs on the Stanislaus River watershed — to enter into a long-term agreement with the Me-Wuk rancheria in Tuolumne County outside of Sonora to provide the struggling community with secure water.

While the proposed  in-basin water transfer is not likely to be tripped up by the state or federal government — a similar deal to help fish flows and Westside farmers was spiked earlier this year by the Bureau of Reclamation — it underscores how what seem like common sense solutions to help California weather the extreme drought that is now in its third year and continues to deepen are often prevented from happening.

At the depth of the last drought, the two irrigation districts made an emergency transfer when the rancheria was within weeks of running out of water.

The 750-acre-footwater transfer adheres to a longstanding policy of both the SSJID and OID to help other jurisdictions within the Stanislaus River basin when are in need of water.

It dovetails into the stewardship investment both districts have made that pre-date state orders to conduct research on ways to improve Chinook salmon populations on the Stanislaus River that includes enhancing salmon spawning areas.

The deal that actually will mean SSJID is dipping into only 375 acre feet of their half of 600,000 acre feet of water rights on the Stanislaus River they share 50-50 with OID was postponed last week due to new regulatory concerns that need to be addressed.

The Me-Wuk’s Chicken Rancheria has made enhancing their water system and having an adequate water supply a top priority after running perilously close to the spigot running dry in recent droughts.

They have also secured a $3.6 million state grant to install a 400,000 gallon water tank, replacing aging lines with 10,500 linear feet of 8-unch pipe as well as install 15 more fire hydrants.

It is all part of an effort to assure the community doesn’t run out of water and has water available to fight fires.


Woodward Reservoir’s soil

makes it a big water sieve

Woodward Reservoir was a great place 106 years ago to build an in-district storage facility to allow for the gravity delivery of water. But the soil is less than ideal to minimize percolation, making it a gigantic sieve to replenish groundwater.

That said an equally important — if not more so — source of water to replenish groundwater is deep percolation from flood irrigating.

There is 134,000 acre feet of water that SSJID — not by deliberate design — annually rechargers the aquifer based on a 2018-2019 study. In the same year the district, as well as farmers within the SSJID boundaries plus rural homeowners, pumped 65,000 acre feet of water from the basin.

That leaves 69,000 acre feet of water SSJID recharges the ground with to head north and west to help replenish what cities and out-of-district farmers that rely in well pump out of the ground.

Manteca and Lathrop — unlike Stockton, Escalon, and Ripon — rely on both SSJID water and well water to meet municipal needs and therefore aren’t 100 percent at the mercy of groundwater as the other three cities are.

Even so, Manteca’s 15 municipal wells, depending upon how the system is operated in a given year, can draw between 5,000 and 7,000 acre feet of water from the ground.

Storm runoff in Manteca has a minimal impact on recharging the water basin the city relies on. That’s because it is collected in basins, released into SSJID canals and drained into the San Joaquin River.

Manteca, once surface water became available in 2005, has operated its system to keep costs down and to try and minimize impacts to groundwater. The city tries to operate 100 percent on surface water in the winter and brings all wells on line in the summer.

Agricultural and municipal wells in the basin go down 80 to 800 feet with the typical well dropping down to 350 feet.

 Environmentalists for years would take one look at an almond orchard being flood irrigated and condemn it as a wanton waste of water.

Such irrigation techniques have become a whipping boy of sorts for those dedicated to securing more water for fish.

It is also a convenient target for urban interests that paint agriculture that feeds everybody as needing to be more frugal before cities are required to cut back on water use during droughts. It is also a bone of contention even in normal years when the issue is the fact more water has been committed on paper to be delivered to California’s cities and farms than the state’s hydrology can provide.


Need to stabilize groundwater

prompts a different look at

benefits of flood irrigation


The advent of the state mandate to stabilize groundwater has prompted scientists and researchers to look at the impacts of flood irrigation differently.

The Sustainable Groundwater Management Act that requires a plan in place by 2025 to work toward taking no more water out of a basin than is recharged in a given year. The SGMA mandate must be fully implemented by 2040.

The Eastern San Joaquin Groundwater Basin that the SGMA mandate applies to extends to the San Joaquin River in the west, the Stanislaus River in the south, the base of the Sierra foothills in the east and the Mokelumne River in the north.

In 2016 at the height of the last drought, University of California at Davis scientists started an experiment to see if deliberately flooding almond orchards during the winter when they are dormant and excess storm runoff can be diverted onto them would be an effective way to re-charge groundwater.

One test site was a Modesto orchard owned by almond grower Nick Blom. It was selected due to the soil type that is conducive to percolation and the fact the aquifer is 45 feet below. In times of drought when delivery cutbacks are imposed for surface water from Modesto Irrigation District Blom turns on his wells.

Whether almond orchards can help California make major headway into its chronic groundwater over drafting hinges on the outcome of research.

That includes whether the roots sustain damage or disease from flooding orchards when the trees or dormant. There is also the question of modifying fertilizing so nitrates don’t become a big issue in groundwater.

If using winter storm runoff in almond orchards is found to be an effective and a safe way to recharge groundwater, researchers estimate there are 3.6 to 5.6 million acres of almonds with conducive soil that could be used for recharging purposes in California.

It could be a fast and effective way at getting excess winter water flows that end up in the Pacific Ocean to recharge aquifers.

It is also less expensive that creating recharge basins that are being explored in San Joaquin County and throughout California.

Other UC Davis tests on grapes, alfalfa, and pistachios showed flood irrigation did not harm those crops or impact drinking water.


To contact Dennis Wyatt, email