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Water supplies tighten
SSJID: 20% cutback for Manteca, Lathrop & Tracy
SSJID is ending its irrigation season Sept. 30. - photo by HIME ROMERO/The Bulletin

There is less water than previously thought available from New Melones for South County farmers and municipal users in Manteca, Lathrop, and Tracy.

The situation is prompting the South San Joaquin Irrigation District to impose a mandatory 20 percent cutback on water deliveries in August and September to the three cities based on the water they received for the same two months last year. The district is also ending the irrigation season for farmers on Sept. 30 instead of the usual mid-October end date.

The SSJID had asked for the cities to voluntarily reduce their draw from the surface water treatment plant by 20 percent back in February. Lathrop reduced their water draw by 16 percent and Tracy by 14 percent. Manteca actually increased their draw of surface water by one percent.

To meet the mandate all three cities will have to step up groundwater pumping. Experts were already predicting a 20-foot drop in the water tables before the SSJID directive was issued. Pumping more groundwater could be problematic for Tracy that already has a serious saltwater intrusion issue. Lathrop is also combating salt in groundwater as the third year of drought has seen seawater push further into the Delta and underground aquifers.

Manteca in June had cut back their overall water use by 20.4 percent dropping down to 502 million gallons from 631 million gallons used in June 2013. It was the first month that Manteca was able to meet the 20 percent reduction for all water users that Gov. Jerry Brown ordered in January when he declared a statewide drought emergency.

The SSJID order means Manteca will have to rely more on its 15 municipal wells.

The SSJID is battling a hard cap of 225,000 acre feet of water it can take from New Melones Reservoir this year. The district last year used 239,670 acre feet and in 2014 consumed 247,070 acre feet of water.

“Because of the hot, dry conditions California is currently experiencing, some growers are taking water at a rate higher than last year,” noted SSJID General Manager Jeff Shields.

The effort to get by 2014 without curtailing water deliveries for agriculture or further reduce municipal water supplies was helped by Tuolumne Utility District’s ability to secure water elsewhere. In March, the SSJID agreed to provide 2,400 acre feet of water to the Sonora community after its main reservoir was depleted fighting the Rim Fire and forecasts anticipated TUD’s water to run out this month. Shields said TUD was able to secure other water sources and only needed to use 100 acre feet.

That reduction coupled with the early end of the irrigation season and the mandatory cutback to the cities will leave the district short 1,616 acre feet. They will make that up by lowering Woodward Reservoir earlier this year and hold the lake level at 204 feet as opposed to the normal 210 feet.

The district is also trying to cover the gap by intensifying efforts to avoid spills from individual grower operations. The SSJID is looking to optimize the use of its own wells to the greatest extent possible. The SSJID will also ask growers that have wells to rely on those for their last irrigation after harvest.

“In talking with almond growers and other farmers it looks like most crops are 10 days ahead of schedule.

Shields cautioned people not to put a lot of hope in El Nino reports. The state last week issued 32 models of what could possibly happen if an El Nino weather pattern does develop. Of the models anticipating a weak El Nino, 29 percent predict a normal rain year and 71 percent below normal. For models anticipating a medium El Nino, 44 percent call for normal rainfall and 56 percent for below normal rainfall. None of the state weather models call for above normal rain and snow in either case. And none of the 32 models predicted an above average El Nino which would deliver high levels of precipitation commonly connected with flood years.

“Normal rainfall and snow would put us where we are at now at this time next year,” Shields said.

El Nino refers to a weather pattern over the Pacific Ocean that develops when warm, nutrient-poor water appears off northern Peru and Ecuador typically in late December. That can often generate wetter water years in California.

Shields said a fourth drought year would pose extremely serious problems for California.

“That said, we (the SSJID) will still be in better shape than most,” Shields said.

The SSJID has water in its upper Stanislaus River reservoirs that it can release into New Melones as part of a carryover conservation account.