This week’s storm will help bring some relief to water agencies in an unusually dry year, but better-than-average rainfall in the Central Valley and snowfall in the Sierra are needed to avoid a major water crisis.
Fortunately, that crisis doesn’t impact the city of Tracy, which has adequate, multiple sources of water to meet the city’s projected needs during the current rain season, which ends next July.
But in the rural areas, farmers are more vulnerable — and more concerned. A continued shortfall of rain and snow, which started in 2012 and has worsened in 2013, would mean meager irrigation water, or possibly a zero allocation, from the federal Delta-Mendota Canal.
“If we don’t get an average snowfall in the mountains by February, the situation could become dire,” said Frances Mizuno, a Tracy resident who is assistant executive of the San Luis & Delta-Mendota Water Authority, which operates the Tracy pumps and the canal. “Even with an average snowfall, the situation would be grim. We need a wet year.”
Just Wednesday, Nov. 20, the State Department of Water Resources provided an early warning signal of the water situation by announcing that its initial water allocation for contractors securing water from the California Aqueduct was 5 percent.
Most vulnerable to low allocation are districts along the canal that rely solely on federal Delta-Mendota water. That includes land that originally was in the Plain View Water District west of Tracy, now part of the Byron Bethany Irrigation District.
Increased irrigated farming in those districts, including the extensive planting of almond trees, adds to the seriousness of a potential water shortage, Mizuno said.
Districts relying on Delta-Mendota water will be seeking water transfers from other agencies and seeing more water pumped from wells, she predicted.
Two major Tracy-area irrigation districts — Banta Carbona and West Side — have contracts for Delta-Mendota Canal water, but typically acquire most of their water from the San Joaquin and Old rivers, giving them more leeway in meeting their water needs.
If the river flows become extremely low under a worst-case scenario, however, pumping from the rivers could also be impacted.
The San Luis Reservoir, which stores water for summer use in the lower San Joaquin Valley, is at 24 percent of its capacity, and no matter how much rain and snow arrives, it cannot be filled this water year, Mizuno reported.
Meanwhile, the city of Tracy is doing well, waterwise, reported Steve Bayley, the city’s public works project specialist and point man on water issues.
“We have a need for 18,000 acre-feet of water this season, and we have enough capacity from a variety of sources to meet that need,” he said. “We’re in good shape.”
An acre-foot is enough water to supply about 2.5 four-member households for a year.
The city has a municipal and industrial water contract with the U.S. Bureau of Reclamation for 10,000 acre-feet of Delta-Mendota Canal water. The city’s best estimate is that it may receive half of that, but it could be less, Bayley said.
Another major source for the city is a 10,000-acre-foot contract with the South San Joaquin Irrigation District for Sierra runoff water. Smaller amounts come from the Banta Carbona and West Side irrigation districts and purchases from the city of Lathrop.
If any of those sources fall short, the city can pump up to 9,000 acre-feet from an underground aquifer into which the city has been pumping groundwater for the past three years. The city has nine operating pumps, and as many as needed could be put into use, Bayley reported.
Another backup source is a one-time 6,100-acre-foot purchase of federal water allocation from a water district in Kern County, he said.
• Contact Sam Matthews at 830-4234 or firstname.lastname@example.org.