More water is rushing down the Stanislaus River today accelerating the draining of New Melones Reservoir and raising the prospect that South County farmers may run out of water before Sept. 30.
The Bureau of Reclamation — after indicating they would cut back releases from 250 cubic feet per second (cfs) to 200 cfs — on Tuesday instead directed releases to increase to 350 cfs to combat salt water intrusion at Vernalis south of Manteca on the San Joaquin River.
“That kind of operation is guaranteeing we will have to empty or lower Lake Turlock Lake,” said South San Joaquin Irrigation District General Manager Jeff Shields. “We won’t be able to manage Lake Tulloch as a full reservoir if the Bureau is emptying New Melones this early in the season. The message that we’ve got to get out to our community, our farmers, and the people at Tulloch Lake that as long as the Bureau operates the reservoir the way they are, the chances of us making it through the summer continues to diminish every day they do this.”
The Bureau move Tuesday flies in the face of dire projections the federal agency made the day prior for water flow projections from New Melones through the end of 2015.
Numbers released by the Bureau on Monday shows that New Melones Reservoir will for all practical purposes become a dead lake sometime in August when it reaches the dead storage point of 80,000 acre feet or just over 3.5 percent of its design capacity of 2.4 million acre feet of water.
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New Melones projected to drop to 2 percent of capacity by October
Dead storage refers to water that cannot be drained by gravity through the dam’s outlet, spillway or power plant intake and can only be pumped out. The projection calls for the reservoir to dip to 49,000 acre feet or 2 percent of capacity by Oct. 1. It is projected to stay below dead storage through at least Jan. 1 when 63,000 acre feet of water is expected to be in the reservoir.
While the data had no footnote saying how river flows would be maintained, the only way the Stanislaus would still have water in it is if the Bureau pumped it out of New Melones and into the Stanislaus.
Operational projections for New Melones and other Central Valley Water Project reservoirs released by Bureau reflect the severity of California’s fourth year of drought. It is based on data gleaned on Feb. 1. Since then, February had failed to meet even last year’s precipitation. The four-day storm that was supposed to end the month was a bust in many places on the Stanislaus River watershed leaving only traces of rain in Manteca and in the Tuolumne Utility District that is in significantly worse shape than many other areas of the state.
It further underscores the South San Joaquin Irrigation District decision last week to declare a water emergency.
The SSJID board also:
• Capped farm irrigation deliveries at 36 inches essentially instituting a mandatory 16 percent cutback.
• Told the cities of Manteca, Lathrop, and Tracy that surface water deliveries will be cut 20 percent indefinitely starting April 1. That’s opposed to last year when 20 percent voluntary reductions were in place only for July, August, and September.
The SSJID along with Tri Dam Project partner Oakdale Irrigation District last month outlined plans to significantly lower or drain Tulloch Lake to keep more water in New Melones if water runoff projections for the Sierra snowpack hold true. It is designed to keep water temperatures critical to fish from spiking significantly. It is a mirror of a successful strategy used during the 1991 drought.
That reflected the drought getting worse with a poor March rainfall and snowfall. The Bureau’s action Tuesday, though, could set the stage that even if March precipitation improved the districts would be forced to lower or drain Tulloch regardless.
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Bureau underscores consequences of losing cold water pool
That’s because ultimately fish need to be kept alive under the Bureau’s operating plan. And as senior water right holders on the Stanislaus River OID and SSJID could face serious consequences from the federal government and/or the courts if they don’t do everything within their power to keep fish alive.
The key fish issue is water temperature for Chinook salmon. As the lake drops, the pool of cold water critical for the salmon starts getting smaller.
According to the Bureau’s website for New Melones when the lake lowers, the old dam, now submerged, prevents cold water at the bottom of the lake from reaching the outlet works of the new dam. Thus, temperatures are too high for the fish downstream from the dam. The situation becomes most critical when the amount of water in the lake drops below 350,000 acre-feet, about the point where the layer of cold water above the old dam is exhausted.
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Power operations stop when lake dips to 400,000 acre feet
When the water level is around 400,000 acre-feet, power operations are suspended to make low level releases. This solution is effective until the layer of cold water above the old dam runs out. Suspending power operations reduces revenues from the project. The estimated loss from suspended power operations during the fall of 1994 was over $200,000.
New Melones is projected to drop below 350,000 acre feet sometime in May.
The Bureau has been making the drought situation worse since a decision last fall to release 23,000 acre feet of additional water for pulse flows to lure Chinook salmon up the Stanislaus River
That’s enough water to supply the domestic needs of the cities of Manteca, Ripon, and Escalon for more than three years or 331,000 Californians for a year,
And while it is being done in the name of helping the fish, biologist Andrea Fuller with Fishbio notes more than 10 years of intense studies show it will have a negligible impact if even that. And ultimately it could hurt fish.
“The planned higher flow only happens 1 percent of the time (naturally),” Fuller noted in September.
That means without New Melones and other reservoirs on the Stanislaus River the flow for October fish runs if left up to nature would only reach the level of 1,200 cubic feet per second only once every 100 years.
New Melones Reservoir had 606,918 acre feet as of midnight on Tuesday.
The SSJID has the ability to store 35,000 acre feet of water storage off stream that is shaping up to be critical for SSJID farmers and cities during the latter part of the irrigation season.
