Federal water purveyors scrambling to reduce the potential of flooding this winter are about to send water flowing through South San Joaquin Irrigation District canals that normally dry up in October.
The water will flow all the way through district canals and spill out into the San Joaquin River at French Camp and Little John Creek north of Manteca.
Water levels on the Stanislaus River will continue to run unseasonably high with flows increasing even more at times over the next 33 days.
It is all part of a plan to increase storage in New Melones Reservoir by Nov. 1 without killing spawning native fish on the Stanislaus River or imperiling levee work the state is currently performing southwest of Manteca.
New Melones - which holds 2,419 million acre feet of water - was at 2,065 acre feet as of Wednesday at midnight. The goal is to get New Melones down to 1.9 million acre feet by Nov. 1
Lowering the level of water in New Melones is critical to reduce the prospect of flooding southwest of Manteca along the Stanislaus and San Joaquin rivers as well as in the Delta. The water level was lower than 1.9 million acre feet in the early part of December 1996 when extremely heavy early winter snowpack fell. That was followed over Christmas by unseasonably warm and heavy rain in the higher elevation forcing a premature melting of the snowpack. The end result was flooding 70 square miles between Tracy and Manteca in January 1997.
There was $100 million in damage done in 1997 dollars, more than 3,000 people evacuated, 700 structures damaged, and Weston Ranch was placed on standby evacuation notice. At the same time Caltrans crews plugged undercrossings at McKinley Avenue on the 120 Bypass and Louise Avenue on Interstate 5 - with piles of dirt ready to put in place at Lathrop Road at I-5 - to convert the two freeways into back-up emergency levees if the need arose.
Water is now flowing into New Melones at 1,188 cubic feet a second while outflow is now at 3,582 acre feet. But once SSJID and Oakdale Irrigation District stop taking deliveries Friday, the amount of water flowing down the Stanislaus will increase raising water levels from Knights Ferry to Caswell State Park.
SSJID currently is taking 750 cubic feet per second. That diversion ends on Sept. 30.
Under the plan to lower New Melones levels as safely as possible, the SSJID will take 300 cubic feet per second from Oct. 1 to Oct. 25 and then kick it up to 800 cubic feet per second from Oct. 26 through Nov. 1
Meanwhile, the Bureau will continue the current level of water releases from New Melones and slowly taper it down to 1,000 cubic feet per second. Initially at least 450 cubic feet per second of water will flow down the river past points such as Ripon raising the water level even higher. Without the SSJID diversion the water level would even be higher than is now being projected.
The only thing that could go wrong with the plan is if there is heavy rain in the next 33 days.
The SSJID suggested the plan that the Bureau of Reclamation quickly accepted.
It is a move that will prove particularly beneficial to SSJID:
•It is allowing the district to extend irrigation to farmers that want it until Oct. 28.
•Water levels will remain higher throughout the winter at Woodward Reservoir that also benefits recreation use.
•The district will be able to take delivery of water after Sept. 30 without cutting into their allocation of 300,000 acre feet for the 2011-12 water year that starts Oct. 1. That, in turn, will provide SSJID with a large cushion of water at Woodward in the event of a drought next year.
•Two SSJID power generation plants will run through October resulting in more revenue from sales to Turlock irrigation District.
•SSJID is also benefiting from increased power generating revenue from the Tri-Dam Project it operates jointly with OID. Exact increased revenue to the district hasn’t been projected but in past years the SSJID has netted as much as $14 million as its share of Tri-Dam power proceeds.
The SSJID is the only viable option the Bureau has to take its excess water without dumping it all down the Stanislaus.