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High Stanislaus River flows

Intentional flooding part of fish survival research

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POSTED May 15, 2013 2:11 a.m.

Federal authorities are intentionally flooding low land along the Stanislaus River in a test to see whether it will help increase the chances of salmon fingerlings making it to the Delta.

It is a study that the South San Joaquin Irrigation District and Oakdale Irrigation District have been critical of as they contend the real problem on the Stanislaus River when it comes to salmon survival are non-native predatory stripped bass intentionally planted by the state starting in the early 1900s.

Currently, 96 percent of the salmon fingerlings at Knights Ferry do not make it to Vernalis south of Manteca where the Stanislaus River joins the San Joaquin River.

“With a 4 percent survival rate at that point, you can only imagine how many get through the Delta (to the Pacific Ocean),” noted SSJID General Manager Jeff Shields.

The Bureau of Reclamation and National Fisheries want to find out if increased flows above normal releases for a typical wet year will be enough to make the water murky and give the salmon fingerlings the chance to get pushed into backwater areas along the river where they’d have an improved chance to gain size - and the ability to elude predators - on their journey to the ocean.

Depending upon what the data shows and how the federal government draws its conclusions, the ultimate result of the study could imperil surface drinking water supplies for Manteca, Lathrop, Ripon and Tracy as well as irrigation water for the SSJID and OID.

That’s because the National Fisheries has pushed a management plan that calls for significantly increasing water releases from New Melones.  To do that, it would require tapping into the 300,000 acre feet of superior water rights that the SSJID and OID have on the watershed during dry years. Historical data indicates that in severe or critical stretches of drought it would require the virtual draining of New Melones to make the theory work.

A number of biologists are working along the river currently checking sensors placed as far as 300 feet from the normal river’s edge to measure seepage and track the fingerlings

The OID and SSJID commissioned an independent research focusing on keeping the non-native fish population that preys on the salmon fingerlings in check. Such a strategy would require less water diverted during the April-May salmon migration period.

High water is usually the norm this time of year on the Stanislaus River due to releases for the salmon migration.  It isn’t normal, however for a critical dry year that California finds itself facing for the second straight year. Instead it replicates a heavy spring run-off scenario.

Typically increased flows for the salmon migration on the Stanislaus are from April 1 to May 31. This year the Bureau compressed the flows into a period starting April 12 and ending May 21.

After May 21, water flows will start returning to normal.

The high flows in recent weeks have posed problems not just for landowners but also rafters and boaters who have been caught unprepared in the usually swift water.

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