The National Marine Fisheries Service (NMFS) is responsible under the Endangered Species Act for protecting the endangered Winter Run Chinook salmon of the Sacramento River. But when the US Bureau of Reclamation (USBR or Bureau) and the Department of Water Resources (DWR) have asked NMFS to comment on proposed changes in Central Valley Project operations during the present four-year drought, NMFS has consistently concurred, often going against its own previous prescriptions and advice. As a consequence, the Winter Run salmon were put at great risk, decimating the 2014 and 2015 year classes and again placing the population at the brink of extinction.

January 29, 2015 Letter on Old and Middle River Flows

On January 29, 2015, NMFS wrote a letter in response to the Bureau and DWR’s January Temporary Urgency Change Petition (TUCP) to the State Board.¹ The Petition asked the State Board to weaken State water quality standards. NMFS stated:

Here’s what we learned from monitoring salmon in 2014 that will inform our strategies for managing the drought in 2015:

1. Managing Old and Middle River (OMR) flow regimes to protect salmon is critically important. Effectively managing flow regimes allows juveniles to stay in the best habitat in the North Delta, ensuring they are not drawn toward the South Delta pumps where they are frequently killed by predators or the pumps themselves. During a rare rainstorm last March, and under a flexible operation approved as part of the 2014 Drought Contingency Plan, we allowed for higher levels of pumping and reverse OMR flows.  Evaluating the effects of the action this fall, we learned that salvage and loss of juvenile Chinook salmon, including winter-run, at the federal and state fish collection facilities increased when OMR’s 14-day running average was more negative than -5,000 cfs. This confirms the importance of managing OMR flows carefully to ensure pumping is increased when it will be most effective for increasing water supply and least impactful to juvenile fish.

Regardless of whatever NMFS had learned from events in 2014, NMFS had already ignored these lessons in December 2014 when it allowed OMRs to significantly exceed the -5000 cfs limit (Figure 1). NMFS then acquiesced to high reverse flows in the 2015 Drought Operations Plan: “OMR shall be no more negative than -5,000 cfs as a 14-day running average, and no more negative than -6,250 cfs as a 5-day running average, except as needed to capture sporadic storms (increase exports).”

The first winter storms usually trigger emigration of juvenile Winter Run and Late Fall Run Chinook salmon into and through the Delta (Figure 2). The only time during a drought that operators can achieve the highly negative OMR levels is in sporadic storms. Since those are precisely the conditions under which emigrating salmon pass through the Delta, the highly negative OMR flows put migrating juvenile salmon at great risk.

Figure 1. Old and Middle River flows in December 2014. Negative or reverse flows are caused by South Delta Exports, which reached over 10,000 during the second week of December 2014. (Data source: CDEC)

Figure 2. Occurrence of juvenile salmon in winter 2004 in seines and trawls near Sacramento at entrance to tidal Delta. Other years have shown a similar pattern. (Source: http://www.science.calwater.ca.gov/pdf/ewa/ support_docs_110804/Salmon%20Criteria%20Figures%201_2_Chappell.pdf )