DWR Chief Engineer warned of climate change draining northern California reservoirs

Governor Newsom’s drought emergency declaration is a direct consequence of the draining of Shasta, Folsom, and Oroville reservoirs by the Central Valley Project and State Water Project to export water from the Delta. Emergency operation of these major reservoirs will be a disaster for the Delta ecosystem, and will also have severe impacts on Delta water quality, migratory waterfowl, and Sacramento Valley and Delta agriculture.

People say, “at the start of every disaster movie there is a scientist being ignored.” For the past 15 years, modelers studying climate change impacts on the CVP and SWP have repeatedly warned of the need to modify reservoir operations to deal with climate change.

One major early study was associated with the Bay Delta Conservation Plan / WaterFix project. In 2009 and 2010, Francis Chung, DWR’s Chief of Bay Delta Modelling, oversaw studies of Central Valley Project and State Water Project operations with climate change, with and without the twin tunnels. Chung presented the results at the 2010 California Water and Environmental Modelling Forum at Asilomar. The modeling showed that climate change would cause a major increase in months with dead storage in north of Delta reservoirs, and even more with the twin tunnels project, new north of Delta storage and increased South of Delta groundwater banking.

Number of months of dead storage in repeat of 1922-2003 hydrology


D1641 — Bay-Delta Water Quality Control Plan regulatory requirements

(+) Wanger with CC —  2008 Obama biological opinion with climate change

(+) BDCP with CC — Twin tunnels with climate change

(+) NODOS with CC —  North of Delta offstream storage with climate change

(+) SOD GW Bank with CC — South of Delta groundwater bank with climate change


Chung concluded, “Results appear to be unsustainable. The relative frequency of dead storage conditions in upstream reservoirs indicate that significantly modified operations will be required with climate changed conditions.” Chung made the following recommendations:

DWR never has developed a reoperation strategy to mitigate the effects of climate change on north of Delta reservoirs. As a result, the draining of Shasta, Folsom, and Oroville reservoirs was a major issue in the State Water Resources Control Board’s hearing on the twin tunnels project. There was extensive testimony by experts on the need to develop better drought operations.

The WaterFix hearing ended, and the Water Board never formally considered the expert testimony. The disastrous consequences of ignoring the recommendations of Chung and other engineers studying the impacts of climate change on the CVP and SWP are now becoming clear.


Francis Chung, PhD, P.E. An Assessment of CVP-SWP System Performance Under Alternative Delta Regulations, Infrastructure and Climate Change Scenarios Using CalSim II, California Water and Environmental Modeling Forum, Feb. 22, 2010.

California Water Research, Delta Plan Comments: Water Supply Reliability, 2012.

Post updated to add Chung’s results.

5 thoughts on “DWR Chief Engineer warned of climate change draining northern California reservoirs

  1. Listen up and heed the warnings Gov. Newsom and as yet unnamed new US Commissioner of Reclamation: you are headed down the road toward dead storage in your reservoirs and need a reoperation strategy!

    1. I wondered the same thing:

      What is meant by dead storage in reservoir?
      Dead or inactive storage refers to water in a reservoir that cannot be drained by gravity through a dam’s outlet works, spillway, or power plant intake and can only be pumped out. Dead storage allows sediments to settle, which improves water quality and also creates an area for fish during low levels.

      Reservoir – Wikipedia

      1. Thank you Tim. When a reservoir is at dead storage, water levels are so low that no water can be released from the reservoir. In the huge Sierra rim reservoirs, dead storage is a catastrophe for all beneficial uses in the watershed.

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