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More science they didn’t want to hear

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On Day 2 of the DSC meeting, Dr. Richard Norgaard, chair of the Delta Independent Science Board, reported to the DSC about the ISB’s work on stressors.  Norgaard told the council that there is no scientifically objective, agreed upon method for ranking stressors.  Said Norgaard, “We’re giving you a report on addressing multiple stressors to explain that we can’t rank them, and why.”  He did his best to make it clear that the ISB hadn’t promised to deliver any ranking of stressors later.

The report does list drivers and stressors but does not rank them.  “Drivers” are sources or creators of stress that exert pressure on the ecosystem.  For example, climate change is a driver, whereas sea level rise is a stressor.

The U.S. Geological Survey (USGS) made two presentations, one on seismic risk in the Delta and the other on ground water and subsidence.

The PowerPoint on seismic risk provided support for the argument that we’re due for a Big One, showed all the different faults in or near the Delta, and included an impressive animation sequence.  But in public comments, Tom Zuckerman of the Central Delta Water Agency raised some important points that the USGS had omitted.

Regarding threats of Delta levee collapse, Zuckerman noted that the earthquake in Kobe, Japan in 1995 that killed thousands of people and caused the failure of buildings and other infrastructure did little damage to levees.  Pictures of levees following the Kobe earthquake show surface collapse, but the levees themselves did not fail.  That is because liquefiable material under levees was confined.  He questioned the assumption by USGS in its Delta Risk Management Study that all the material under Delta levees is unconfined and said that if you look at the actual structure of Delta levees, you will get different results than DRMS got.

Gil Cosio of MBK Engineers, which does work for 27 reclamation districts, confirmed that movement of levees doesn’t cause them to fail.  Proper foundation compression and staging of levee construction can maximize the ability of levees to withstand seismic activity.

Any earthquake that affects the Delta will also have major impacts elsewhere.  Zuckerman mentioned the 300-400 miles of vulnerable facilities outside the Delta, including the California Aqueduct and the Delta Mendota Canal that parallel blind thrust faults along the coast range.  (Blind thrust faults do not rupture all the way up to the surface.)

A presentation by USGS on Ground Water and Land Subsidence revealed additional threats to transfer infrastructure.  Land subsidence in the Delta affects the top layers of land surface, but subsidence due to groundwater pumping in the San Joaquin Valley causes the aquifer system itself to compact.  The California Aqueduct and the Delta Mendota Canal lie along the area of greatest subsidence.  Canal liners and pumping facilities have had to be raised and gates built up; transfers capacity has been lost.

San Joaquin Valley export users argue that they wouldn’t have to pump as much groundwater if they got more surface water.  The trouble is, the surface water has to come from somewhere.  As part of its mandate, the DSC will have to consider the effect of surface water diversions on Sacramento Valley aquifers, the largest of which (the Lower Tuscan) is partly a fractured rock aquifer that cannot be recharged.

As Chair Isenberg said, “Who uses less so someone else can get more?”

In our last newsletter, we reported that the State Water Project faces delivery problems, deferred maintenance, and even fines resulting from its inability to retain qualified dispatchers and other system operators.  Clearly, California’s water transfer infrastructure and water reliability are also threatened by potential earthquakes and ground subsidence.  And that’s OUTSIDE the Delta.

With so much that we can’t foresee or predict, why would Californians want to bet their water future on more large-scale, highly engineered infrastructure rather than on smaller, more adaptable regional projects?

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