Delta tunnel – commitment to updated science on sea level rise

On August 28, 2019, the Sacramento Press Club held a panel on Droughts, Tunnels & Clean Water: A Conversation on California Water Policy .  Panelists included  Secretary of Natural Resources Wade Crowfoot, MWD general manager Jeff Kightlinger, and the State water Contractors general manager Jennifer Pierre.

The transcript of the panel is now up on Maven’s Notebook.  Deirdre Des Jardins’ question is recorded:

I had a question about the Delta tunnel and sea level rise.  The last analysis that the North Delta intakes would stay fresh was done in 2010, which accounted for 55 inches of sea level rise and assumed no failure of the Delta levees.  My question for Mr. Kightlinger and Ms. Pierre is, are you going to do a new analysis for 10 feet of sea level rise?

The response by Jeff Kightlinger was explored in last week’s blog.   MWD is considering the cost-benefit tradeoffs of moving the Delta tunnel intakes north.

Secretary Crowfoot’s response is equally important:

I would add that’s the benefit of the new environmental review is to bring in updated scienceI think its scary for anybody who watches how these projections about sea level rise are changing, the acceleration of ice melt in the arctic so this new CEQA analysis will build in, as I understand, with the updated science as it relates to sea level rise.”

The Newsom administration’s expressed commitment to using updated science on sea level rise for the new CEQA analysis is long needed.  In 2014, a prescient review by the Delta Independent Science Board stated:

The potential direct effects of climate change and sea-level rise on the effectiveness of actions, including operations involving new water conveyance facilities, are not adequately considered. […] Similar comments could be made about the treatments of other disrupting factors, such as floods, levee failures, earthquakes, or invasive species, any of which could profoundly alter the desired outcomes of BDCP actions.

In their response to our preliminary draft review, the Department of Water Resources noted that “the scope of an EIR/EIS is to consider the effects of the project on the environment, and not the environment on the project”. If the effects of major environmental disruptions such as climate change, sea-level rise, levee breaches, floods, and the like are not considered, however, one must assume that the actions will have the stated outcomes. We believe this is dangerously unrealistic. 

(underlining added.)

In 2018, the Delta Stewardship Council’s Draft Staff Determination on WaterFix Consistency Appeal stated:

… the Department stated its assumptions still reflect the use of best available science because they are consistent with the recommended estimates for the sea-level rise under the “likely range” reported for years 2030 and 2060 in the latest guidance from the California Ocean Protection Council for sea-level rise planning.The California Ocean Protection Council, however, recommends the “likely range” for use in low risk aversion decisions, such as a coastal unpaved trail. (Ocean Protection Council, 2018 Update, p. 25.) Whereas, it recommends use of the H++ scenario, which is extreme risk aversion, for projects with a lifespan beyond 2050. (Ibid.)

The H++ scenario, from the 4th National Climate Change Assessment, projects up to 6.6 feet of sea level rise at the Golden Gate by 2080, and up to 10.2 feet of sea level rise at the Golden Gate by 2100.  These dates would be about 40-60 years after any Delta tunnel project was finished.

While the H++ scenario is a maximum estimate, it is important to use conservative design assumptions for sea level rise in the engineering design.  The rate of mass loss in the West Antarctic ice sheet has tripled in recent years.


One thought on “Delta tunnel – commitment to updated science on sea level rise

  1. Ms. Des Jardins continues to be the primary scientific mind focusing clearly on the challenges of the state’s proposal to consider building a mega-tunnel under the Sacramento-San Joaquin Delta. It is encouraging to see our California Resources Secretary starting to pick up on Des Jardins’s on-target warnings

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