DISB Review of the Final EIR/EIS for California WaterFix

The Delta Reform Act of 2009 directs the Delta Independent Science Board to review environmental impact assessments of the Bay Delta Conservation Plan (now California WaterFix). Here, in our fifth such review, we focus on the adequacy of the scientific information presented in the final Environmental Impact Report (EIR)/Environmental Impact Statement (EIS) for the California WaterFix by revisiting the six main concerns we raised in our September 2015 review of the Recirculated Draft EIR/Supplemental EIS. We discuss improvements and shortcomings. We also comment on the need to improve impact assessments for scientific evaluation and effective stakeholder engagement.

The Final EIR/EIS contains a wealth of detail and considerable insight. This version improves on its predecessors but retains some persistent shortcomings. Improved content on adaptive management is still short on detail about how adaptive management would be implemented under changing and uncertain conditions. Summaries and comparisons, more abundant than before, lack insightful syntheses and graphics that ease comprehension of the vast amount of material presented. Expanded discussion of Delta levees stops short of evaluating interactions with water supply reliability and neglects changing views of earthquake hazards. Long-term effects are better addressed in several ways, but with insufficient attention to uncertainties in defining the No Action Alternative and to the interplay between California groundwater sustainability and Delta water supplies. Other content missing includes evaluation of environmental effects of water use south of the Delta. Evaluation of ecosystem impacts, though extensive, retains gaps on using restoration as mitigation.

The completion of our reviews of the Final EIR/EIS and its predecessors prompt us to reflect more broadly on the use and communication of science in the Delta and more specifically on the false trade off between thoroughness and intelligibility that has become common in environmental impact assessments. Overwhelming readers with content that addresses the many scientific issues related to a proposed project and its alternatives, while neglecting the thoughtful presentation and synthesis of insights and performance trade offs among alternatives, diminishes the value of this important document as a comparative guide to the expected environmental effects of the alternatives considered.