Climate Change and the Delta: A Synthesis (Public Review Draft)

The Delta Reform Act of 2009 (Water Code Section 85066) requires that the Delta Stewardship Council adopt a Delta Plan (the Plan) to achieve the coequal goals of providing a more reliable water supply for California and protecting, restoring, and enhancing the Delta ecosystem (Water Code Section 85000). In the time since the Plan was adopted in 2013, a significant shift in State planning for Delta ecosystem protection, restoration, and enhancement has occurred, prompting review of the Delta Plan to  examine whether its strategies are still suited to achieve the ecological goals of the Delta Reform Act. As such, the Delta Stewardship Council (Council) is developing an amendment of the Plan’s Chapter 4, Protect, Restore, and Enhance the Delta Ecosystem.

Council staff are reviewing the best-available science to inform amendment of Chapter 4 of the Delta Plan. To support this effort, Council staff have developed three science  synthesis papers. This paper focuses on the effects of climate change in the Delta and is accompanied by two other papers focused on the Delta ecosystem (terrestrial and  aquatic resources) and restoration. Climate change is of interest for the Chapter 4  amendment given recent rapid advancements in research on climate change and its  effects on the Delta ecosystem that have occurred since the Delta Plan was adopted in  2013 (Dettinger et al. 2016).

Climate change has the potential to significantly affect the Delta ecosystem by raising  air and water temperatures, changing the timing and volume of flows into and through  the Delta, increasing tidal inundation with sea-level rise (SLR), and increasing salinity  intrusion into the Delta. Climate change is recognized as a global stressor in Chapter 4 of the 2013 Delta Plan, but the effects of climate change on Delta ecosystems are  discussed only briefly and with limited consideration of management strategies that address the issue. Chapter 4 of the Delta Plan identifies five key stressors to the Delta  ecosystem and core strategies for addressing each. Climate change has interrelated  effects on all five core strategy areas: Delta flows, habitat, water quality, non-native 28 species, and hatcheries and harvest management.

The Delta Reform Act specifies consideration of “the future impact of climate change and sea-level rise” (Water Code Section 85066), and identifies a restoration timeline horizon of 2100 (Water Code Section 85302). More generally, Executive Order B-30-15, signed by Governor Brown in April 2015, requires that State agencies incorporate climate change into planning and investment decisions, and that they prioritize natural infrastructure and actions for climate preparedness.