State of the Estuary 2019 Update

The San Francisco Estuary is a large and diverse system. Hundreds of miles of coastline stretch from the wide valleys of the Sacramento and San Joaquin Rivers to the steep headlands of the Golden Gate, with vast agricultural fields in the Delta and urbanized shorelines in Silicon Valley and many of the region’s cities. The complexity and scale of this system means it can take years to detect and assess changes.

This interim State of the Estuary Report checks in on a few indicators of health and explores where the assessment should head over time. In the four years since the 2015 State of the Estuary Report, two issues have emerged as critical to how we assess the health of the estuarine ecosystem at the heart of the Bay Area and the Delta. First, the health of the Estuary and of the people who live near it and depend on it are inextricably linked. We need a healthy Bay and Delta to protect our shorelines from sea level rise, help keep our waters clean, provide food and habitat for fish and wildlife, and give people a place to enjoy nature. We also need to think more about human communities as we assess the health of natural communities. This focus means addressing environmental injustices that are deeply embedded in our culture and patterns of development. The second critical issue to emerge is the need for a greater focus on landscape resilience—how well the Bay and the Delta are equipped to respond to change—so that people and wildlife can thrive as climate change progresses. Taking these two ideas together, this report focuses on the nexus of social and ecological resilience as we look toward the future.

The first section of the Report updates indicators of ecological health that span the entire extent of the San Francisco Estuary (Bay and Delta). Recent data show continued progress along the trajectories of the past decade. Tidal marsh restoration is proceeding at a brisk pace in the Bay and gaining traction in the Delta, while urban water conservation continues to meet mandated benchmarks, even during the drought. On the other hand, flows through the Estuary and across its floodplains continue to be well below levels that could increase and restore ecosystem health. Freshwater flows are a lynchpin of ecosystem processes that sustain physical habitats, fuel the food web, and regulate water quality. Creative approaches to using and re-using fresh water for environmental purposes are needed. Long-term trend analysis shows that fish communities in the Bay are declining. This analysis scores an index of 10 attributes of a healthy fish community.

The index focuses on fish in offshore areas, and may not capture benefits to fish from near-shore wetland restoration projects. Despite this slow decline, fish communities in the saltier parts of the Estuary remain in good condition, while those in the brackish and freshwater areas are in poor condition.

The next section of the report discusses three emerging indicators of Estuary health, offering options for how to assess resilience in future reports. Here, for the first time, the resilience of the Estuary’s shores is evaluated through the lens of subsidence and nature-based features. Elevation relative to sea level is a basic currency that must be tracked as the Pacific Ocean rises into the Estuary. The potential for the Estuary shore to be resilient to climate change and continue to provide benefits to people is related to how much of the shore zone is nature-based.

The final emerging indicator, urban green space, is a first attempt to assess how access to nature is distributed across more and less advantaged communities. More work is needed to finalize all these emerging indicators before they can be included in any future quantitative assessment of the State of the Estuary.

These emerging and updated indicators will help focus efforts to restore the Estuary’s health. In addition to continuing the successful aspects of restoration and conservation that this report describes, we need more investment in creative ways to use and restore flows for environmental health, to expand and build resilient shorelines and to weave considerations of social equity more strongly into efforts to improve environmental health.

– J. Letitia Grenier, Lead Scientist