Soft Shores

Measures the type and distribution of land cover along the shoreline, with undeveloped land ranked as softest

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Tidal Marsh softens the shoreline. Shirea Bezalel, SFEI.

Tidal Marsh softens the shoreline. Shirea Bezalel, SFEI.

Softer Shorelines Buffer Floods While Offering Space for Wildlife and Recreation

Soft shores provide flood resilience and various co-benefits, including wildlife habitat, natural carbon management, and water quality improvements. Features like marshes and undeveloped land can absorb floodwater and adapt to rising seas, unlike sea walls and levees, which can fail suddenly and irreparably.

tidal marsh fronting an oil refinery
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Fronting an oil refinery on North Richmond’s shoreline, a tidal marsh provides a vital natural barrier against sea-level rise and storm surges. Ben Botkin, San Francisco Estuary Partnership.

Soft Shores

Status & Trend

Latest Update: October 2025

Bay and Delta statuses are Fair, trend data not available until future updates
Soft Shores scored Fair in the Bay and Delta (including Suisun Bay), with variation between sub-regions. 2025 was the baseline year for Soft Shores, and trends will become apparent in future years. North Bay scored Fair because it has moderate amounts of open space and marshes. Conversely, Central Bay scored Poor because urbanization has left little space for marshes—though those that persist are valuable for people. Managed ponds and marshes dominated Suisun and South Bay, warranting Good scores. In the Delta, once-sprawling marshes have been diked and converted to farmland. The Fair score reflects how agriculture can more readily recover from floods compared to dense development.

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Soft Shores in Depth

The Bay and Delta shoreline is threatened by flooding from storms and high tides. This risk is expected to increase over the coming decades. Infrastructure such as levees and seawalls that “harden” the shoreline provide flood protection, but often have high maintenance costs and are vulnerable to catastrophic failure.

Natural infrastructure, such as marshes, mudflats, beaches, and some terrestrial habitats, also offers flood protection and can adapt and recover without human intervention. These Soft Shore elements are more dynamic than static gray infrastructure because they move with and recover from floods (Hill 2015). Natural infrastructure also provides other benefits, including habitat, natural carbon management, and stormwater pollution treatment. Natural infrastructure can be used alone or to shore up at-risk levees, berms, and flood walls. See SFEI and SPUR (2019) for more examples of how hard and soft shoreline features can be used together.

Soft Shores provides a regional snapshot of dynamic natural infrastructure by quantifying the amount of resilient habitats and land use types that surround the shore. Given the potential of soft shores to offer critical co-benefits for people and wildlife, we track these interventions separately from hardened infrastructure. The Bay Conservation and Development Commission’s Shoreline Vulnerability Index provides a complementary measure of shoreline vulnerability that accounts for protection from soft and hard shorelines.

Many efforts around the Bay encourage the use of soft shore features to alleviate impacts of sea level rise and storm surge. These include but are not limited to The San Francisco Estuary Blueprint, Bay Adapt Joint Platform, and several projects funded through the Delta Conservancy’s Nature-Based Solutions: Wetland Restoration Funding (Delta Conservancy 2025).

Aerial view of marsh and farmland by a river
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Aerial view of the patchwork patterns of agricultural fields next to marsh restoration where the San Francisco Bay meets the Sacramento-San Jaoquin Delta.

Aerial view of the patchwork patterns of agricultural fields next to marsh restoration where the San Francisco Bay meets the Sacramento-San Jaoquin Delta.

How was this Indicator Calculated?

Data Used

We used land cover & habitat mapping from the Delta Aquatic Resources Inventory (SFEI 2022), Baylands Habitat Map 2020 (SFEI 2024), DWR Statewide Crop Mapping (CDWR 2020), and National Landcover Dataset 2020 (USGS 2021).

Indicator Approach

We used land cover/land use data to assess the distribution of soft shorelines within 200m buffers on either side of the shoreline (400m total width). We first defined the shoreline as the boundary between intertidal and non-tidal areas using a combination of land use, land cover, and habitat mapping. We then summarized land cover/land use into seven categories along a gradient of “softness”, ranging from the “hardest” urbanized areas to the “softest” vegetated intertidal habitats and undeveloped land. We broke up the set-distance buffers into sampling units roughly 250m in width parallel to the shoreline and assigned a rating to each based on the hardness and softness of its dominant land covers/land use category. Based on these ratings for individual sampling units, we derived a Soft Shoreline Index of 0-10, with 10 being the “softest” and 0 being the “hardest” conditions, which we applied to five regions of the Estuary (Delta, Suisun Bay, San Pablo Bay, Central Bay, and South Bay), and to rolled up scores for the Bay and Delta (including Suisuin Bay).

Benchmarks and Scoring

The 2025 indicator’s 2020 map-year serves as the baseline condition for future indicator updates. We set benchmarks so that changes in status scores are sensitive to how much we expect conditions could feasibly deviate from this baseline. If planned and plausible restoration and nature-based projects take place, scores will improve toward the “best-possible” maximum score of 10. We expect regional scores of 10—where shorelines would have completely undeveloped backshores and tidally vegetated frontage—to be unlikely in the highly urbanized regions of the Estuary. Thus, the benchmark for a Good status score is 5 and above, representing about 50% progress toward the “best-possible” scenario. If shorelines continue to be developed, and hardened flood protection is implemented without any accompanying nature-based approach, scores will decline toward 0. The benchmark for a Poor status score is below 2.5. Future Bay, Delta, and sub-regional trend scores will reflect the change in the Soft Shore Index in those regions relative to their baseline values.

Technical Appendix

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Related Indicators

Resilient Processes Category

Beneficial Floods

Measures the extent to which freshwater flows create seasonal floodplain habitat upstream of the Delta and low-salinity habitat in the Bay

Migration Space

Measures the amount of protected and undeveloped uplands where tidal habitats can shift inland as sea levels rise (Under development)

Sediment

Tracks sediment supply to existing and restored baylands from natural and engineered sources within San Francisco Bay (Under development)

Subsided Lands

Tracks land area in the Estuary that has sunk below historical elevation levels and land management practices that reverse or halt the subsidence process

Tidal marsh and water

Tidal marsh in Petaluma, CA. Mark Jones, MTC.

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Tidal marsh in Petaluma, CA. Mark Jones, MTC.

Contributing Scientists | Soft Shores

Cate Jaffe, San Francisco Estuary Institute
Katie McKnight, San Francisco Estuary Institute

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