Resilient landscape vision for Lower Walnut Creek

San Francisco Estuary Institute (SFEI) | November 30th, 2016

Lower Walnut Creek (Contra Costa County, CA) and its surrounding landscape have undergone considerable land reclamation and development since the mid-nineteenth century.

Lower Walnut Creek (Contra Costa County, CA) and its surrounding landscape have undergone considerable land reclamation and development since the mid-nineteenth century. In 1965, the lower 22 miles of Walnut Creek and the lower reaches of major tributaries were converted to flood control channels to protect the surrounding developed land. In the recent past, sediment was periodically removed from the lower Walnut Creek Flood Control Channel to provide flow capacity and necessary flood protection. Due to the wildlife impacts and costs associated with this practice, the Contra Costa County Flood Control and Water Conservation District (District) is now seeking a new channel management approach that works with natural processes and benefits people and wildlife in a cost-effective manner. Flood Control 2.0 project scientists and a Regional Science Advisory Team (RSAT) worked with the District to develop a long-term management Vision for lower Walnut Creek that could result in a multi-benefit landscape that restores lost habitat and is resilient under a changing climate. Development of the Vision began with technical analyses focused on understanding past and present landscape functioning and the changes to key processes and landscape features over the past 150 to 200 years. The key findings from these analyses include the following: • Landscape change – During the mid-19th century, lower Walnut Creek was surrounded by a continuous expanse of tidal wetlands occupying approximately 5,000 acres. Perennial freshwater marsh, willow thicket, and alkali meadow formed a large non-tidal wetland complex that adjoined the tidal marsh on its southern end. Over the past century and a half, the non-tidal wetland complex has been lost completely and the tidal wetland area has decreased by 40%. The remaining marsh areas are highly fragmented and cut-off from Walnut Creek by engineered levees. The loss of tidal wetland area has resulted in a substantial decrease in tidal prism and contributed to current in-channel sediment accumulation issues. Around the mouth of Walnut Creek, sediment accumulation has caused the position of the shoreline to expand into the Bay by up to half a mile. • Sediment accumulation – Since 1965, approximately 1.4M cubic yards of sediment have been removed from lower Walnut Creek, with approximately 70% coming from the tidal zone downstream of head of tide (i.e., the inland extent of tidal inundation at mean higher high water). Repeat channel cross-section surveys indicate that the channel quickly fills in with sediment following dredging events (due in large part to decreased tidal prism and associated channel scour capacity) and that the channel bed elevation is currently at or near “quasi-equilibrium.” A channel sediment budget for 1965-2007 indicates that approximately 80% of the watershed-derived sediment made it through lower Walnut Creek and out to the Bay, while the remaining 20% was likely deposited directly following channel construction and subsequent dredging events.

Resilient Landscape Vision for Lower Walnut Creek: Baseline Information and Management Strategies

San Francisco Estuary Institute (SFEI) | November 1st, 2016

Lower Walnut Creek (Contra Costa County, CA) and its surrounding landscape have undergone considerable land reclamation and development since the mid-nineteenth century.

Lower Walnut Creek (Contra Costa County, CA) and its surrounding landscape have undergone considerable land reclamation and development since the mid-nineteenth century. In 1965, the lower 22 miles of Walnut Creek and the lower reaches of major tributaries were converted to flood control channels to protect the surrounding developed land. In the recent past, sediment was periodically removed from the lower Walnut Creek Flood Control Channel to provide flow capacity and necessary flood protection. Due to the wildlife impacts and costs associated with this practice, the Contra Costa County Flood Control and Water Conservation District (District) is now seeking a new channel management approach that works with natural processes and benefits people and wildlife in a cost-effective manner. Flood Control 2.0 project scientists and a Regional Science Advisory Team (RSAT) worked with the District to develop a long-term management Vision for lower Walnut Creek that could result in a multi-benefit landscape that restores lost habitat and is resilient under a changing climate. 

Resilient Landscape Vision for the Calabazas Creek, San Tomas Aquino Creek, and Pond A8 Area: Bayland-Creek Reconnection Opportunities

San Francisco Estuary Institute (SFEI) | May 1st, 2018

This report proposes a multi-faceted redesign of the South San Francisco Bay shoreline at the interface with Calabazas and San Tomas Aquino creeks. Recognizing the opport

This report proposes a multi-faceted redesign of the South San Francisco Bay shoreline at the interface with Calabazas and San Tomas Aquino creeks. Recognizing the opportunities presented by changing land use and new challenges, such as accelerated sea-level rise, we explore in this report a reconfigured shoreline that could improve ecosystem health and resilience, reduce maintenance costs, and protect surrounding infrastructure. 

Resilient Landscape Vision for Upper Penitencia Creek

San Francisco Estuary Institute (SFEI) | January 1st, 2019

This report proposes a new multi-benefit approach to flood management along Upper Penitencia Creek. Recognizing the creek’s complex history, land use, and challenges, t

This report proposes a new multi-benefit approach to flood management along Upper Penitencia Creek. Recognizing the creek’s complex history, land use, and challenges, this report explores a suite of actions that could help meet flood management objectives while improving ecosystem functioning, expanding recreational opportunities, and supporting water supply needs. 

Restoration of Hetch Hetchy Valley and San Francisco’s Water Supply

Restore Hetch Hetchy | February 10th, 2016

Q: After restoration, where will San Francisco gets is water? A: From the Tuolumne River, just as it does now. This report addresses only the most commonly asked ques

Q: After restoration, where will San Francisco gets is water? A: From the Tuolumne River, just as it does now. This report addresses only the most commonly asked question by restoration skeptics: Where would the water come from? Restoration would also require increased water treatment costs and replacement of about 350 gigawatt-hours per year of hydropower production – issues not addressed herein.

Restoration Vision for the Laguna de Santa Rosa

San Francisco Estuary Institute (SFEI) | April 1st, 2020

The Laguna de Santa Rosa, located in the Russian River watershed in Sonoma County, CA, is an expansive freshwater wetland complex that hosts a rich diversity of plant a

The Laguna de Santa Rosa, located in the Russian River watershed in Sonoma County, CA, is an expansive freshwater wetland complex that hosts a rich diversity of plant and wildlife species, many of which are federally or state listed as threatened, endangered, or species of special concern. The Laguna is also home to a thriving agricultural community that depends on the land for its livelihood. Since the mid-19th century, development within the Laguna and its surrounding watershed have had a considerable impact on the landscape, affecting both wildlife and people. Compared to predevelopment conditions, the Laguna currently experiences increased stormwater runoff and flooding, increased delivery and accumulation of fine sediment and nutrients, spread of problematic invasive species, and decreased habitat for native fish and wildlife species. Predicted changes in future precipitation patterns and summertime air temperatures, combined with expanding development pressure, could exacerbate these problems. People who manage land and regulate land management decisions in and around the Laguna, including landowners; federal, state, and local agencies; and local stakeholders, are seeking a long-term management approach for the Laguna that improves conditions for the wildlife and people that call the Laguna home. The California Department of Fish and Wildlife and Sonoma Water funded the Laguna-Mark West Creek Watershed Master Restoration Planning Project to develop such a management approach, focusing on the need to identify restoration and management actions that enhance desired ecological functions of the Laguna, while also supporting the area’s agriculture and its local residents.

Restoring Habitat with Science and Society in Mind

Delta Stewardship Council (Delta Council) | April 8th, 2014

This Issue Paper, authored by Jessica Davenport, the Council's Program Manager for Ecosystem Restoration and Land Use, is entitled Restoring Habitat with Science and Soci

This Issue Paper, authored by Jessica Davenport, the Council's Program Manager for Ecosystem Restoration and Land Use, is entitled Restoring Habitat with Science and Society in Mind.  The purpose of the 22-page paper is to survey restoration activities in the Delta; describe the needs, progress and opportunities related to restoration; and propose key areas of focus for the Delta Stewardship Council and other agencies to advance habitat restoration. Some of the areas of focus for Council staff for the next two years include: Continue to provide early consultation on habitat restoration projects that are Covered Actions under the Delta Plan in order to advise project proponents on using best available science and adaptive management and avoiding or reducing conflicts with existing uses, where feasible. Report on habitat performance measures by December 2014 and again in December 2015. Work with others to complete at least one of the landscape-scale conceptual models and associated landscape habitat metrics for the priority habitat restoration areas. Enagage Delta Plan Interagency Implementation Committee members in discussions of challenges and potential solutions related to land acquistion and permit coordination.

Restoring the Heart of a Healthy Estuary: A Review of Restoration in the Sacramento–San Joaquin Delta and Suisun Marsh

Publisher not available | December 19th, 2025

The restoration of native species-dominated ecosystems is critical for improving ecosystem health and meeting policy goals in the Sacramento–San Joaquin Delta and Suisu

The restoration of native species-dominated ecosystems is critical for improving ecosystem health and meeting policy goals in the Sacramento–San Joaquin Delta and Suisun Marsh (upper San Francisco Estuary, collectively), one of the largest estuarine systems in North America. To accomplish large-scale restoration in this heavily altered system, a variety of projects, programs, and motivations inform restoration planning and implementation. Chapter 4 of the Delta Plan synthesizes restoration goals across these efforts to produce comprehensive ecosystem restoration targets of between 60,000 and 80,000 acres across seven ecosystem types by 2050, but a comprehensive review of restoration progress and planning to date is needed. To fill this gap, this paper analyzes the current state of ecosystem restoration in the upper San Francisco Estuary in the context of the Delta Plan targets. We review current scientific and management literature and implementation approaches, and synthesize acreage totals across completed, in-progress, and planned projects for four ecosystem types where substantial development of restoration in the system has occurred: tidal wetland, non-tidal wetland, riparian, and floodplain. We find that tidal wetland restoration has progressed more rapidly than other ecosystem types, motivated by mitigation requirements related to the federal Endangered Species Act. Across all ecosystem types, we identify both promising progress and clear needs for accelerated planning and implementation of restoration projects to meet Delta Plan 2050 targets, and discuss ongoing needs related to science, funding, and implementation.

Rethinking Management of the Colorado River through Lake Powell, Grand Canyon, and Lake Mead

Utah State University | November 15th, 2024

Reversal in estuarine sand supply driven by Holocene sea level rise: A model for sand transport in large structural estuaries, San Francisco Bay, California, USA

Elsevier | July 26th, 2024

Coastal sand supply is a critical component of shoreline stability in the face of modern threats to coastal zones such as sea level rise or anthropogenic sediment extract

Coastal sand supply is a critical component of shoreline stability in the face of modern threats to coastal zones such as sea level rise or anthropogenic sediment extraction. Understanding the natural and anthropogenically perturbed dynamics of coastal systems has become a pressing challenge for coastal communities, such as the San Francisco Bay area in the United Sates, a large structurally controlled estuary system where stakeholders seek to balance the extraction of coastal sand resources for economic use and ensure sufficient sand supply for sustaining natural coastal environments. Developing accurate and comprehensive models of sand inputs and transport pathways in different types of coastal systems is imperative to balancing these competing needs. While estuarine sediment transport has been well-studied in many systems globally, structurally controlled estuaries in tectonically active settings have received relatively less attention. The prevailing hypothesis for sediment transport through San Francisco Bay describes active input and transport of sand from a large integrated regional catchment, through multiple subembayments, and out to Pacific coast beaches; a model contrary to prevailing understanding of highstand estuarine sediment transport in most settings. We test this model by applying comprehensive sand provenance analysis to surface and near-surface sand deposits in and around San Francisco Bay coupled with sand residence time data from optically stimulated luminescence (OSL) dating. New provenance results include sand petrography modal abundances, bulk geochemistry, and U-Pb detrital zircon geochronology from 27 Holocene samples throughout the San Francisco Bay region. Collectively, these new results highlight marked sediment provenance and residence time differences between San Francisco Bay structural subembayments. In particular, distinct compositional differences and OSL ages exist between sand in the bayhead region of the estuary (OSL ages ca. 4 ka; Sacramento River/local provenance) and sand from the more distal bay regions and the Pacific coast (OSL ages ca. 1 ka; integrated Sierra Nevada provenance). These provenance differences better support a revised sand input and transport model with disconnected depocenters across three structurally restricted subembayments from bayhead to the Pacific coast. New data suggest that at present the bayhead region receives limited supply from the Sacramento-San Joaquin Delta drainage with subsidiary supply from local circum-bay drainages. Sand deposited in the region from the Pacific coast through the inlet (Golden Gate) and into the estuary consists of a combination of tidal winnowing and reworking of “relic” sand from lowstand periods combined with sand eroded from Pacific coast sea cliffs, and sand supply from local Coast Range drainages. These results suggest that sand is likely not transported directly to the Pacific coast from the Sacramento-San Joaquin Delta under modern conditions. Moreover, it is likely that structural constrictions between the main estuary and outer coast and between estuary subembayments cause abrupt cessation of sediment input from the main regional drainage during marine flooding, a feature likely common to large structurally controlled estuaries globally. This revised model for San Francisco Bay sand transport illustrates the need for research targeted at interpreting natural sand transport pathways in coastal systems where coarse sediment supply is a sustainability concern.