Sediment Solutions

Bay Area creeks have been heavily modified for flood control and development. Actions like channel extension, straightening, widening, and construction of levees have disconnected creeks from their surrounding floodplains and downstream baylands. Redesigning creeks to drain directly into tidal marshes provides a natural path for sediment delivery that will support long-term marsh resilience to rising sea levels.

This component of the project will advance planning in the North Bay (Lower Adobe Creek in Sonoma County) and East Bay (Lower Rheem Creek in Contra Costa County). SFEI will work with SFEP, The Watershed Project, and Friends of the Petaluma River to convene workshops with local communities, agency partners, regulatory agencies, restoration practitioners, and Tribal representatives to develop restoration concepts for the two creeks, and produce a Resilient Landscape Vision for each site. The Visions will reflect an alignment of restoration with community priorities, for example for flood management, marsh resilience, food web support, improved water quality, and other ecological, cultural, and recreational benefits. Both Visions will incorporate input from Tribal representatives, regarding the protection and enhancement of cultural resources. SFEI has conducted a similar collaborative visioning process in the South Bay and other areas in the past. 

Major goals of the visioning process are to advance equity in environmental decision-making by working directly with Tribal representatives and local communities to develop the Visions, and to improve the ecosystem services delivered to local communities from each creek and marsh.

Climate change will bring about changes to precipitation patterns that will drastically alter flood flows, erosion, and sediment delivery within Bay Area watersheds. The projected increase in large storm frequency will increase flood flows and watershed erosion, which could bring much-needed sediment to downstream marshes and mudflats. However, this change could also increase flood risk and the need to actively remove sediment from flood control channels, as well as have negative impacts on  habitat conditions for fish and invertebrates in stream channels and wildlife in adjacent riparian areas. By identifying actions to manage watershed peak flows and sediment dynamics, this component of the project seeks to support the sediment supply marshes and mudflats will need to keep pace with a rising sea level while supporting healthy stream ecosystems. 

This component of the project will focus on assessing sediment dynamics and developing management recommendations in a North Bay and South Bay watershed. SFEI is partnering with Sonoma Water and the Sonoma Resource Conservation District on an analysis of the Petaluma River watershed in the North Bay, and with Valley Water on an analysis of the San Tomas Aquino Creek watershed in the South Bay. In both watersheds, SFEI will assess current sediment sources, model current and future flow and sediment dynamics under different climate change scenarios, and identify current and future erosion/deposition hotspots. SFEI will then work with technical advisors and stakeholders to assess a suite of watershed management scenarios aimed at optimizing flow and sediment transport for supporting both marsh-mudflat and watershed ecosystems. Scenarios may include Green Stormwater Infrastructure implementation and restoration of floodplain and stream habitat. For both watersheds, scientists will evaluate how these actions support stream ecosystem health and benefit biodiversity throughout the watershed. The final synthesis reports for both watersheds will include projections of future sediment supply and dynamics, and recommended management actions to benefit watershed health, bayland health, and climate resilience. The findings will enable land managers in the study watersheds to take advantage of natural processes to achieve desired ecosystem benefits, today and in the future. The developed approach can then be applied in watersheds throughout the region.

Sediment Solutions aims to help inform future projects and provide lessons to other agencies around the region. The Coordination and Outreach component of the project focuses on disseminating the project outputs and advancing innovative tools and approaches that meet bayland sediment restoration needs and achieve long-term resilience. 

Communication and coordination with stakeholders will occur throughout the course of the project. SFEI will hold annual meetings to dialogue with stakeholders and to receive input on all project phases. Early meetings will focus on understanding stakeholder values and goals for the sites in question, as well as how to include stakeholder expertise throughout the project. Subsequent annual meetings will update this dialogue, provide the opportunity for two-way transfer of expertise, and allow for adjustments to the stakeholder process. SFEI staff also will give presentations at key conferences such as the State of the Estuary Conference and at local partner organization meetings. 

Regional Sediment Forums organized over the course of the project will bring together regulatory agency partners, water agency and municipal partners, restoration practitioners, construction representatives, NGOs, community organizations, and scientists. Discussion will focus on innovative approaches for meeting the future sediment need for Bay marshes and mudflats, and topics may include efforts such as regional coordination of upland excavated sediment, beneficial reuse, and peat farming to build elevation in marsh restoration projects.

Partnering with SFEP’s State of the Estuary Report, SFEI will also help develop a regional sediment indicator for baylands resilience. The indicator will show the current status of the sediment deficit across the Bay and include a trend score, helping the region track progress toward eliminating the current sediment deficit and achieving future resilient marshes and mudflats.