1. “Its All About the Sediment”
San Francisco Bay
“Its All About the Sediment”
Brenda Goeden
San Francisco Bay Conservation and Development Commission

2. Approximately 54 Square Miles Today
San Francisco Bay
Approximately 54 Square Miles Today
Two Major Fresh Water Rivers to the East:
Sacramento and San Joaquin
Drain 40% of the state
The San Francisco Bay proper, covers 54 square miles, almost a third smaller than it was before development of the region. It has two very large rivers which drain 40 percent of the landmass of the state of California through the Delta. It is an estuary made up of a primarily mud bottom, but has high energy areas that are sandy as a result. BCDC’s jurisdiction includes the Bay itself, certain named waterways, the adjacent marshes and 100 feet landward of mean sea level. This is an important consideration when examining the possibility of a sediment management program for the region. We are a bit in the middle space between the rivers that bring the sediment into the system and the outer coast.

3. 1849
2100 3

4. The New World: Sea Level Rise
Changed Situation
The New World: Sea Level Rise
Area subject to high tide with 16 inches of sea level rise
The 100 year storm: Areas at risk to 1/100 chance of flooding per year,
In 50 years the Bay’s 100 year storm will be high tide
Current 100-year flood plain

5. Floods
Storm Surge

6. Shoreline and Beach Erosion

7. The New World: Sediment Deficit
Changed Situation
The New World: Sediment Deficit
Point San Pablo, mid-depth, Dave Schoellhamer, USGS

8. Why Do We Care?
Shorelines
Levees
Habitat
Sea Level Rise

9. What’s Changed?
The System? Our Understanding of the System? Sediment Rich Sediment Poor

10. 1990/2011 San Francisco Bay Historic marshes diked off
Historic beaches no longer connected
Watersheds channelized
Watersheds clogged with fine grain sediment
Sediment trapped behind dams
Shoreline developed
Water from Delta controlled

11. Sediment Supply Shift: from the Delta to local tributaries
Changed Situation
Sediment Supply Shift: from the Delta to local tributaries
Where we used to see the Delta as our main source of sediment, we now will need to look to our local watersheds to supply the sediments to sustain our shorelines, beaches and marshes.
Oakland Museum Creek Guide

12. A Large Water and Sediment-shed

13. Local Tributaries are Becoming Increasingly Important
Clemson University

14. Embayments: Erosional & Depositional
San Pablo Bay - Erosional
Central Bay - Erosional
South Bay - Depositional
Fregoso, Jaffe, Foxgrover, USGS

15. Ebb-Tide Delta Erosion
Sediment Removal from system
Changed wave refraction
Erosion along outer coast
Dallas & Barnard, USGS

16. Sand mining removing sand
Sand appears slow to replenish
Patrick Barnard & Rikk Kvitek

17. Dredging Projects Federal Channels Ports Refineries Marinas
The biggest area in which we can manage sediment is in dredging projects. We have approximately 90 dredging projects in the Bay, including federal navigation channels, ports, refineries and marinas. This represents between 3 and 4 mcy of sediment dredged each year, down from a high of 6 mcy.

18. Ocean Disposal Site In-Bay Disposal Sites Alcatraz San Pablo Bay
Carquinez Strait
Suisun Channel
Historically dredged material had been disposed at various sites around the Bay. Changes to agency dredging programs lead to the designation of four in Bay disposal sites and one site adjacent to the main ship channel entering the Bay.
Ocean Disposal Site

19. Dispersive In Bay sites
Carquinez
San Pablo
Alcatraz
LTMS EIS/EIR

20. Ocean Disposal Removes Sediment from the System

21. FINAL EIS/EIR
LTMS MANAGEMENT STRATEGY FOR THE PLACEMENT OF DREDGED SEDIMENT IN THE BAY AREA
Percent of all Disposal
Through a number of studies and completion of and EIS/EIR, the LTMS strategy focused on reusing as much dredged sediment as possible, targeting a maximum of 20% of in Bay disposal, a minimum of 40% beneficial reuse and the remaining 40% or less disposed of at the deep ocean disposal site.

22. HAMILTON WETLANDS WITH BEL MARIN KEYS PARCEL V ADDITION
MONTEZUMA
WETLANDS
HAMILTON WETLANDS WITH BEL MARIN KEYS PARCEL V ADDITION
Two additional restoration projects – a private project in Collinsville is the Montezuma project. The second is the Hamilton Wetlands project in Novato, with the addition of Bel Marin Keys V as part of WRDA 2007, brought the project to 2100 acres and a needed 24 mcy of dredged sediment. The Hamilton project is a federal/state/industry partnership with 3 mcy of sediment coming from the Port of Oakland 50 foot deepening project, the Coastal Conservancy being the State Partner and the Corps being the federal partner.

23. SONOMA BAYLANDS
Our first major effort was the Sonoma Baylands: ~2.5 million cy of clean dredged material from the Port of Oakland -42-foot deepening project was used to create 322 acres of tidal and seasonal marsh and endangered species habitat. Dikes were breached and tidal action reintroduced in years later, it is transitioning nicely into a restored and healthy marsh. Without dredged sediment placement, it is likely that this site would take 50 years to a restored state.

24. In An Ever Changing World “New” Issues to Contend With…
Watershed Management
Shoreline
Protection
Climate
Change
Habitat Restoration and Maintenance
Sediment Supply and Demand
Dredging and Aggregate Mining

25. Regional Sediment Management Is…
The integrated management of littoral, estuarine, and riverine sediments to achieve balanced and sustainable solutions to sediment related needs.” Regional sediment management recognizes sediment as a resource. Sediment processes are important components of coastal and riverine systems that are integral to environmental and economic vitality.

26. Shorelines, Marshes and Beaches need sediment to keep up with sea level rise
Prbo study with PWA
PWA & PRBO in review

27. Flood Protection is a Key Component in Regional Sediment Management
Walnut Creek
Need to Find New Ways to Protect From Flooding and Support Sediment
Supply to Wetlands and the Bay
Ballona Creek

28. To Respond to a Changing Bay, A New Approach and Much Coordination is Needed

29. Management Considerations and Planning
Scientific Inputs
Management Considerations and Planning
of Programs Affecting Sediment Supply and Demand
Optimized Management

30. New Areas to Consider Sediment Sources and Sinks
Flood Protection
Aggregate Mining
Dredging
Wetland Restoration
Beach Nourishment
Shoreline Protection

31. Local Tributaries Sediment
Flow Analysis
Quantify local tributaries contribution to Bay sediment budget
Corte Madera & Alameda Creeks
Sediment gauges at head of tide and creek mouth
Sediment flow and flux between creek and Bay
Short term study – need funding to continue
First step in developing a predictive numerical model for local tributaries
Working with SFEI and USGS

32. Corte Madera Creek Study
Wetland wave attenuation study
Resilience of tidal marsh to sea level rise and coastal flooding
Improve analytical tools for assessing flood risk
Improve guidance for local decision makers
Use data to build and calibrate 2D and 3D models
Collect and analyze sediment cores for sedimentation rates and peat accumulation
Working with USGS and Marin County Flood Control & Water Conservation District

33. Modeling Can Help
Tidal Hydrology
Watersheds
Sediment Transport

34. Flood Districts and Watersheds
Need
Flood Districts and Watersheds