1. Bay Sediment Budgets: Sediment Accounting 101 David Schoellhamer Megan Lionberger Bruce Jaffe Neil Ganju Scott Wright Greg Shellenbarger U.S. Geological Survey NASA

2. A sediment budget describes the quantity of sediment Entering the Bay Leaving the Bay Depositing in or eroding from the Bay

3. Who cares? Dredgers: disposal of deposition in ports and channels Regulators and dischargers: sediment associated contaminants and TMDLs Restoration managers: deposition needed for restoration without eroding existing habitat

4. Accounting rules Where: SF Bay from Mallard Island to Golden Gate When: Water years 1955-1990, 1995-2002, and a normal water year 1995-2002 Lifeline: Conservation of mass: inflow-outflow=change in storage Uncertainty: varies by term, Not THE answer – Steve Ritchie

5. Odgen Beeman and Krone 1955-1990

6. New information for 1955-1990 TermOBKNew information Supply from DeltaNo deposition in Delta Delta sediment outflow 1/3 of inflow Bathymetric change Data from navigation charts Data from actual surveys Sand miningAssumed zeroRough estimate

7. Revised 1955-1990 annual budget Units are mass in millions of metric tons per year (~1.5 Mcy)

8. Revised 1955-1990 annual budget Assume Krone Central Bay deposition is ocean sand

9. Revised 1955-1990 annual budget Suspended sediment outflow from conservation of mass (lifeline)

10. Revised 1955-1990 annual budget Sand mining is a very rough estimate

11. 1995-2002 annual budget

12. Box model used to get change in storage and outflow

13. 1995-2002 annual budget Assume no change in supply of ocean sand

14. 1995-2002 was all wet

15. Normal 1995-2002 annual budget Remove water years 1995 and 1998 where possible

16. 1995-2002 1955-1990

17. 1995-2002

18. 1955-1990 1995-2002

19. 1955-1990 1995-2002

20. 1955-1990 1995-2002

21. 1955-1990 1995-2002

22. Implications Sediments disposed of in the ocean may be needed to maintain and restore Bay habitats The Bay bottom will continue to erode and supply legacy contaminants Restoration sites will be depositional and may increase erosion elsewhere Dredging, restoration, and water quality are connected by the sediment budget

23. Most important and most uncertain terms Golden Gate fine suspended sediment outflow (model because difficult to measure) Golden Gate sand supply, 1.2-2.9 MMT/yr (Central Bay bathymetric change) Eroded mass (new surveys, measure bed density) Sediment supply from watershed (±25%)

24. Acknowledgements U.S. Army Corps of Engineers SF Regional Water Quality Control Board California State Coastal Conservancy USGS Priority Ecosystem Science Program USGS Federal/State Cooperative Program Lester McKee Patricia Chambers and Linda Wanczyk