1. Historical San Francisco Bay Shoreline Perspectives on the Past and Future Predicting the future of San Francisco Bay: learning from history UC Museum of Paleontology Short Course February 6, 2010 Robin Grossinger Historical Ecology Program San Francisco Estuary Institute

2. I. Historical Bayscape

3. 1800

10. Watkins 1861

15. Tidal marsh habitat and plan form geometry at the local scale

16. ► Tidal marshes are more than pickleweed plains ► Extent of tidal channels ► Frequency of marsh pannes, salinas ► Prevalence of sandy beaches ► Upland ecotone

17. II. Shoreline Change

18. 1800

19. 2000

20. Acres x 1000 Open Bay (<MLLW) Intertidal (tidal flat and marsh) Ca 18501800

21. Acres x 1000 Open Bay (<MLLW) Intertidal (tidal flat and marsh) 2000

29. formed since ~1900

33. ~1920

34. Salt ponds and remnant marsh at Ravenswood (San Mateo County), 1993 Shoreline change

35. 1857 versus 1993 erosionaccretion Shoreline change

36. 415 feet

37. III. Our Response

40. The historical practice of using stream-borne sediment to raise marsh elevations: “warping” common in South Bay 75-100 years ago diverted local streams into contained baylands areas

41. “Advantage is taken of this rapid sedimentation both here [San Francisquito Creek] and on Alameda Creek for reclaiming the saltmarsh. The reclamation work is accomplished by building a levee around a certain portion and allowing the flood waters to spread over it and thus drop the sediment at the desired place.” Clark 1924

46. Thank you robin@sfei.org www.sfei.org/HEP