Sediment Dynamics in Restored Tidal Wetlands of San Francisco Bay John Callaway & Jennifer Gagnon (USF) Lisa Schile (UC Berkeley) Evyan Borgnis & Tom Parker (SFSU) Donna Ball (HT Harvey & Assoc.) Gene Turner & Charlie Milan (LSU) Past and Present Distribution of SF Bay Wetlands (from San Francisco Estuary Institute) Huge interest in restoration in SF Bay, but … many potential restoration sites (including former salt ponds) have subsided substantially and need to increase elevation to reach threshold elevations for vegetation establishment © David Sanger Theoretical Tidal Wetland Development (from Williams and Orr 2002) Theoretical Tidal Wetland Development Accretion Rate MLLW MTL MHHW Elevation Muzzi Marsh Crissy Field Island Ponds / A21 Pond A6 South Bay Salt Pond Restoration Project Island Ponds / A21 Breached in March 2006 Pond A6 Breached in December 2010 100 m Island Pond Sediment Accretion 250 Southern stations 200 150 100 50 0 Cumulative change in pin height (mm) height pin in change Cumulative 0 10 20 30 40 Time post-breach (months) Island Pond Sediment Accretion 250 Northern stations 200 Southern stations 150 100 50 0 Cumulative change in pin height (mm) height pin in change Cumulative 0 10 20 30 40 Time post-breach (months) Island Pond Sediment Accretion 250 Northern stations 200 Southern stations 150 100 50 0 Cumulative change in pin height (mm) height pin in change Cumulative 0 10 20 30 40 Time post-breach (months) 6 months pre-restoration 36 months 24 months Photos © Cris Benton http://steel.ced.berkeley.edu/research/hidden_ecologies/ Pond A6: Breached December 2010 200 m Pond A6 Sediment Accretion 300 250 200 150 100 50 0 Cumulative change in pin height (mm) height in pin change Cumulative 0 2 4 6 8 10 12 14 Time post-breach (months) Ponds A6 & A21 Sediment Accretion 300 250 200 150 100 50 Pond A21: Southern stations Pond A6 0 Cumulative change in pin height (mm) height pin in change Cumulative 0 10 20 30 40 Time post-breach (months) Muzzi Marsh Crissy Field Island Ponds / A21 Pond A6 Muzzi Marsh: Restored 1976 100 m SETs & Markers Sedimentation Erosion Table (SET) marsh surface feldspar marker horizon Muzzi Marsh Sediment Accretion 12 Low Marsh 10 Mid Marsh High Marsh 8 6 4 2 0 Cumulative Sediment Accretion (mm) Accretion Sediment Cumulative 0 2 4 6 8 10 12 14 Cumulative change in pin height (mm) Crissy Field Marsh Restoration Project (from Robert Campbell Photography) Crissy Field Marsh: Restored 1999 100 m Transect #3 Transect #1 Transect #2 Crissy Field Marsh Sediment Accretion 80 HIGH STATIONS 40 0 -40 -80 80 MID STATIONS 40 0 Transect 1 Transect 2 -40 Transect 3 80 -80 LOW STATIONS 40 Cumulative change in elevation (mm)Cumulativein elevation change 0 -40 -80 2000 2001 2002 2003 2004 2005 2006 2007 2008 (from Kristen Ward, NPS) Petaluma River Marsh Coon Island Rush Ranch China Camp Browns Island Muzzi Marsh Crissy Field Whale’s Tail Marsh Island Ponds Greco Island Pond A6 137 210 Cs Activity (dpm/g) Pb Activity (dpm/g) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 0 -10 -10 -20 -20 -30 1963 -30 Depth (cm) Depth -40 -40 -50 -50 100 m Low station Mid station High station 1.0 137Cs 210 0.8 2 Browns Island Pb 0.6 2 2 Natural 0.4 2 2 1 0.2 1.0 0.0 0.8 Rush Ranch Wetland 0.6 0.4 2 2 2 2 2 2 0.2 Accretion Rates 0.0 1.0 3 0.8 Coon Island 0.6 3 0.4 3 4 2 • 37 dated cores using 2 0.2 1.0 0.0 both 137Cs and 210Pb (out 0.8 Petaluma River Marsh 0.6 of 48 cores collected)! 0.4 1 1 2 2 2 0.2 2 0.0 1.0 Accretion Rate (cm/yr) Rate Accretion • Very consistent rates of 0.8 2 China Camp 0.6 2 accretion in mid and 2 2 0.4 2 2 0.2 high marsh: ~0.3 cm/yr 1.0 0.0 0.8 2 Whales Tail 0.6 1 1 • Low marsh: four sites 0.4 1 1 0.2 ~0.6 cm/yr using 137Cs 0.0 Low Mid High Elevation (Callaway et al., in press) Marsh Suspended Sediment Concentrations Mean Suspended Sediment Concentration (mg/L) Concentration Sediment Suspended Mean (J. Gagnon, USF) Summary of Accretion Rates across Sites Sites Range of accretion rates Pond A6 > 200 mm/yr Island Ponds 10 to 100 mm/yr Muzzi Marsh 3 to 10 mm/yr Crissy Field -5 to 4 mm/yr Low marsh (natural) Up to 6 mm/yr Mid and high marsh (natural) 3 mm/yr Theoretical Tidal Wetland Development Accretion Rate MLLW MTL MHHW Elevation Theoretical Tidal Wetland Development A6 200 mm/yr Island Ponds 100 mm/yr Natural Natural mid & low marsh high marsh Accretion Rate Lower 6 mm/yr 3 mm/yr Muzzi Marsh 10 mm/yr Elevation Conclusions • Rapid sediment accumulation at low elevations in most restored marshes • Results closely match expectations of marsh development over time • Natural wetlands are keeping pace with current rates of SLR • High suspended sediment concentrations within SF Bay marshes Acknowledgments .Gordon and Betty Moore Foundation .South Bay Salt Pond Project & the Resources Legacy Fund .San Francisco Bay Conservation and Development Commission & US EPA .Coastal Conservancy Association .USF Faculty Development Fund .Many USF and SFSU students .