Maureen A. Downing-Kunz

The South Bay Salt Pond Restoration Project (SBSPRP) encompasses over 6,000 hectares of former salt production ponds along the south edge of the San Francisco Bay and represents the largest wetland restoration effort on the west coast of North America. A series of studies associated with Phase 1 (2010–2018) restoration activities that are focused on a historically mercury contaminated slough and series of ponds within the restoration area have recently been completed.

This report brings together the key findings of these loosely coordinated studies and integrates the results into a more comprehensive and holistic product that informs future restoration activities associated with the SBSPRP and elsewhere. This report documents key findings associated with the breach of pond A6: (1) a short-term spike in slough fish (Mississippi silverside) total mercury concentration in lower Alviso Slough; (2) a short-term spike in surface-water particulate total mercury in lower Alviso Slough; (3) significant sediment scour in Alviso Slough adjacent to and downstream of the breach points; (4) a decrease in surface-sediment methylmercury (as a percentage of total mercury) in lower Alviso Slough; (5) the transport of 70 kilograms per year of sediment-associated total mercury into pond A6 during the first 2 years following the breach but with much of this coming from outside of Alviso Slough, presumably from the nearby shallows, Guadalupe Slough, and the larger southern San Francisco Bay area; and (6) a slowing of bed sediment erosion in lower Alviso Slough 3–5 years after the breaching of pond A6.

Although this report is not intended to be prescriptive in terms of the next steps the SBSPRP should or should not take, the totality of the findings presented provide critical process-level information regarding the extent and the duration of spikes in mercury levels in water, sediment, fish, and birds, which appeared to result from the two management actions under study. Thus, these results can be used to anticipate similar ecosystem responses associated with similar management actions that may be considered in the future. We also conclude this report by highlighting unanswered questions associated with mercury dynamics as it relates to the restoration project, and possible future directions for research.

Suggested Citation

Marvin-DiPasquale, M., Slotton, D., Ackerman, J.T., Downing-Kunz, M., Jaffe, B.E., Foxgrover, A.C., Achete, F., and van der Wegen, M., 2022, South San Francisco Bay Salt Pond Restoration Project—A synthesis of Phase-1 mercury studies, U.S. Geological Survey Scientific Investigations Report 2022-5113, 147 p., https://doi.org/10.3133/sir20225113.

First posted March 7, 2023

For additional information, contact:

Director,
Water Resources, Earth System Processes Division
U.S. Geological Survey
345 Middlefield Road
Menlo Park, California, 94025

Keywords

Pond Complex

Alviso

Eden Landing

Ravenswood

Content available here

USGS Publications Warehouse: South San Francisco Bay Salt Pond Restoration Proj…

Continuous Monitoring of Dissolved Oxygen in San Francisco Bay

lorenzof — Wed, 29 May 2019 23:12:21 +0000

Continuous Monitoring of Dissolved Oxygen in San Francisco Bay

lorenzof Wed, 05/29/2019 - 16:12

Poster

Author(s)

Maureen A. Downing-Kunz

Date

Tue, 10/29/2013 - 12:15pm

Sediment: The Macro and Micro of Patterns in the South Bay

admin — Thu, 03 Jan 2019 22:56:04 +0000

Sediment: The Macro and Micro of Patterns in the South Bay

admin Thu, 01/03/2019 - 14:56

Presentation

Author(s)

Maureen A. Downing-Kunz

Date

Tue, 10/10/2017 - 6:40am

Suspended-sediment dynamics in the tidal reach of a San Francisco Bay tributary

admin — Thu, 23 Nov 2017 00:21:53 +0000

Suspended-sediment dynamics in the tidal reach of a San Francisco Bay tributary admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Gregory G. Shellenbarger

Maureen A. Downing-Kunz

David H. Schoellhamer

Date

2014-10-19

Summary

To better understand suspended-sediment transport in a tidal slough adjacent to a large wetland restoration project, we deployed continuously-measuring temperature, salinity, depth, turbidity, and velocity sensors since 2010, and added a dissolved-oxygen sensor in 2012, at a near-bottom location in Alviso Slough (Alviso, California USA). Alviso Slough is the downstream reach of the Guadalupe River and flows into the far southern end of San Francisco Bay. River flow is influenced by the Mediterranean climate, with high flows correlated to episodic winter storms (~85 m3 s-1) and low base flow during the summer (~0.85 m3 s-1). Storms and associated runoff have the greatest influence on sediment flux. Strong spring tides promote upstream sediment flux and weak neap tides have only a small net flux. During neap tides, stratification likely suppresses sediment transport during weaker flood and ebb tides.

Keywords

sediment