Davis, J. 2023. 2023 RMP Update. SFEI Contribution No. 1148. San Francisco Estuary Institute: Richmond, CA.
The overarching goal of the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) is to answer the highest priority scientific questions faced by managers of Bay water quality. The RMP is an innovative collaboration between the San Francisco Bay Regional Water Quality Control Board, the regulated discharger community, the San Francisco Estuary Institute, and many other scientists and interested parties. The purpose of this document is to provide a concise overview of recent RMP activities and findings, and a look ahead to significant products anticipated in the next two years. The report includes:
a brief summary of some of the most noteworthy findings of this multifaceted Program;
a description of the management context that guides the Program; and
a summary of progress to date and future plans for addressing priority water quality topics.
This document summarizes a study conducted for the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) to re-evaluate the use of the Floating Percentile Method
(FPM) to derive sediment screening guidelines for dredged material reuse in the San Francisco Bay Region. The Long Term Management Strategy (LTMS) has a goal to use at least 40% of the sediment dredged from San Francisco Bay for beneficial reuse (USACE, 1998). The suitability of dredged sediment for beneficial reuse is in part determined by concentrations of toxic pollutants.The San Francisco Regional Water Quality Control Board (SFB-RWQCB) issued draft screening criteria in 2000 to categorize the suitability of sediment for reuse as either “surface” sediment, that may be placed near the surface for re-use in wetlands, or “foundation” sediment, that is buried under sediment that meets surface criteria. Contaminant concentration guidelines for surface sediment are lower than foundation sediment, based on the assumption that biota are more likely to be exposed to surface sediment than deeper foundation sediment.
Sediment is a lifeblood of San Francisco Bay. It serves three key functions: (1) create and maintain tidal marshes and mudflats, (2) transport nutrients and contaminants, and (3) reduce impacts from excessive human-derived nutrients in the Bay. Because of these important roles, we need a detailed understanding of sediment processes in the Bay.
Recent modeling has demonstrated that sediment supply is one of the primary environmental variables that will determine the sustainability of San Francisco Estuary tidal marshes over the next century as sea level rises. Therefore, understanding the environmental controls on sediment flux within the San Francisco Estuary is crucial for optimal planning and management of tidal marsh restoration. Herein, we present suspended-sediment flux estimates from water year (WY) 2009–2016 from the San Francisco Estuary to investigate the environmental controls and impact of the record 2013–2016 California drought. During the recent drought, sediment flux into Lower South Bay, the southernmost subembayment of the San Francisco Estuary, increased by 345% from 114 kt/year from WY 2009 to 2011 to 508 kt/year from WY 2014 to 2016, while local tributary sediment flux declined from 209 to 51 kt/year. Total annual sediment flux from WY 2009 to 2011 and 2014 to 2016 can be predicted by total annual freshwater inflow from the Sacramento-San Joaquin Delta (R2 = 0.83, p < 0.01), the primary source of freshwater input into the San Francisco Estuary. The volume of freshwater inflow from the Sacramento-San Joaquin Delta is hypothesized to affect shoal-to-channel density gradients that affect sediment flux from broad, typically more saline and turbid shoals, to the main tidal-channel seaward of Lower South Bay. During the drought, freshwater inflow from the Sacramento-San Joaquin Delta decreased, and replacement of typically more saline shoal water was reduced. As a result, landward-increasing cross-channel density gradients enhanced shoal-to-channel advective flux that increased sediment available for tidal dispersion and drove an increase in net-landward sediment flux into Lower South Bay.
The 29th RMP Annual Meeting marked the partial return to an in-person meeting after meeting virtually for the previous two years and was held on Monday October 3rd at the David Brower Center in Berkeley, CA. The theme of the meeting was the 50th Anniversary of the Clean Water Act and featured perspectives on the Clean Water Act, as well as updates on the science and management of PCBs, chemicals of emerging concern, sediment, and nutrients.
Video and slide presentations from the meeting are provided below.
Sediment is a lifeblood of San Francisco Bay (Bay). It serves three key functions: (1) create and maintain tidal marshes and mudflats, (2) transport nutrients and contaminants, and (3) reduce impacts from excessive human-derived nutrients in the Bay. Because of these important roles, we need a detailed understanding of sediment processes in the Bay.
This report offers a conceptual understanding of how fine-grained sediment (i.e. silt and finer, henceforth called fine sediment) moves around at different scales within the Bay, now and into the future, to synthesize current knowledge and identify critical knowledge gaps. This information can be used to support Bay sediment management efforts and help prioritize funding for research and monitoring. In particular, this conceptual understanding is designed to inform future San Francisco Bay Regional Monitoring Program (RMP) work under the guidance of the Sediment Workgroup of the RMP for Water Quality in San Francisco Bay, which brings together experts who have worked on many different components of the landscape, including watersheds and tributaries, marshes and mudflats, beaches, and the open Bay. This report describes sediment at two scales: a conceptual understanding of open-Bay sediment processes at the Bay and subembayment scale (Chapter 2); and a conceptual understanding of sediment processes at the baylands scale (Chapter 3). Chapter 4 summarizes the key knowledge gaps and provides recommendations for future studies.
