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Lin, D.; Davis, J. 2018. Support for Sediment Bioaccumulation Evaluation: Toxicity Reference Values for the San Francisco Bay. SFEI Contribution No. 916. San Francisco Estuary Institute : Richmond, CA.
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Wang, M.; Kinyua, J.; Jiang, T.; Sedlak, M.; McKee, L. J. .; Fadness, R.; Sutton, R.; Park, J. - S. 2022. Suspect Screening and Chemical Profile Analysis of Storm-Water Runoff Following 2017 Wildfires in Northern California. Environmental Toxicology and Chemistry . SFEI Contribution No. 1089.

The combustion of structures and household materials as well as firefighting during wildfires lead to releases of potentially hazardous chemicals directly into the landscape. Subsequent storm-water runoff events can transport wildfire-related contaminants to downstream receiving waters, where they may pose water quality concerns. To evaluate the environmental hazards of northern California fires on the types of contaminants in storm water discharging to San Francisco Bay and the coastal marine environment, we analyzed storm water collected after the northern California wildfires (October 2017) using a nontargeted analytical (NTA) approach. Liquid chromatography quadrupole time-of-flight mass spectrometric analysis was completed on storm-water samples (n = 20) collected from Napa County (impacted by the Atlas and Nuns fires), the city of Santa Rosa, and Sonoma County (Nuns and Tubbs fires) during storm events that occurred in November 2017 and January 2018. The NTA approach enabled us to establish profiles of contaminants based on peak intensities and chemical categories found in the storm-water samples and to prioritize significant chemicals within these profiles possibly attributed to the wildfire. The results demonstrated the presence of a wide range of contaminants in the storm water, including surfactants, per- and polyfluoroalkyl substances, and chemicals from consumer and personal care products. Homologs of polyethylene glycol were found to be the major contributor to the contaminants, followed by other widely used surfactants. Nonylphenol ethoxylates, typically used as surfactants, were detected and were much higher in samples collected after Storm Event 1 relative to Storm Event 2. The present study provides a comprehensive approach for examining wildfire-impacted storm-water contamination of related contaminants, of which we found many with potential ecological risk. Environ Toxicol Chem 2022;00:1–14. © 2022 SETAC

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Livsey, D. N.; Downing-Kunz, M. A.; Schoellhamer, D. H.; Manning, A. J. 2020. Suspended Sediment Flux in the San Francisco Estuary: Part I—Changes in the Vertical Distribution of Suspended Sediment and Bias in Estuarine Sediment Flux Measurements. Estuaries and Coasts . SFEI Contribution No. 990.

In this study, we investigate how changes in the vertical distribution of suspended sediment affect continuous suspended sediment flux measurements at a location in the San Francisco Estuary. Current methods for measuring continuous suspended sediment flux estimates relate continuous estimates of suspended-sediment concentration (SSC) measured at-a-point (SSCpt) to discrete cross-section measurements of depth-averaged, velocity-weighted SSC (SSCxs). Regressions that compute SSCxs from continuous estimates of SSCpt require that the slope between SSCpt and SSCxs, controlled by the vertical distribution of SSC, is fixed. However, in tidal systems with suspended cohesive sediment, factors that control the vertical SSC profile—vertical turbulent mixing and downward settling of suspended sediment mediated by flocculation of cohesive sediment—constantly vary through each tide and may exhibit systematic differences between flood and ebb tides (tidal asymmetries in water velocity or particle size). We account for changes in the vertical SSC profile on estimates of SSCxs using time series of the Rouse number of the Rouse-Vanoni-Ippen equation combined with optical turbidity measurements, a surrogate for SSCpt, to predict SSCxs from 2009 to 2011 and 2013. Time series of the Rouse number were estimated by fitting the Rouse-Vanoni-Ippen equation to SSC estimated from optical-turbidity measurements taken at two elevations in the water column. When accounting for changes in the vertical SSC profile, changes in not only the magnitude but also the direction of cumulative sediment-flux measurements were observed. For example, at a mid-depth sensor, sediment flux estimates changed from − 319 kt (± 65 kt, negative indicating net seaward transport) to 482 kt (± 140 kt, positive indicating net landward transport) for 2009–2011 and from − 388 kt (± 140 kt) to 1869 kt (± 406 kt) for 2013–2016. At the study location, estimation of SSCxs solely from SSCpt resulted in sediment flux values that were underestimates on flood tides and overestimates on ebb tides. This asymmetry is driven by covariance between water velocity and particle settling velocity (Ws) with larger Ws on flood compared to ebb tides. Results of this study indicate that suspended-sediment-flux measurements estimated from point estimates of SSC may be biased if systematic changes in the vertical distribution of SSC are unaccounted for.

Livsey, D. N.; Downing-Kunz, M. A.; Schoellhamer, D. H.; Manning, A. 2020. Suspended-sediment Flux in the San Francisco Estuary; Part II: the Impact of the 2013–2016 California Drought and Controls on Sediment Flux. Estuaries and Coasts. SFEI Contribution No. 1137. Estuaries and Coasts.

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.

Gilbreath, A. N.; Stark, K.; Pearce, S.; Mckee, L. 2023. Suspended Sediment Loads Analysis of Four Creeks in the San Francisco Bay Area. SFEI Contribution No. 1134. San Francisco Estuary Institute: Richmond, CA.
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David, N. 2009. Sustainable Cotton Project. SFEI Contribution No. 592. San Francisco Estuary Institute: Oakland, Ca.
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Beagle, J.; Richey, A.; Hagerty, S.; Salomon, M.; Askevold, R. A.; Grossinger, R. M.; Reynolds, P.; McClain, C.; Spangler, W.; Quinn, M.; et al. 2017. Sycamore Alluvial Woodland: Habitat Mapping and Regeneration Study. SFEI Contribution No. 816.

This study investigates the relative distribution, health, and regeneration patterns of two major stands of sycamore alluvial woodland (SAW), representing managed and natural settings. Using an array of ecological and geomorphic field analyses, we discuss site characteristics favorable to SAW health and regeneration, make recommendations for restoration and management, and identify next steps. Findings from this study will contribute to the acquisition, restoration, and improved management of SAW as part of the Santa Clara Valley Habitat Plan (VHP).

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H. T. Harvey & Associates. 2023. Sycamore Alluvial Woodland Pilot Study Implementation Guidelines. Prepared for Zone 7 Water Agency and US Environmental Protection Agency’s Water Quality Improvement Fund. In collaboration with San Francisco Estuary Institute.

This document supports planting-based approaches for sycamore enhancement by providing site-level revegetation techniques for installing, maintaining and monitoring sycamore plantings.

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Pearce, S.; Whipple, A.; Harris, K.; Lee, V.; Hegstad, R.; McClain, C. 2023. Sycamore Alluvial Woodland Restoration and Enhancement Suitability Study. In collaboration with Alameda County Flood Control and Water Conservation District, Zone 7. Prepared for the US Environmental Protection Agency’s Water Quality Improvement Fund. SFEI Contribution No. 1128. San Francisco Estuary Institute: Richmond, CA.

The “Sycamore Alluvial Woodland Restoration and Enhancement Suitability Study” addresses distribution and regeneration patterns and restoration strategies of sycamore alluvial woodland (SAW) habitat, a unique and relatively rare native vegetation community adapted to California’s intermittent rivers and streams. The report was produced by SFEI and H. T. Harvey & Associates, as part of the US EPA Water Quality Improvement Fund Preparing for the Storm grant, led by Zone 7 Water Agency.

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Moran, K.; Miller, E.; Mendez, M.; Moore, S.; Gilbreath, A.; Sutton, R.; Lin, D. 2021. A Synthesis of Microplastic Sources and Pathways to Urban Runoff. SFEI Contribution No. 1049. San Francisco Estuary Institute: Richmond, CA.

California Senate Bill 1263 (2018) tasks the Ocean Protection Council (OPC) with leading statewide efforts to address microplastic pollution, and requires the OPC to adopt and implement a Statewide Microplastics Strategy related to microplastic materials that pose an emerging concern for ocean health. Key questions remain about the sources and pathways of microplastics, particularly to urban runoff, to inform an effective statewide microplastics management strategy. The OPC funded this work to inform these microplastics efforts. The purpose of this project was to build conceptual models that synthesize and integrate our current understanding of microplastic sources and pathways to urban runoff in order to provide future research priorities that will inform how best to mitigate microplastic pollution. Specifically, we developed conceptual models for cigarette butts and associated cellulose acetate fibers (Section 2), fibers other than cellulose acetate (Section 3), single-use plastic foodware and related microplastics (Section 4), and tire particles (Section 5), which were prioritized based on findings from the recent urban stormwater monitoring of microplastics in the San Francisco Bay region. Conceptual models specific to each of these particle types are valuable tools to refine source identification and elucidate potential source-specific data gaps and management options.

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Cohen, A. N. 2007. Tanaidacea in The Light & Smith Manual: Intertidal Invertebrates of the California and Oregon Coast. In The Light & Smith Manual: Intertidal Invertebrates of the California and Oregon Coast.. Carlton, J. T., Ed.. The Light & Smith Manual: Intertidal Invertebrates of the California and Oregon Coast. University of California Press: Berkeley, Ca.
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May, M. D.; Kramer, K. S. 1993. Teaching About the San Francisco Bay and Delta - An Activities and Resource Guide, 2nd Ed. SFEI Contribution No. 174. San Francisco Estuary Institute: Richmond, Ca. p 500.
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Davis, J. A.; Yoon, J. 1999. Technical Report of the Chlorinated Hydrocarbon Workgroup. San Francisco Estuary Institute: Richmond, CA.
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Ruhl, C. A.; Schoellhamer, D. H. 1998. Technical Report of the San Francisco Estuary Regional Monitoring Program for Trace Substances. SFEI Contribution No. 375. San Francisco Estuary Institute: Richmond, CA.
Davis, J. A.; Gunther, A. J.; Abu-Saba, K. E. 2001. Technical Report of the Sources, Pathways, and Loadings Workgroup. SFEI Contribution No. 266. San Francisco Estuary Institute: Richmond, CA.
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Flegal, A. R.; Abu-Saba, K. E. 1997. Temporally variable freshwater sources of dissolved chromium to the San Francisco Bay estuary. Environmental Science and Technology 31, 3455-3460 . SFEI Contribution No. 197.
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Cohen, A. N.; Woo, M.; Jabari, E. 2001. Testing Ballast Water Treatment at a Municipal Wastewater Treatment Plant. California Sea Grant/National Sea Grant College Program, La Jolla CA.
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Rochman, C. M.; Munno, K.; Box, C.; Cummins, A.; Zhu, X.; Sutton, R. 2020. Think Global, Act Local: Local Knowledge Is Critical to Inform Positive Change When It Comes to Microplastics. Environmental Science & Technology . SFEI Contribution No. 1024.

Microplastic contamination in the marine environment is a global issue. Across the world, policies at the national and international level are needed to facilitate the scale of change needed to tackle this significant problem. However, sources and patterns of plastic contamination vary around the world, and the most pressing actions differ from one location to another. Therefore, local policies are a critical part of the solution; recognizing local sources will enable mitigations with measurable impacts. Here, we highlight how investigating the contamination comprehensively in one location can inform relevant mitigation strategies that can be transferred globally. We examine the San Francisco Bay in California, USA—the largest estuary on the West Coast of the Americas, and home to over 7 million people. The local contamination of microplastics in surface water, sediments, and fish from this urban bay is reportedly higher than many places studied to date.(1) This example demonstrates the value of local monitoring in identifying sources, informing local mitigation strategies and developing an array of solutions to stem the multifaceted tide of plastic pollution entering our global oceans.

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Cohen, A. N. 1989. Threatened in the nest. Pacific Discovery (Calif. Acad. Sci.) 42, 6-13.
Greenfield, B. K. 2004. Three mechanical shredders evaluated for controlling water hyacinth (California). Ecological Restoration 22, 300-301 . SFEI Contribution No. 463.
Greenfield, B. K.; Davis, J. A.; Collins, J. N.; Grenier, J. Letitia. 2002. The tidal marsh food web. SFEI Contribution No. 472. University of California: Berkeley, CA. p 12 pp.
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Safran, S. M. 2015. The Tijuana River Valley: An Ecological Look into the Past.

Hot springs in the Tijuana River? Antelope by the beach? Zip-lines over the international border?
Come find out what the Tijuana River Valley looked like in the not-so-distant past and how the river, estuary, and surrounding areas have changed over the past two centuries. Hear how researchers “recreated” the historical landscape and how this information helps us to better plan for the future.

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Safran, S. M.; Baumgarten, S. A.; Beller, E. E.; Crooks, J. A.; Grossinger, R. M.; Lorda, J.; Longcore, T. R.; Bram, D. L.; Dark, S. J.; Stein, E. D.; et al. 2017. Tijuana River Valley Historical Ecology Investigation. Prepared for the State Coastal Conservancy. A Report of SFEI-ASC’s Resilient Landscapes Program. SFEI Contribution No. 760. San Francisco Estuary Institute - Aquatic Science Center : Richmond, CA. p 230.

The Tijuana River Valley Historical Ecology Investigation addresses a regional data gap by reconstructing the landscape and ecosystem characteristics of the river valley prior to the major modifications of the late 19th and 20th centuries. The research presented here, funded by the California State Coastal Conservancy, supplies foundational information at the regional and system scale about how the Tijuana Estuary, River, and valley looked and functioned in the recent past, as well as how they have changed over time. The ultimate goal of this study is to provide a new tool and framework that, in combination with contemporary research and future projections, can support and guide ongoing restoration design, planning, and management efforts in the valley.

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Moran, K.; Sutton, R. 2023. Tire Wear: Emissions Estimates and Market Insights to Inform Monitoring Design. Gilbreath, A., Méndez, M., Lin, D., Eds.. SFEI Contribution No. 1109. San Francisco Estuary Institute: Richmond, CA.

Every vehicle on the road sheds tiny particles from its rubber tires into the environment. Tire wear is one of the top sources of microplastic releases to the environment. Tire wear also disperses tire-related chemicals into the environment. SFEI studies supported by the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) and others have found tire wear particles and tire-related chemicals in San Francisco Bay and its small tributaries, which drain the Bay watershed’s local urban areas. The RMP has developed a short-term multi-year plan of potential special studies (“Tires Strategy”) that responds to recent data revealing the magnitude of tire particle and chemical emissions and their potential toxicity to aquatic organisms.

This article is available upon request. Please message [email protected] for the materials.

Pearce, S.; Mckee, L.; Whipple, A.; Church, T. 2021. Towards a Coarse Sediment Strategy for the Bay Area. SFEI Contribution No. 1032. San Francisco Estuary Institute: Richmond, CA.

Historic and current regional management of watersheds and channels for water supply and flood control across the San Francisco Bay Area has cut off much of the coarse sediment that was historically delivered to the Bay. Here we define coarse sediment as having grain sizes larger than 0.0625 mm, which includes sand, gravel and even cobble, as opposed to fine sediment that includes clay, mud and silt. Future projections indicate that sediment supply will not meet the demand from extant and restored tidal marshes to keep up with sea level rise.


The US EPA Water Quality Improvement Fund Preparing for the Storm grant has funded the Zone 7 Water Agency, the San Francisco Estuary Institute and the San Francisco Bay Joint Venture to support the future development of a successful regional coarse sediment reuse strategy. Development of such a strategy requires an understanding of logistical and regulatory hurdles and identification of key strategies for breaking down barriers. One potential solution for meeting the sediment demand along the Bay margin is to utilize coarse sediment that is removed from flood control channels by public agencies. To-date, very little of this sediment that is removed is beneficially reused for restoration along the Bay shoreline. The current economic and regulatory framework around sediment removal presents many challenges, barriers and lack of incentives for agencies to reuse their sediment.

This document represents a step forward towards beneficially reusing coarse flood control channel sediment by outlining reuse challenges, and identifying incentives for participation and potential solutions.

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Smith, R.; Thompson, B. 1994. Towards an Optimal Sampling Design for the RMP. SFEI Contribution No. 6. San Francisco Estuary Institute: Richmond, CA.
Phillips, D. J. H. 1987. Toxic Contaminants in the San Francisco Bay-Delta and their Possible Biological Effects. SFEI Contribution No. 145. Aquatic Habitat Institute: Richmond, CA. p 472.
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Flegal, A. R.; Sanudo-Wilhelmy, S. A. 1996. Trace metal concentrations in the surf zone and in coastal waters off Baja California, Mexico. Environmental Science and Technology 30, 1575-1580 . SFEI Contribution No. 195.
Jarman, W. M.; Bacon, C.; Owen, B. 1999. Trace Organic Sampler Intercalibration Results. SFEI Contribution No. 34. San Francisco Estuary Institute: Richmond, CA.
Safran, S. M.; Hagerty, S.; Robinson, A.; Grenier, L. 2018. Translating Science-Based Restoration Strategies into Spatially-Explicit Restoration Opportunities in the Delta (2018 Bay-Delta Science Conference Presentation).

In a previous report titled “A Delta Renewed” we offered a collection of guidelines for science-based ecological restoration in the Sacramento-San Joaquin Delta that emphasized restoring or emulating natural processes, anticipating future changes associated with climate change, establishing appropriate configurations of habitat types at the landscape scale, and utilizing a variety multi-benefit management strategies. In this talk, we present on our recent work to support regional restoration planning efforts by developing a repeatable process for using these guidelines to identify spatially-explicit restoration opportunities. The process is largely GIS-based and utilizes spatial data on existing land cover and conservation status, habitat configuration (including patch sizes and distances), surface elevations (including depth of subsidence), and future changes in tidal elevations associated with sea-level rise.  By distilling generalized guidelines into spatially-explicit opportunities, we hope to provide a practical tool for incorporating science into planning. To that end, these new methods are currently being piloted through planning efforts focused on the Central Delta Corridor and the McCormack Williamson Tract, and are also being used to assist with the quantification of ecological restoration potential in the Delta Plan Ecosystem Amendment.

Presentation recording: available here.

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Pearce, S. A.; Stark, K. 2023. Translating Sediment Science Into Action: Documenting Beneficial Sediment Reuse. SFEI Contribution No. 1124. San Francisco Estuary Institute: Richmond, CA.

The Preparing for the Storm project, led by Zone 7 Water Agency (Zone 7) and funded by the US Environmental Protection Agency (EPA) Water Quality Improvement Fund, aims to develop science-based plans, strengthen existing and new partnerships, and pilot new methodologies for tackling these issues surrounding coarse sediment. As a task within this larger project, this report describes four projects in the East Bay that serve as case studies for beneficial reuse of sediment. Each example highlights a project with sediment that could be reused (in lieu of landfilling) or a project that needs additional sediment and could benefit from deliveries of sediment that normally would not have been beneficially reused.

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Zi, T.; Whipple, A.; Kauhanen, P.; Spotswood, E.; Grenier, L.; Grossinger, R.; Askevold, R. 2021. Trees and Hydrology in Urban Landscapes. SFEI Contribution No. 1034. San Francisco Estuary Institute: Richmond, CA.

Effective implementation of urban greening strategies is needed to address legacies of landscape change and environmental degradation, ongoing development pressures, and the urgency of the climate crisis. With limited space and resources, these challenges will not be met through single-issue or individual-sector management and planning. Increasingly, local governments, regulatory agencies, and other urban planning organizations in the San Francisco Bay Area are expanding upon the holistic, portfolio-based, and multi-benefit approaches.

This effort, presented in the Trees and Hydrology in Urban Landscapes report, seeks to build links between stormwater management and urban ecological improvements by evaluating how complementary urban greening activities, including green stormwater infrastructure (GSI) and urban tree canopy, can be integrated and improved to reduce runoff and contaminant loads in stormwater systems. This work expands the capacity for evaluating engineered GSI and non-engineered urban greening within a modeling and analysis framework, with a primary focus on evaluating the hydrologic benefit of urban trees. Insights can inform stormwater management policy and planning. 

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Lin, D.; Hamilton, C.; Hobbs, J.; Miller, E.; Sutton, R. 2023. Triclosan and Methyl Triclosan in Prey Fish in a Wastewater-influenced Estuary. Environmental Toxicology and Chemistry . SFEI Contribution No. 1112.

While the antimicrobial ingredient triclosan has been widely monitored in the environment, much less is known about the occurrence and toxicity of its major transformation product, methyl triclosan. An improved method was developed and validated to effectively extract and quantify both contaminants in fish tissue and was used to characterize concentrations in small prey fish in areas of San Francisco Bay where exposure to triclosan via municipal wastewater discharges was expected to be highest. Concentrations of triclosan (0.44–57 ng/g ww, median 1.9 ng/g ww) and methyl triclosan (1.1–200 ng/g ww, median 36 ng/g ww) in fish tissue decreased linearly with concentrations of nitrate in site water, used as indicators of wastewater influence. The total concentrations of triclosan and methyl triclosan measured in prey fish were below available toxicity thresholds for triclosan, but there are few ecotoxicological studies to evaluate impacts of methyl triclosan. Methyl triclosan represented up to 96% of the total concentrations observed. These results emphasize the importance of monitoring contaminant transformation products, which can be present at higher levels than the parent compound.

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Tian, Z.; Zhao, H.; Peter, K. T.; Gonzalez, M.; Wetzel, J.; Wu, C.; Hu, X.; Prat, J.; Mudrock, E.; Hettinger, R.; et al. 2020. A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon. Science.

In U.S. Pacific Northwest coho salmon (Oncorhynchus kisutch), stormwater exposure annually causes unexplained acute mortality when adult salmon migrate to urban creeks to reproduce. By investigating this phenomenon, we identified a highly toxic quinone transformation product of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), a globally ubiquitous tire rubber antioxidant. Retrospective analysis of representative roadway runoff and stormwater-affected creeks of the U.S. West Coast indicated widespread occurrence of 6PPD-quinone (<0.3 to 19 micrograms per liter) at toxic concentrations (median lethal concentration of 0.8 ± 0.16 micrograms per liter). These results reveal unanticipated risks of 6PPD antioxidants to an aquatic species and imply toxicological relevance for dissipated tire rubber residues.

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Sutton, R.; Lin, D.; Sedlak, M.; Box, C.; Gilbreath, A.; Holleman, R.; Miller, L.; Wong, A.; Munno, K.; Zhu, X.; et al. 2019. Understanding Microplastic Levels, Pathways, and Transport in the San Francisco Bay Region. SFEI Contribution No. 950. San Francisco Estuary Institute: Richmond, CA.

Microplastics (particles less than 5 mm) are ubiquitous and persistent pollutants in the ocean and a pervasive and preventable threat to the health of marine ecosystems. Microplastics come in a wide variety of shapes, sizes, and plastic types, each with unique physical and chemical properties and toxicological impacts. Understanding the magnitude of the microplastics problem and determining the highest priorities for mitigation require accurate measures of microplastic occurrence in the environment and identification of likely sources.

To develop critical baseline data and inform solutions, the San Francisco Estuary Institute and the 5 Gyres Institute have completed the first comprehensive regional study of microplastic pollution in a major estuary. This project supported multiple scientific components to develop improved knowledge about and characterization of microparticles and microplastics in San Francisco Bay and adjacent National Marine Sanctuaries, with the following objectives:

  1. Contribute to the development and standardization of sample collection and analysis methodology for microplastic transportation research.
  2. Determine a baseline for future monitoring of microplastics in San Francisco Bay surface water, sediment, and fish, and in ocean waters outside the Golden Gate.
  3. Characterize pathways by which microplastics enter the Bay, including urban stormwater and treated wastewater effluent.
  4. Investigate the contribution of Bay microplastics to the adjacent National Marine Sanctuaries through computer simulations.
  5. Communicate findings to regional stakeholders and the general public through meetings and educational materials.
  6. Facilitate evaluation of policy options for San Francisco Bay, with recommendations on source reduction.

This document presents the findings of this three-year project. A companion document, “San Francisco Bay Microplastics Project: Science-Supported Solutions and Policy Recommendations,” has been developed by 5 Gyres using the findings of this study (Box and Cummins, 2019).

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Lowe, S.; Salomon, M.; Pearce, S.; Josh Collins; Titus, D. 2016. Upper Pajaro River Watershed Condition Assessment 2015. Technical memorandum prepared for the Santa Clara Valley Water District - Priority D5 Project. SFEI Contribution No. 810. San Francisco Estuary Institute: Richmond, CA. p 60.

In 2015 The Santa Clara Valley Water District and it's consultants conducted a watershed wide survey to characterize the distribution and abundance of the aquatic resources within the upper Pajaro River watershed wtihin Santa Clara County, CA based on available GIS datasets, and to assess the overall ecological condition of streams within the watershed based on a statistically based random sample design and the California Rapid Assessment Method for streams (CRAM).

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Bruland, K. W.; Phinney, J. T. 1994. Uptake of lipophilic organic Cu, Cd, and Pb complexes in the coastal diatom, Thalassiosira Weissflogii. Environmental Science and Technology 28, 1781-1790 . SFEI Contribution No. 179.
Hagerty, S.; Spotswood, E.; McKnight, K.; Grossinger, R. M. 2019. Urban Ecological Planning Guide for Santa Clara Valley. SFEI Contribution No. 941. San Francisco Estuary Institute: Richmond, CA.

This document provides some of the scientific foundation needed to guide planning for urban biodiversity in the Santa Clara Valley region, grounded in an understanding of landscape history, urban ecology and local setting. It can be used to envision the ecological potential for individual urban greening projects, and to guide their siting, design and implementation. It also can be used to guide coordination of projects across the landscape, with the cooperation of a group of stakeholders (such as multiple agencies, cities and counties). Users of this report may include a wide range of entities, such as local nonprofits, public agencies, city planners, and applicants to the Open Space Authority’s Urban Open Space Grant Program.
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Wheeler, M.; Stoneburner, L.; Spotswood, E.; Grossinger, R.; Barar, D.; Randisi, C. 2022. An Urban Forest Master Plan for East Palo Alto. SFEI Contribution No. 1071. San Francisco Estuary Institute: Richmond, CA.
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Werbowski, L. M.; Gilbreath, A.; Munno, K.; Zhu, X.; Grbic, J.; Wu, T.; Sutton, R.; Sedlak, M.; Deshpande, A. D.; Rochman, C. M. 2021. Urban Stormwater Runoff: A Major Pathway for Anthropogenic Particles, Black Rubbery Fragments, and Other Types of Microplastics to Urban Receiving Waters. Environmental Science and Technology Water . SFEI Contribution No. 1040.

Stormwater runoff has been suggested to be a significant pathway of microplastics to aquatic habitats; yet, few studies have quantified microplastics in stormwater. Here, we quantify and characterize urban stormwater runoff from 12 watersheds surrounding San Francisco Bay for anthropogenic debris, including microplastics. Depth-integrated samples were collected during wet weather events. All stormwater runoff contained anthropogenic microparticles, including microplastics, with concentrations ranging from 1.1 to 24.6 particles/L. These concentrations are much higher than those in wastewater treatment plant effluent, suggesting urban stormwater runoff is a major source of anthropogenic debris, including microplastics, to aquatic habitats. Fibers and black rubbery fragments (potentially tire and road wear particles) were the most frequently occurring morphologies, comprising ∼85% of all particles across all samples. This suggests that mitigation strategies for stormwater should be prioritized. As a case study, we sampled stormwater from the inlet and outlet of a rain garden during three storm events to measure how effectively rain gardens capture microplastics and prevent it from contaminating aquatic ecosystems. We found that the rain garden successfully removed 96% of anthropogenic debris on average and 100% of black rubbery fragments, suggesting rain gardens should be further explored as a mitigation strategy for microplastic pollution.

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