Multi-box mass balance model of PFOA and PFOS in different regions of San Francisco Bay

Chemosphere (Elsevier) | August 3rd, 2020

We present a model to predict the long-term distribution and concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in estuaries comprisi

We present a model to predict the long-term distribution and concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in estuaries comprising multiple intercommunicated sub-embayments. To that end, a mass balance model including rate constants and time-varying water inputs was designed to calculate levels of these compounds in water and sediment for every sub-embayment. Subsequently, outflows and tidal water exchanges were used to interconnect the different regions of the estuary. To calculate plausible risks to population, outputs of the model were used as inputs in a previously designed model to simulate concentrations of PFOA and PFOS in a sport fish species (Cymatogaster aggregata). The performance of the model was evaluated by applying it to the specific case of San Francisco Bay, (California, USA), using 2009 sediment and water sampled concentrations of PFOA and PFOS in North, Central and South regions. Concentrations of these compounds in the Bay displayed exponential decreasing trends, but with different shapes depending on region, compound, and compartment assessed. Nearly stable PFOA concentrations were reached after 50 years, while PFOS needed close to 500 years to stabilize in sediment and fish. Afterwards, concentrations stabilize between 4 and 23 pg/g in sediment, between 0.02 and 44 pg/L in water, and between 7 and 104 pg/g wet weight in fish, depending on compound and region. South Bay had the greatest final concentrations of pollutants, regardless of compartment. Fish consumption is safe for most scenarios, but due to model uncertainty, limitations in monthly intake could be established for North and South Bay catches.

National Marine Fisheries Service Biological Opinion for the Long-Term Operations of the Central Valley Project and State Water Project

National Marine Fisheries Service (NMFS) | June 3rd, 2009

The purpose of this document is to present NOAA’s National Marine Fisheries Service’s (NMFS) biological and conference opinion (Opinion), about whether the U.S. Burea

The purpose of this document is to present NOAA’s National Marine Fisheries Service’s (NMFS) biological and conference opinion (Opinion), about whether the U.S. Bureau of Reclamation’s (Reclamation) proposed long-term operations of the Central Valley Project (CVP), operated in coordination with the State Water Project (SWP; hereafter referred to as CVP/SWP operations, the proposed action, or the project), is likely to jeopardize the continued existence of the following species: Endangered Sacramento River winter-run Chinook salmon (Oncorhynchus tshawytscha, hereafter referred to as winter-run) Threatened Central Valley spring-run Chinook salmon (O. tshawytscha, hereafter referred to as spring-run) Threatened Central Valley (CV) steelhead (O. mykiss) Threatened Central California Coast (CCC) steelhead (O. mykiss) Threatened Southern Distinct Population Segment (DPS) of North American green sturgeon (Acipenser medirostris, hereafter referred to as Southern DPS of green sturgeon) Endangered Southern Resident killer whales (Orcinus orca, hereafter referred to as Southern Residents) or destroy or adversely modify the designated critical habitat of the above salmon and steelhead species, or proposed critical habitat for Southern DPS of green sturgeon. This Opinion is based on the best scientific and commercial information available.

Native and alien fishes in a California estuarine marsh: twenty-one years of changing assemblages

American Fisheries Society (AFS) | September 30th, 2002

We used monthly otter trawling and beach seining to sample the fishes of Suisun Marsh in the San Francisco Estuary from 1979 to 1999. We collected nearly 173,000 fish, mo

We used monthly otter trawling and beach seining to sample the fishes of Suisun Marsh in the San Francisco Estuary from 1979 to 1999. We collected nearly 173,000 fish, mostly young of the year, representing 28 native species and 25 alien species. Catch data were related to temperature, salinity, water transparency, and several measures of freshwater inflow into the marsh. Species abundance and distribution within the marsh were the product of several interacting factors: (1) the timing and place of reproduction of the abundant resident species, (2) past reproductive success, (3) habitat differences among sloughs, and (4) physiological tolerance. We did not find consistent groups of potentially interacting species, although some native species showed weak concordance in abundance. The lack of persistent fish assemblages is related to the naturally fluctuating environmental conditions of the estuary, the overall decline in fish abundance through time, and the frequent invasions of alien fishes and invertebrates. Our results suggest that the fish assemblages in Suisun Marsh will continue to be unpredictable until estuarine processes approach their historic range of variability and alien invasions are halted.

Necessity for Comprehensive Adjudication of Water Rights on the Sacramento and San Joaquin Rivers in Aid of the Central Valley Project

U.S. Government Publishing Office (GPO) | November 30th, 1942

Neonicotinoids and their Degradates in San Francisco Bay Water

San Francisco Estuary Institute (SFEI) | July 1st, 2020

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) screened Bay waters for neonicotinoid pesticides, comparing levels to toxicity thresholds to

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) screened Bay waters for neonicotinoid pesticides, comparing levels to toxicity thresholds to inform placement of this class of emerging contaminants within the tiered risk-based framework. Neonicotinoids are one of the most widely used classes of insecticides in the world. Given their widespread use in agricultural and urban environments, and ubiquitous detections in surface waters, there is growing concern about consequences for non-target species such as aquatic invertebrates, insects, birds, and fish. In the summer of 2017, open Bay water samples were collected during the RMP Status and Trends Water Cruise. Samples were analyzed for 19 neonicotinoids and metabolites. The only neonicotinoid detected was imidacloprid, an active ingredient used in both urban and agricultural applications. Imidacloprid was detected at a single site above the method detection limits (2.2-2.6 ng/L) in Lower South Bay at a level of 4.2 ng/L. This value is within the range of concentrations found in a separate RMP study in water samples collected from the South and Lower South Bay margins in 2017. Imidacloprid was detected at 3 of 12 of the margin sites at levels between 3.9 and 11 ng/L; no other neonicotinoids were detected. Of note, these RMP studies appear to represent the first evaluation of ambient neonicotinoid concentrations in an estuarine environment in the nation. Two significant pathways of imidacloprid contamination to the Bay are treated wastewater and runoff from the surrounding, primarily urban landscape. Previous RMP monitoring of wastewater influent and effluent, consisting of 24-hour composite samples collected from eight wastewater treatment facilities in the Bay Area in September 2015, detected imidacloprid in 100% of samples at levels up to 310 ng/L. Independent surveys in both northern and southern California urban areas confirm that imidacloprid is a commonly detected insecticide in urban runoff. For example, a San Francisco Bay Area study in Fairfield and Suisun City detected imidacloprid at up to 1,462 ng/L in urban creek waters. However, these concentrations diminished to below detection limits in downstream samples as creek waters mixed with brackish waters from the Bay. While Bay Area agricultural runoff has not been well-characterized with respect to imidacloprid, this pathway may also be of potential interest. A hydrodynamic dilution spreadsheet model was applied as an additional screening tool to explore predicted spatial patterns and temporal trends in imidacloprid concentrations in Bay subembayments. Model inputs were based on available data on concentrations in wastewater effluent and runoff. The model predicted that Lower South Bay levels of imidacloprid would be higher than in other subembayments. The Lower South Bay was also the only subembayment where imidacloprid concentrations were consistently predicted to be higher than method detection limits. The model indicated that wastewater was a dominant pathway for imidacloprid. However, stormwater discharges during the wet season could potentially lead to higher levels in the Bay, suggesting that dry season monitoring may not fully capture maximum concentrations. The results of this simplified dilution model are based on limited input data and do not include all relevant processes and removal mechanisms; they should be interpreted with caution and best viewed as a first step toward quantifiable prediction of open Bay concentrations. Open Bay and margins monitoring of imidacloprid revealed that detected concentrations in Lower South Bay were comparable to or greater than protective US and European Union thresholds that range from 4.8 to 10 ng/L. These observations, in combination with widespread and increasing use of this pesticide in urban settings, indicate that this contaminant should be classified as a Moderate Concern in the RMP tiered risk-based framework for contaminants of emerging concern. Other neonicotinoid pesticides and degradates should be classified as Possible Concern, given their more limited availability in urban use pesticide products, as well as additional uncertainties, particularly the lack of chronic toxicity data and potential for cumulative impacts to wildlife. Additional monitoring is not recommended at this time, due to existing monitoring in urban streams conducted primarily by the California Department of Pesticide Regulation (CDPR). In the future, it may be appropriate for the RMP to explore opportunities for wet season monitoring in Bay water, or in urban runoff. Considering the low toxicity thresholds of these compounds (i.e., in the low ng/L range), analytical methods employed should be improved to provide method detection limits well below toxicity thresholds.

New Life for Eroding Shorelines: Beach and Marsh Edge Change in the San Francisco Estuary

San Francisco Estuary Institute (SFEI) | April 1st, 2020

Wind, waves, storms, and changing water levels have reshaped shorelines for millennia and continue to do so today. The current shape of the San Francisco (SF) Estuary sho

Wind, waves, storms, and changing water levels have reshaped shorelines for millennia and continue to do so today. The current shape of the San Francisco (SF) Estuary shoreline is relatively new; 15,000 years ago, the California shoreline was west of the Farallon Islands and 140 meters below its current level (Cohen and Laws 1992, Malamud-Roam et al. 2007). By approximately 6,000 years ago (the end of the last glacial epoch), the sea had risen to nearly its present level and filled what is now San Francisco Bay, allowing marshes to form and maintain themselves (Atwater 1979). More recently, humans have changed the shape of the shoreline. During the 1850s, many marshes expanded extensively due to increased sediment supply from hydraulic mining in the Sierra Nevada (Gilbert 1917, Goals Project 1999). Diking, dredging, and filling of marshes for agricultural and urban development began in the late 19th century and continued through the first half of the 20th century.  Today, humans continue to reshape the shoreline through continued diking, dredging and filling as well as restoration projects, urbanization of watersheds, ferry wakes, and many other means. The most wide-ranging impact of human activity on the shape of shorelines is global climate change caused by greenhouse gas emissions, which is accelerating the rate of sea level rise worldwide (OPC 2018). Sea level rise is likely to cause much more dramatic changes in the shape of shorelines than have been seen in recent centuries. The magnitude and pace of change will depend on the rate of sea level rise, existing shoreline conditions, and the ability of shorelines to adapt. 

New San Francisco Bay Contaminants Emerge

San Francisco Estuary Institute (SFEI) | July 2nd, 2020

 In 2016, the RMP launched a novel investigation to detect new or unexpected contaminants in Bay waters, as well as treated sewage (or wastewater) discharged to the Bay.

 In 2016, the RMP launched a novel investigation to detect new or unexpected contaminants in Bay waters, as well as treated sewage (or wastewater) discharged to the Bay. This study used non-targeted analysis, a powerful tool that provides a broad, open-ended view of thousands of synthetic and naturally-derived chemicals simultaneously. We identified hundreds of contaminants, and the results have opened our eyes to urban stormwater runoff as an important pathway for emerging contaminants to enter the Bay. 

North American diadromous fishes: Drivers of decline and potential for recovery in the Anthropocene

American Association for the Advancement of Science (AAAS) | January 28th, 2022

Diadromous fishes migrate between freshwater and marine habitats to complete their life cycle, a complexity that makes them vulnerable to the adverse effects of current

Diadromous fishes migrate between freshwater and marine habitats to complete their life cycle, a complexity that makes them vulnerable to the adverse effects of current and past human activities on land and in the oceans. Many North American species are critically endangered, and entire populations have been lost. Major factors driving declines include overfishing, pollution, water withdrawals, aquaculture, non-native species, habitat degradation, over-zealous application of hatcheries designed to mitigate effects of other factors, and effects of climate change. Perhaps, the most broadly tractable and effective factors affecting diadromous fishes are removals of the dams that prevent or hinder their migrations, alter their environment, and often favor non-native biotic communities. Future survival of many diadromous fish populations may depend on this.

North Bay Mercury Biosentinel Project 2016 - 2017

San Francisco Estuary Institute (SFEI) | March 1st, 2018

Concentrations of methylmercury throughout San Francisco Bay are high enough to warrant concern for the health of humans and wildlife. Large-scale tidal wetland restorat

Concentrations of methylmercury throughout San Francisco Bay are high enough to warrant concern for the health of humans and wildlife. Large-scale tidal wetland restoration is currently being implemented as a means of increasing populations of wildlife species of concern. There is concern that these restoration activities may lead to increased concentrations of methylmercury in the estuarine food web and exacerbate the existing methylmercury problem.

North Bay Selenium Monitoring Design

San Francisco Estuary Institute (SFEI) | December 3rd, 2018

The San Francisco Bay Regional Water Quality Control Board developed a Total Maximum Daily Load (TMDL) and implementation plan for selenium in North San Francisco Bay (N

The San Francisco Bay Regional Water Quality Control Board developed a Total Maximum Daily Load (TMDL) and implementation plan for selenium in North San Francisco Bay (NSFB). The TMDL is based on attainment of water column and fish tissue target concentrations protective of human health, aquatic life, and wildlife, and was approved by the U.S. Environmental Protection Agency (USEPA) in August 2016. The USEPA also published proposed aquatic life and aquatic-dependent wildlife criteria for selenium in the Bay and Delta in 2016. Subsequently, the San Francisco Water Board reached out to the Selenium Workgroup of the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) to consider the development and implementation of a robust selenium monitoring plan for the North Bay. A primary goal is to identify leading indicators of change to allow prompt management response to signs of increasing risk of impairment.