San Francisco Bay

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 and Emerging Technologies for Sustainable Fisheries: A Comprehensive Landscape Analysis

Environmental Defense Fund (EDF) | April 1st, 2021

The oceans are at an inflection point. The excesses of the 20th century — over-exploitation of most of our accessible biological resources, over-pollution by plastics a

The oceans are at an inflection point. The excesses of the 20th century — over-exploitation of most of our accessible biological resources, over-pollution by plastics and other chemicals, over-crowding of coastal and marine space by unorganized and competing interests and over-capitalization of extractive industries — are being tempered by a rapidly growing realization that these excesses are having very real consequences, not just for marine life and ocean ecosystems, but for the food security and nutrition of the world’s population, the livelihoods of the communities that depend on the ocean and the very future of humanity itself. 

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. 

New streams and springs after the 2014 Mw6.0 South Napa earthquake

Nature Portfolio (Springer Nature) | July 9th, 2015

Many streams and springs, which were dry or nearly dry before the 2014 Mw6.0 South Napa earthquake, started to flow after the earthquake. A United States Geologic

Many streams and springs, which were dry or nearly dry before the 2014 Mw6.0 South Napa earthquake, started to flow after the earthquake. A United States Geological Survey stream gauge also registered a coseismic increase in discharge. Public interest was heightened by a state of extreme drought in California. Since the new flows were not contaminated by pre-existing surface water, their composition allowed unambiguous identification of their origin. Following the earthquake we repeatedly surveyed the new flows, collecting data to test hypotheses about their origin. We show that the new flows originated from groundwater in nearby mountains released by the earthquake. The estimated total amount of new water is ∼106 m3, about 1/40 of the annual water use in the Napa–Sonoma area. Our model also makes a testable prediction of a post-seismic decrease of seismic velocity in the shallow crust of the affected region.

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.

North Delta Water Management Program

California Department of Water Resources (DWR) | March 1st, 1988

Water management issues surrounding the Sacramento-San Joaquin Delta continue to challenge water resource planners in California. Many agree there are problems and urge

Water management issues surrounding the Sacramento-San Joaquin Delta continue to challenge water resource planners in California. Many agree there are problems and urge that they be corrected, but a consensus on how best to solve them has not yet been reached. Problems include frequent flooding due to unstable levees and constricted channels, flow patterns that are unfavorable for fish and water quality, and water level and circulation patterns that hinder irrigation. During the last several years, various water resources problems have been corrected through application of the public environmental documentation and regulatory permit process. This process has also shown the importance of Federal permit regulations in governing projects in the Delta estuary. To facilitate planning, the estuary has been divided into three study areas for evaluation of problems and needs unique to each area -- North, South, and West. This report discusses concepts for a North Delta Water Management Program. The long-term planning and environmental documentation process will includeother reports and will take about three years to complete. Planning flexibility afforded by the environmental documentation and regulatory permit process is expected to allow many of the concerns surrounding Delta water management to be resolved.