Groundwater salinity mapping using geophysical log analysis within the Fruitvale and Rosedale Ranch oil fields, Kern County, California, USA

Hydrogeology Journal (Springer) | September 26th, 2018

A method is presented for deriving a volume model of groundwater total dissolved solids (TDS) from borehole geophysical and aqueous geochemical measurements. Whil

A method is presented for deriving a volume model of groundwater total dissolved solids (TDS) from borehole geophysical and aqueous geochemical measurements. While previous TDS mapping techniques have proved useful in the hydrogeologic setting in which they were developed, they may yield poor results in settings with lithological heterogeneity, complex water chemistry, or limited data. Problems arise because of assumed values for empirical constants in Archie’s Equation, unrealistic porosity and temperature gradients, or bicarbonate-rich groundwater. These issues become critical in complex geologic settings such as the San Joaquin Valley of California, USA. To address this, a method to map TDS in three dimensions is applied to the Fruitvale and Rosedale Ranch oil fields near Bakersfield, California. Borehole resistivity, porosity, and temperature data are used to derive TDS using Archie’s Equation, and are then kriged to interpolate TDS. Archie’s a and m (tortuosity factor and cementation exponent, respectively) are found by comparing model predictions, after kriging, to TDS measurements, and minimizing the differences via mathematical optimization. Contributions of abundant bicarbonate ions to TDS were corrected using an empirical model. This work was motivated by federal and state law requirements to monitor and protect underground sources of drinking water. Modeling shows the legally significant boundary of 10,000 ppm TDS is at ~1,067 m below sea level in Rosedale Ranch, and deepens into Fruitvale to ~1,341 m. Mapping groundwater TDS at this resolution reveals that TDS is primarily controlled by depth, recharge, stratigraphy, and in some places, by faulting and facies changes.

Human viral nucleic acids concentrations in wastewater solids from Central and Coastal California USA

Nature Portfolio (Springer Nature) | June 22nd, 2023

Layperson's Guide to California Wastewater*

Water Education Foundation | December 12th, 2013

This guide, part of an ongoing series by the Water Education Foundation, provides an overview of basic background information on California laws and regulations, wastewat

This guide, part of an ongoing series by the Water Education Foundation, provides an overview of basic background information on California laws and regulations, wastewater collection and treatment processes, history, current challenges, and case studies. Related issues are discussed in the Layperson’s Guide to Water Recycling.  *Abridged version; unabridged version for sale via the Foundation.

Longitudinal metatranscriptomic sequencing of Southern California wastewater representing 16 million people from August 2020–21 reveals widespread transcription of antibiotic resistance genes

Water Research (Elsevier) | November 22nd, 2022

Municipal wastewater provides a representative sample of human fecal waste across a catchment area and contains a wide diversity of microbes. Sequencing wastewater sample

Municipal wastewater provides a representative sample of human fecal waste across a catchment area and contains a wide diversity of microbes. Sequencing wastewater samples provides information about human-associated and medically important microbial populations, and may be useful to assay disease prevalence and antimicrobial resistance (AMR). Here, we present a study in which we used untargeted metatranscriptomic sequencing on RNA extracted from 275 sewage influent samples obtained from eight wastewater treatment plants (WTPs) representing approximately 16 million people in Southern California between August 2020 – August 2021. We characterized bacterial and viral transcripts, assessed metabolic pathway activity, and identified over 2,000 AMR genes/variants across all samples. Because we did not deplete ribosomal RNA, we have a unique window into AMR carried as ribosomal mutants. We show that AMR diversity varied between WTPs (as measured through PERMANOVA, P < 0.001) and that the relative abundance of many individual AMR genes/variants increased over time (as measured with MaAsLin2, Padj < 0.05). Similarly, we detected transcripts mapping to human pathogenic bacteria and viruses suggesting RNA sequencing is a powerful tool for wastewater-based epidemiology and that there are geographical signatures to microbial transcription. We captured the transcription of gene pathways common to bacterial cell processes, including central carbon metabolism, nucleotide synthesis/salvage, and amino acid biosynthesis. We also posit that due to the ubiquity of many viruses and bacteria in wastewater, new biological targets for microbial water quality assessment can be developed. To the best of our knowledge, our study provides the most complete longitudinal metatranscriptomic analysis of a large population's wastewater to date and demonstrates our ability to monitor the presence and activity of microbes in complex samples. By sequencing RNA, we can track the relative abundance of expressed AMR genes/variants and metabolic pathways, increasing our understanding of AMR activity across large human populations and sewer sheds.

Mainstreaming Potable Water Reuse in the United States: Strategies for Leveling the Playing Field

U.S. Environmental Protection Agency (EPA) | April 18th, 2018

The practice of potable water reuse has evolved in important ways in the United States over the past 50 years, especially during the last 25 years. Prior to the 1990s, m

The practice of potable water reuse has evolved in important ways in the United States over the past 50 years, especially during the last 25 years. Prior to the 1990s, many cities and public health regulators recognized that municipal wastewater effluent accounted for a significant fraction of the surface water entering their drinking water treatment plants. Wastewater utilities generally addressed this situation by treating and disinfecting effluent consistent with Clean Water Act permitting requirements and, where feasible, minimizing the fraction of wastewater in drinking water intakes. Because of concerns associated with the presence of wastewater and contaminants from other sources (e.g., industrial pollution, agricultural runoff), some cities began to upgrade drinking water treatment plants by installing advanced treatment technologies to provide enhanced safeguards for public health protection. As water availability and water quality issues became more prevalent in rapidly growing areas, water managers soon began to explicitly consider the use of wastewater effluent to augment water supplies.

Managing Wastewater in a Changing Climate

Public Policy Institute of California (PPIC) | April 15th, 2019

California’s wastewater sector, which plays a crucial role in protecting publichealth and the environment, is at a turning point. Water supply and demand condit

California’s wastewater sector, which plays a crucial role in protecting publichealth and the environment, is at a turning point. Water supply and demand conditions are being affected by population growth, technology and policy changes, and drought. Climate change will bring new challenges. Wastewater agencies are tasked with reliably removing pollutants from water discarded to sewers, even as the quantity and quality of the water they treat declines. Of the multiple climate pressures that are likely to affect wastewater management, drought poses the biggest challenge for the sector. The unusually hot drought of 2012–16 provided a vivid demonstration of conditions that may become more common as the climate warms, and was a wake-up call for wastewater agencies. Many wastewater agencies are pursuing specific changes to their operations, infrastructure, or finances in response to the cascade of challenges they experienced during the latest drought. A PPIC survey of wastewater agencies done as part of this study found a high degree of concern in the sector about adapting to a changing climate. This report recommends policy and management changes to help build resilience in three broad areas: 1) Maintaining water quality in the face of changing water use.Wastewater management is challenged by short-term water conservation during droughts and longer-term reductions in water use from indoor efficiency measures—conditions which are largelybeyond the sector’s control. Reductions in indoor water use can damage infrastructure and reduce the effectiveness of existing treatment processes. Such challenges may grow as severe droughts become more frequent with climate change and as water efficiency increases. Better coordination and information sharing with water suppliers, and sector-wide planning for future droughts, are key to addressing these changes. 2) Making smart recycled water investments. Wastewater agencies produce highly treated water that is increasingly being reused as a water supply. Coordination among wastewater and water supply agencies is essential to respond to the increasing demand for recycled water. Formalized planning for recycled water projects at the regional level will likely lead to more efficient processes and better outcomes. New investments must be responsive to changing water use, climate change, and pending regulations. 3) Balancing conflicting objectives within watersheds. Most wastewater treatment plants discharge treated water into inland watersheds. Adapting to declining water use and meeting increased demand for recycled water may conflict with environmental objectives and the demands of downstream users. Rivers and streams are expected to experience lower flows and higher temperatures, which will heighten threats to aquatic ecosystems. Resources to identify areas most at risk of conflict over the use of treated wastewater are needed, as are tools to evaluate the impacts of water recycling projects on the environment and downstream water users. The state should also analyze its policies to identify tradeoffs and resolve conflicts between its water supply, water quality, and environmental goals. Advancements in engineering and technology can help wastewater agencies adapt to a changing climate―but shifts in policy and planning will facilitate a more efficient and effective path toward building resilience. The latest drought provided a window into the looming challenges facing the wastewater sector. Forging new partnerships and evaluating the full range of climate-related risks will help the sector determine the best adaptations and policy improvements needed to prepare the wastewater sector for a more volatile future.

Microplastic Contamination in San Francisco Bay - Fact Sheet

San Francisco Estuary Institute (SFEI) | November 2nd, 2015

Microplastic contamination in the San Francisco Bay, California, USA

Marine Pollution Bulletin (Elsevier) | August 15th, 2015

Despite widespread detection of microplastic pollution in marine environments, data describing microplastic abundance in urban estuaries and microplastic discharge via tr

Despite widespread detection of microplastic pollution in marine environments, data describing microplastic abundance in urban estuaries and microplastic discharge via treated municipal wastewater are limited. This study presents information on abundance, distribution, and composition of microplastic at nine sites in San Francisco Bay, California, USA. Also presented are characterizations of microplastic in final effluent from eight wastewater treatment plants, employing varying treatment technologies, that discharge to the Bay. With an average microplastic abundance of 700,000 particles/km2, Bay surface water appears to have higher microplastic levels than other urban waterbodies sampled in North America. Moreover, treated wastewater from facilities that discharge into the Bay contains considerable microplastic contamination. Facilities employing tertiary filtration did not show lower levels of contamination than those using secondary treatment. As textile-derived fibers were more abundant in wastewater, higher levels of fragments in surface water suggest additional pathways of microplastic pollution, such as stormwaterrunoff.

Microplastic pollution is widely detected in US municipal wastewater treatment plant effluent

Environmental Pollution (Elsevier) | August 27th, 2016

Municipal wastewater effluent has been proposed as one pathway for microplastics to enter the aquatic environment. Here we present a broad study of municipal wastewater t

Municipal wastewater effluent has been proposed as one pathway for microplastics to enter the aquatic environment. Here we present a broad study of municipal wastewater treatment plant effluent as a pathway for microplastic pollution to enter receiving waters. A total of 90 samples were analyzed from 17 different facilities across the United States. Averaging all facilities and sampling dates, 0.05 ± 0.024 microparticles were found per liter of effluent. Though a small value on a per liter basis, even minor municipal wastewater treatment facilities process millions of liters of wastewater each day, yielding daily discharges that ranged from ∼50,000 up to nearly 15 million particles. Averaging across the 17 facilities tested, our results indicate that wastewater treatment facilities are releasing over 4 million microparticles per facility per day. Fibers and fragments were found to be the most common type of particle within the effluent; however, some fibers may be derived from non-plastic sources. Considerable inter- and intra-facility variation in discharge concentrations, as well as the relative proportions of particle types, was observed. Statistical analysis suggested facilities serving larger populations discharged more particles. Results did not suggest tertiary filtration treatments were an effective means of reducing discharge. Assuming that fragments and pellets found in the effluent arise from the ‘microbeads’ found in many cosmetics and personal care products, it is estimated that between 3 and 23 billion (with an average of 13 billion) of these microplastic particles are being released into US waterways every day via municipal wastewater. This estimate can be used to evaluate the contribution of microbeads to microplastic pollution relative to other sources (e.g., plastic litter and debris) and pathways (e.g., stormwater) of discharge.

Near-Field Receiving-Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California

U.S. Geological Survey (USGS) | November 6th, 2019

Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate co

Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2018 to December 2018. These append to long-term datasets extending back to 1974. A major focus of the report is an integrated description of the 2018 data within the context of the longer, multi-decadal dataset. This dataset supports the City of Palo Alto’s Near-Field Receiving-Water Monitoring Program, initiated in 1994. Significant reductions in silver and copper concentrations in both sediment and M. petalum occurred at the site in the 1980s following the implementation by PARWQCP of advanced wastewater treatment and source control measures. Since the 1990s, concentrations of these elements appear to have stabilized at concentrations somewhat above (silver [Ag]) or near (copper [Cu]) regional background concentrations. Data for other metals, including chromium (Cr), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn), have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2018, concentrations of silver and copper in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported previously. Seasonal patterns for other elements, including Cr, Ni, Zn, Hg, and Se, were generally similar in timing and magnitude as those for Ag and Cu. This record suggests that legacy contamination and regional-scale factors now largely control sedimentary and bioavailable concentrations of silver and copper, as well as other elements of regulatory interest, at the Palo Alto site. Analyses of the benthic community structure of a mudflat in south San Francisco Bay over a 40-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of M. petalum shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissues of this organism. Reproductive activity is presently stable (2018), with almost all animals initiating reproduction in the fall and spawning the following spring. The entire infaunal community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that indicates a more stable community that is subjected to fewer stressors. In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes have shown a continual decline in dominance coincident with the decline in metals; both species had short-lived rebounds in abundance in 2008, 2009, and 2010 and showed signs of increasing abundance in 2018. Heteromastus filiformis (a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying its eggs on or in the sediment) showed a concurrent increase in dominance and, in the last several years before 2008, showed a stable population. H. filiformis abundance increased slightly in 2011–2012 and returned to pre-2011 numbers in 2018. An unidentified disturbance occurred on the mudflat in early 2008 that resulted in the loss of the benthic animals, except for deep-dwelling animals like M. petalum. However, within two months of this event, animals returned to the mudflat. The resilience of the community suggested that the disturbance was not caused by a persistent toxin or anoxia. The reproductive mode of most species that were present in 2018 was indicative of species that were available either as pelagic larvae or as mobile adults. Although oviparous species were lower in number in this group, the authors hypothesize that these species will return slowly as more species move back into the area. The use of functional ecology was highlighted in the 2018 benthic community data, which showed that the animals that have now returned to the mudflat are those that can respond successfully to a physical, nontoxic disturbance. Today, community data show a mix of species that consume the sediment, or filter feed, have pelagic larvae that must survive landing on the sediment, and those that brood their young. USGS scientists view the 2008 disturbance event as a response by the infaunal community to an episodic natural stressor (possibly sediment accretion or a pulse of freshwater), in contrast to the long-term recovery from metal contamination. We will compare this recovery to the long-term recovery observed after the 1970s when the decline in sediment pollutants was the dominating factor.