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  • POTWs embark on study documenting antibiotic-resistant bacteria, genes in effluent

    July 31, 2017:

    SCCWRP and its four wastewater treatment member agencies have initiated a year-long study examining whether viable antibiotic-resistant bacteria – and the genes that code for antibiotic resistance – are being discharged into the environment following the wastewater treatment process.

    The study, which began in June, will track whether viable bacteria and genetic material are surviving treatment at 10 POTW facilities across Southern California, including an international plant at the U.S.-Mexico border. Influent and effluent samples are being collected quarterly at each wastewater treatment plant.

    The study’s goal is to develop a baseline understanding of how prevalent antibiotic resistance genes are in wastewater effluent at Southern California’s treatment facilities. If these genes are surviving the treatment processes that destroy most bacterial cells, this genetic material could be traveling via treated effluent into aquatic systems, where potentially pathogenic bacteria in the environment could be taking up the antibiotic resistance genes. In this way, antibiotic resistance could be conferred to bacterial strains that make humans sick – a phenomenon that research has shown can lead to multidrug-resistant “superbugs."

    The study also will examine whether differences in wastewater treatment regimens and effluent discharge practices across Southern California affect the viability of antibiotic-resistant bacteria and genes. This information will be particularly timely given that treated effluent in Southern California increasingly is being reused for water recycling projects, including direct groundwater injection.

    During the study, researchers will screen for three classes of bacterial pathogens resistant to antibiotics: vancomycin-resistant Enterococcus (VRE), methicillin-resistant Staphylococcus aureus (MRSA), and carbapenem-resistant Enterobacteriaciae (CRE). Carbapenems are often the antibiotic of last resort against many life-threatening infections.

    Researchers will then use DNA-based methods to identify the antibiotic-resistant bacterial species and the antibiotic resistance genes in the influent and effluent. To determine which genes to target during this molecular analysis, researchers are partnering with the Argonne National Laboratory at the University of Chicago, which has curated a large database of known gene sequences coding for antibiotic resistance. Argonne National Laboratory has conducted similar antibiotic resistance work in the Chicago River.

    Study participants have spent the past few months optimizing lab analysis techniques to ensure they can generate high-quality, comparable results across facilities participating in the study. The majority of the POTW facilities are scheduled to finish their first round of sampling by September.

    For more information, contact Dr. John Griffith.


    Bacterial conjugation, shown in this image, is one of the ways that bacterial cells can
    swap genetic material, potentially conferring antibiotic resistance to one another.
    SCCWRP and its wastewater treatment member agencies are tracking whether
    the genetic material that codes for antibiotic resistance is being discharged into
    the environment following the wastewater treatment process.

  • Bioassays show promise for CEC screening in SMC study

    July 31, 2017:

    SCCWRP and its partners have demonstrated in a proof-of-concept study that commercially available bioanalytical tools have the potential to cost-effectively screen Southern California waterways for the presence of bioactive contaminants of emerging concern (CECs).

    The two-year study, completed in June in partnership with the Southern California Stormwater Monitoring Coalition (SMC), examined the relationship between the results of the high-throughput cell assays and the results of a whole-animal screening test. In all, 31 stream sites across Southern California were sampled over a two-year period.

    The study found that one of the cell screening assays – the aryl hydrocarbon receptor assay – detected low to moderate levels of a group of bioactive contaminants known as dioxin-like chemicals across both urban and agricultural sites. A subsequent whole-animal screening test showed that these levels of bioactivity were not associated with cardiac malformations during early zebrafish embryo development.

    These findings are significant because SCCWRP and other experts have proposed using bioanalytical tools as a cost-efficient first line of defense for screening California waterways for bioactive contaminants, an approach that has the potential to reduce the frequency of whole-animal testing, which is more expensive.

    Thus, the study’s finding that cell assays are more sensitive than whole-animal tests is a seminal outcome, as it underscores the potential to use cell assays as an initial screening test, to be followed by whole-animal testing to ascertain whether the bioactive contaminants could be impacting organisms in the environment.

    SCCWRP proposed this multi-tiered approach to CEC screening in 2015, as part of a draft CEC monitoring framework intended to help water-quality managers more effectively narrow down the classes of CECs that pose the greatest potential risks to aquatic ecosystems. Since that time, researchers have launched multiple studies to evaluate the utility of the proposed CEC management strategy for statewide application.

    The outcomes of the SMC zebrafish embryo test are in agreement with previous studies on the toxicity associated with dioxin-like chemicals. When these bioactive contaminants are present at concentrations much higher than those found in the SMC samples, zebrafish embryos begin to experience developmental anomalies. Researchers are still working to link these biological impacts to relevant cell assay screening thresholds.

    The SMC study also explored whether the bioactive contaminants detected during the initial bioanalytical screening step could be correlated in a meaningful way with the level of urbanization of the study sites, as well as with the observed condition of the stream biological communities living at the sites.

    Researchers found that the biological condition of benthic invertebrate communities – as measured by the California Stream Condition Index co-developed by SCCWRP – correlated with the aryl hydrocarbon receptor assay responses. The poorer the biological condition at a given site, the more likely it was to have a relatively high bioassay response, although researchers cautioned that additional linkage studies are needed to confirm whether aryl hydrocarbon receptor-mediated pathways play an influential role in the observed biological degradation.

    The full study has been published by the journal Environmental Science: Processes & Impacts. For more information, contact Dr. Alvina Mehinto.


    A bioanalytical screening tool known as the aryl hydrocarbon receptor assay was used
    to screen water samples collected by the Southern California Stormwater Monitoring
    Coalition for the presence of bioactive contaminants. The assay had a proportionately
    stronger response – depicted above with progressively darker shading – in areas with
    more human activity, which indicates that the assay successfully detected bioactive
    contaminants at levels that correspond to what researchers expected to find, given
    various land-use patterns.

  • SCCWRP-developed CEC monitoring framework highlighted at State Water Board meeting

    June 02, 2017:

    State Water Board members explored multiple approaches being taken to improve CEC monitoring statewide during an informational meeting agenda item in February.

    Some of the presentations they heard at the meeting highlighted an adaptive management strategy developed by SCCWRP to evaluate the risks of CECs in aquatic systems.

    Two Regional Water Quality Control Boards – North Coast and Los Angeles – discussed the pilot studies they’re undertaking with SCCWRP in their respective regions to evaluate the utility of this CEC monitoring strategy.

    Initially unveiled by SCCWRP in 2015, the risk-based adaptive management strategy is intended to provide water-quality managers with an efficient, cost-effective way to zero in on the CECs that pose the greatest potential risks to humans and ecosystems.

    Through the pilot studies, water-quality managers will gain insights into whether the monitoring strategy could be effectively applied to aquatic systems across California, particularly water bodies with significant water-quality impairments.

    During the February 22 informational agenda item, State Water Board staff also briefed board members on the underlying research that SCCWRP and its partners are conducting to refine the scientific tools that are foundational to the strategy. 

    SCCWRP’s CEC monitoring strategy focuses on two emerging technologies that SCCWRP has been working on with collaborators for nearly a decade: 

    » Bioanalytical screening assays, in which engineered cell lines are exposed to water samples so that a potential biological response can be measured

    » Non-targeted chemical analysis, in which chromatography and rapid-scan mass spectrometry are used to separate and identify chemicals in complex mixtures based on physical and chemical properties

    These technologies have the potential to enable water-quality managers to screen a much larger universe of CECs than they can with existing, chemical-specific monitoring methods. Incorporation of these CEC screening tools could streamline existing monitoring workflows and make more efficient use of labor-intensive, time-consuming traditional methods, such as whole-organism toxicity testing and targeted chemical analyses.

    In May, SCCWRP is scheduled to brief regulators and dischargers from the Central Valley and Delta regions on the CEC monitoring strategy during a two-day workshop in Sacramento.

    And later this year, SCCWRP will reassemble an expert advisory panel that will help SCCWRP vet and help shape research to improve CEC monitoring in recycled water. SCCWRP assembled the initial statewide panel in 2009.

    For more information, contact Dr. Keith Maruya

    Next-generation CEC monitoring strategies that SCCWRP is working to test and 
    validate were described by State Water Board staff during a presentation to board
     members exploring the approaches being used to improve CEC monitoring statewide.

  • EPA workshop focuses on science-informed solutions for managing HABs

    June 02, 2017:

    About 150 water-quality managers from across the nation discussed the state of knowledge about harmful algal blooms (HABs) and best-practices solutions and strategies for combatting them during a management-focused workshop in April at SCCWRP.

    The three-day workshop, hosted by the U.S. Environmental Protection Agency and California’s Surface Water Ambient Monitoring Program, provided a forum for lake managers, public health officials, tribal leaders and other water-quality managers to get up to speed on the latest science and to share their in-field experiences with HABs. 

    HAB events trigger production of algal toxins that can impair water quality and threaten the health of humans, wildlife and domestic pets.

    SCCWRP, which was invited by the EPA to co-organize the workshop, will use the feedback provided by meeting attendees to help shape its own HAB research agenda. SCCWRP already co-authored a statewide strategy in 2016 intended to help California water-quality managers build capacity for HAB monitoring and assessment work and to coordinate management responses.

    In particular, meeting attendees – who hailed from California, Nevada, Arizona, Washington and the Pacific Islands, including Hawaii – underscored the need for more research on freshwater HABs. 

    Furthermore, lake managers discussed their experiences relying on “Band-Aid” approaches – such as algicides and nutrient binders – to curb HAB events. The national HAB experts who presented at the workshop, including SCCWRP’s Dr. Meredith Howard, emphasized that these temporary solutions should only be one component of a multi-pronged HAB management strategy.

    To effectively manage HABs over the long term, experts at the workshop recommended site-specific investigations to understand the environmental factors driving blooms and toxin production, including nutrient inputs, hydrology and water residence time, salinity and temperature.  By understanding the primary drivers of HAB events within a waterbody, water-quality managers can develop targeted, customized watershed management plans, as well as strategies for appropriately utilizing short-term waterbody treatments.

    The workshop featured on-the-ground testimonials from water-quality managers from as far away as Ohio, Massachusetts and South Carolina who have been successful in managing HAB events. They offered practical advice for how to develop a HAB monitoring program grounded in the latest science.

    About 100 people attended the workshop in person, plus about 50 more via webinar.

    For more information, contact Dr. Meredith Howard.

    Pinto Lake in Santa Cruz County, tainted a murky greenish color by toxic cyanobacteria, 
    is an example of the type of HAB events that water-quality managers are working to curb 
    through more research and ongoing monitoring. HAB management was the focus of a
     three-day EPA workshop at SCCWRP. 

  • SCCWRP research featured at S.D. Regional Board workshop on monitoring technologies

    June 01, 2017: Next-generation environmental monitoring technologies being developed by SCCWRP and its research partners were featured at an April workshop hosted by the San Diego Regional Water Quality Control Board that focused on how newer technologies could improve the quality and speed of routine data collection.  

    The technology workshop, titled “Use of Remote Monitoring Technologies to Assist the San Diego Water Board Mission,” was designed to expose Regional Board members to promising, next-generation solutions for environmental monitoring. 

    The April 12 agenda item prominently featured SCCWRP presentations and demonstrations, and covered topics that ranged from unmanned aerial systems to bioanalytical screening tools. The board spent about an hour listening to presentations and engaging in discussion, then took part in demonstrations over a 90-minute lunch break. 

    Four SCCWRP staff attended the meeting to give presentations and lead demonstrations: 

    » Dr. Steve Steinberg provided an overview of how multispectral cameras can be attached to unmanned aerial systems to obtain high-quality imagery and develop topographic models. 

    » Dr. Alvina Mehinto discussed the adaption of commercially available cell bioassays to rapidly screen receiving waters for contaminants of emerging concern (CECs). 

    » Shelly Moore demonstrated the potential of virtual-reality goggles to aid in scenario planning and to visit inaccessible and difficult-to-reach areas. 

    » Paul Smith demonstrated the use of mobile applications for streamlining field data collection, as well as open-access portals for storing and sharing data. Other presentations covered topics for which SCCWRP serves as a research collaborator, including in situ passive sampling devices for measuring contaminants in receiving waters, and a field instrument that can continuously monitor receiving waters for microbial contamination. SCCWRP’s interactions with board members and others during the Regional Board meeting will help the agency refine and expand its research directions going forward. For more information, contact Dr. Steve Steinberg.

    SCCWRP’s Shelly Moore, left, guides Melissa Valdovinos of the San Diego  Regional 
    Water Quality Control Board through a virtual-reality tour of the mouth of the Tijuana
     River during a board meeting in April. During the meeting, SCCWRP delivered a series 
    of presentations and demonstrations for board members on  next-generation monitoring

  • New stream flow targets aid in watershed planning decisions

    June 01, 2017: SCCWRP and its partners have published a comprehensive study outlining how to use a suite of newly developed flow-ecology modeling tools to optimally protect the in-stream biological communities of more than 600 wadeable stream sites across Southern California.

    The three-year study, published in March, is intended to help Southern California watershed managers as they make difficult decisions regarding how to set stream flow targets across a watershed – decisions that can affect everything from reservoir operations to stormwater capture and use strategies.

    The flow-ecology modeling work involved mathematically modeling the hydrological flow patterns that are necessary to sustain healthy, in-stream biological communities for 572 wadeable stream sites across Southern California.

    Watershed managers already have begun using the flow-target data sets, along with associated assessment tools developed during the study, to understand the ecological implications of altering hydrological flow patterns in various watersheds. Study data also are being used to inform development of a statewide assessment framework that will guide watershed managers in setting recommended flow targets for streams statewide.

    The scientific framework that SCCWRP and its partners used to develop the recommended flow targets is known as the Ecological Limits of Hydrologic Alteration (ELOHA). The framework relates flow alterations to stream condition as indicated by benthic macroinvertebrate stream communities. With ELOHA, researchers are able to factor in a wide range of flow conditions (i.e., stormwater flows vs. low flows) and climatic conditions (i.e., wet vs. dry years).

    During the study, researchers identified seven flow metrics identified as having the most influence on biological condition; flow alterations beyond the thresholds proposed by the study were assumed to be associated with declines in in-stream biological condition. Watershed managers can now use the stream flow-target data and assessment tools to evaluate the impacts of proposed flow alterations, as well as prioritize areas for protection. The flow-target data also offer insights into the level of influence that flow patterns have in terms of altering in-stream biological health at a given site, relative to other factors such as contamination and habitat alteration.

    In-stream biological health is one of numerous factors that watershed managers must take into account as they set flow targets for various streams. Watershed managers also are responsible for maintaining flood-control protections, maximizing conservation and reuse, and being responsive to requests to maintain existing flows for ecological purposes.

    The San Diego River watershed served as the first case study evaluating the utility of the new flow-ecology modeling tools. Watershed managers there used the tools to evaluate how proposed changes in reservoir management strategies would impact in-stream biological communities. The managers also examined how the proposed installation of low-impact development (LID) solutions for managing stormwater runoff would impact in-stream biological health.

    For more information, contact Dr. Eric Stein.

    A SCCWRP-led flow-ecology study has generated data on the hydrologic flow
    patterns that are necessary to support healthy, in-stream biological communities
    for hundreds of wadeable stream sites in Southern California. Many of these sites
    don’t presently have optimal flow patterns for in-stream biological communities, as
    shown in the map above, where flow conditions at various sites have been scored
    and assigned a grade of A through D.