PROGRAM HIGHLIGHTS
Uncovering Pollutant Sources for a Healthier Monterey Bay
Identifying water quality stressors through collaborative regional monitoring and scientific studies

The CCLEAN program has uncovered critical insights into the sources and impacts of pollutants in Monterey Bay, providing a clearer understanding of the region’s environmental health. By identifying major pollutant contributors, such as rivers, and assessing the effectiveness of wastewater management, CCLEAN has been instrumental in guiding targeted interventions and regulatory actions. These efforts have led to improved water quality, reduced contamination risks, and enhanced protection for the bay’s ecosystems. The data-driven approach of CCLEAN not only helps protect the natural beauty and biodiversity of Monterey Bay but also supports informed decision-making, ensuring a healthier marine environment for both wildlife and human communities.
Key Findings from CCLEAN Data

Rivers as Major Pollutant Sources
Rivers have been found to discharge much higher loads of most pollutants to the ocean compared to wastewater discharges, indicating the need for targeted management efforts in these areas. The 2022 CCLEAN annual report highlights pollutant trends and loads in Pajaro River that indicate DDTs have not declined over time, but exhibit an exponential relationship with annual rainfall, with regular exceedances of water quality objectives in nearshore waters.

Exceedances of Water Quality Objectives
Ocean water in Monterey Bay has exceeded water quality objectives for polychlorinated biphenyls (PCBs), DDTs, Chlordanes, Dieldrin, and Toxaphene. Notably, PCBs have exceeded objectives in at least one sample every year since 2001, highlighting a persistent issue in the bay’s water quality. The 2022 CCLEAN annual report documents the current status of exceedances in the California Ocean Plan and other pertinent guidelines.

Pesticide Contamination in Mussels
Concentrations of the pesticide Dieldrin in mussels along the northern shore of Monterey Bay have exceeded human health alert levels, posing a potential risk to both wildlife and humans. Pesticide concentrations in mussels have generally declined over time, although large increases occur following extreme rainfall events, providing a direct link between storm runoff, river discharges and effects on biological resources. The 2016 and 2017 CCLEAN annual reports identified several of these large increases following high runoff events.

Bacterial Water Quality Standards
There have been no sustained exceedances of bacterial water quality objectives in the waters surrounding municipal wastewater discharges, indicating effective management in these areas. The 2019 CCLEAN Annual Report includes a comprehensive review of bacteria data collected by the Program and comparisons to water quality standards.
CCLEAN monitoring has included nutrients and emerging contaminants as two indicators of potential climate-mediated effects. Data on these constituents entering the ocean have informed changes in impairment of the Bay. Current and future climate change effects—such as more frequent wildfires, storm events, and droughts—exacerbate challenges to wastewater management and access to water resources to sustain beneficial uses of the Monterey Bay region.
Prevalence of Emerging Contaminants
Addition of emerging contaminants to routine monitoring
Inputs of Nutrients to Monterey Bay
Nutrient monitoring in nearshore Monterey Bay, rivers, and wastewater sources
Key Findings from CCLEAN Special Studies
CCLEAN commissioned the University of California Davis Marine Pollution Studies Laboratory at Granite Canyon to perform bioassays using fathead minnows (Pimephales promelas) to test for endocrine disruption activity in each participant’s wastewater effluent at estimated effluent dilutions provided by each respective outfall diffuser. Observation endpoints included fecundity and fertilization success, behavior and appearance, nuptial tubercle scores, weight, gonadosomatic index, dorsal fat pad index, embryo hatch success, and plasma vitellogenin. The results suggested that there was likely no impact on fathead minnow reproduction in any of the treatment plant effluents at the concentrations tested. While some parameters measured in the test are possible indicators of endocrine disruption due to effluent exposure, only the Santa Cruz treatment had significantly lower fecundity, the primary endpoint indicating reproductive impairment. Based on the fact that the pre-exposure egg production in the Santa Cruz aquaria did not significantly differ from the effluent exposure egg production, it was concluded that reduced egg production in the Santa Cruz effluent was not caused by endocrine disruption. The Endocrine Disruption Study Report can be found in the 2010 CCLEAN annual report.
In cooperation with California Department of Fish and Wildlife, CCLEAN was awarded a grant from the California State Water Board to perform a comprehensive study of persistent organic pollutants if archived tissues from 227 freshly dead wild southern sea otters (Enhydra lutris nereis) stranding between 2000 and 2005 along the California coast between San Francisco and Ventura. For each animal a complete necropsy was performed by the California Department of Fish and Game, providing detailed data on each otter’s age class, sex and nutritional condition, as well as data on the primary and contributing causes of death. Consideration of these data, along with each otter’s stranding location and liver POP concentrations permitted detailed statistical analyses of the spatial, environmental and demographic relationships with the detection of high POP concentrations in sea otters, as well as relationships between elevated liver POP concentrations and major causes of sea otter death. The Southern Sea Otter Study Report can be found in the CCLEAN Library.
In cooperation with the University of California, Davis and the California Department of Fish and Wildlife, CCLEAN was awarded a grant from the California State Water Board to use both laboratory and field approaches to investigate issues related to water quality monitoring and mitigation of fecal pathogen pollution along the central California coast. Our specific objectives were to 1) evaluate water quality monitoring approaches by characterizing the relationships between FIB and enteric pathogen detection in a broad range of freshwater and marine surface waters along the central coast, 2) consider the relative importance of fecal pathogen loading from different sources, 3) evaluate whether filter-feeding estuarine or marine invertebrates (mussels) may be better indicators of water quality than direct water testing, 4) evaluate microbial source tracking techniques to distinguish between human and animal sources of fecal pollution, 5) characterize patterns of fecal pathogen shedding among terrestrial and marine animals, and 6) evaluate wetlands as a possible Best Management Practice (BMP) to mitigate impairments and improve surface water quality with respect to fecal pathogen pollution. The Fecal Pathogen Study Report can be found in the CCLEAN Library.
As part of CCLEAN’s routine measurements, nutrient and pathogen data are collected from several streams in the Monterey Bay region. CCLEAN compared SeaWIFS chlorophyll (n=11, 4 sites, N=44) and normalized water leaving radiance at 555 nm (nLw555; n=4, 4 sites, N=16) for reference and “impact” stations near Scott Creek and Pajaro River. Using paired t-tests, CCLEAN found that Pajaro River was significantly different from its reference site, and from Scott Creek. Based on this initial analysis, we proposed to provide a more detailed spatial correlation between river flow and SeaWiFS data. A study was performed to determine whether elevated polychlorinated biphenyl (PCB) concentrations measured in the Monterey Bay waters by CCLEAN could have come from nearby wastewater or river discharges. The River Discharges Study Report can be found in the CCLEAN Library.
Each CCLEAN participating agency was required to implement monitoring of influent, effluent and biosolids for a specified list of PFAS analytes. The collection and analysis of samples were performed according to stringent State of California and Department of Defense protocols that minimized sample contamination due to clothing and sample collection equipment. The program was performed under the auspices of CCLEAN so that economies of scale could be achieved in cleaning sample containers and reporting results. All data were submitted directly to the State’s GeoTracker database.
In response to regulatory agency initiatives to improve understanding of the types and quantities of microplastic particles being discharged into Monterey Bay by municipal wastewater agencies, CCLEAN added microplastics as an emerging contaminant to be measured under the program in 2020. Although there are currently no restrictions for daily loads of microplastics being discharged into Monterey Bay in wastewater, the information provided by this microplastics pilot monitoring program will enable resource managers to assess whether estimated loads from wastewater and rivers are sufficient to warrant further measurements or regulatory actions.
In 2021, the sum of daily loads of anthropogenic microparticles from five effluent sources was almost two times greater than the sum of daily loads from three river sources discharging into Monterey Bay National Marine Sanctuary. Fibers, both plastic and natural-based, were the dominant microparticle morphology type in all effluent and river samples collected in 2021. Fragments were the second most abundant microparticle morphology type for all effluent and river sites, apart from Monterey One Water, where films were the second most abundant. In dry season of 2021, fiber, fragment, and fiber bundle microparticle types were present in Santa Cruz City and County influent sources. The City of Santa Cruz effluent, however, only contained fiber microparticles. Estimated daily loads of anthropogenic microparticles also decreased by about 99.95% between the combined Santa Cruz City and County influent and Santa Cruz effluent stages, suggesting that the majority of anthropogenic microparticles may have been removed, or settled in the storage tanks, during wastewater treatment processes before being discharged as effluent. The Microplastics Study Report is featured in the 2021 CCLEAN annual report.