National trends in drinking water quality violations

National Academy of Sciences (NAS) | February 27th, 2018

Ensuring safe water supply for communities across the United States is a growing challenge in the face of aging infrastructure, impaired source water, and straine

Ensuring safe water supply for communities across the United States is a growing challenge in the face of aging infrastructure, impaired source water, and strained community finances. In the aftermath of the Flint lead crisis, there is an urgent need to assess the current state of US drinking water. However, no nationwide assessment has yet been conducted on trends in drinking water quality violations across several decades. Efforts to reduce viola- tions are of national concern given that, in 2015, nearly 21 million people relied on community water systems that violated health- based quality standards. In this paper, we evaluate spatial and temporal patterns in health-related violations of the Safe Drinking Water Act using a panel dataset of 17,900 community water systems over the period 1982–2015. We also identify vulnerability factors of communities and water systems through probit regres- sion. Increasing time trends and violation hot spots are detected in several states, particularly in the Southwest region. Repeat viola- tions are prevalent in locations of violation hot spots, indicating that water systems in these regions struggle with recurring issues. In terms of vulnerability factors, we find that violation incidence in rural areas is substantially higher than in urbanized areas. Meanwhile, private ownership and purchased water source are associated with compliance. These findings indicate the types of underperforming systems that might benefit from assistance in achieving consistent compliance. We discuss why certain violations might be clustered in some regions and strategies for improving national drinking water quality.

Nationwide geospatial analysis of county racial and ethnic composition and public drinking water arsenic and uranium

Nature Portfolio (Springer Nature) | December 3rd, 2022

There is no safe level of exposure to inorganic arsenic or uranium, yet recent studies identified sociodemographic and regional inequalities in concentrations of these fr

There is no safe level of exposure to inorganic arsenic or uranium, yet recent studies identified sociodemographic and regional inequalities in concentrations of these frequently detected contaminants in public water systems across the US. We analyze the county-level association between racial/ethnic composition and public water arsenic and uranium concentrations from 2000–2011 using geospatial models. We find that higher proportions of Hispanic/Latino and American Indian/Alaskan Native residents are associated with significantly higher arsenic and uranium concentrations. These associations differ in magnitude and direction across regions; higher proportions of non-Hispanic Black residents are associated with higher arsenic and uranium in regions where concentrations of these contaminants are high. The findings from this nationwide geospatial analysis identifying racial/ethnic inequalities in arsenic and uranium concentrations in public drinking water across the US can advance environmental justice initiatives by informing regulatory action and financial and technical support to protect communities of color.

Natural and Anthropogenic Hexavalent Chromium, Cr(VI), in Groundwater near a Mapped Plume, Hinkley, California

U.S. Geological Survey (USGS) | May 25th, 2023

Related documents in this series: Chapter A: Introduction to Study Area Hydrogeology, Chromium Sources, Site History, and Purpose of Study Chapter B: Survey of Chro

Related documents in this series: Chapter A: Introduction to Study Area Hydrogeology, Chromium Sources, Site History, and Purpose of Study Chapter B: Survey of Chromium and Selected Element Concentrations in Rock, Alluvium, and Core Material Chapter C: Chromium in Minerals and Selected Aquifer Materials Chapter D: Analyses of Regulatory Water-Quality Data Chapter E: Groundwater Chemistry and Hexavalent Chromium Chapter F: Environmental Tracers of Groundwater Source, Age, and Geochemical Evolution Chapter G: Evaluation of Natural and Anthropogenic (Human-Made) Hexavalent Chromium Chapter H: Predevelopment Water Levels, Groundwater Recharge, and Selected Hydrologic Properties of Aquifer Materials, Hinkley and Water Valleys, California Chapter I: Sequestration and Reoxidation of Chromium in Experimental Microcosms Chapter J: Summary and Conclusions

Natural infrastructure in sustaining global urban freshwater ecosystem services

Nature Portfolio (Springer Nature) | October 21st, 2021

Rapid urbanization throughout the globe increases demand for fresh water and the ecosystem services associated with it. This need is conventionally met through the constr

Rapid urbanization throughout the globe increases demand for fresh water and the ecosystem services associated with it. This need is conventionally met through the construction of infrastructure. Natural infrastructure solutions have increased to provide freshwater ecosystem services, but little global research has examined the intricate relationships between built and natural infrastructure for providing freshwater ecosystem services to cities across the globe. Using network analysis, here we examine the interrelationships between built and natural infrastructure in 2,113 watersheds for 317 cities worldwide, focusing on four key freshwater ecosystem services: freshwater provision, sediment regulation, flood mitigation and hydropower production. Our results indicate that protected wetlands contribute to sustaining freshwater provision to cities. Forest cover in protected areas can improve the capacity of large dams in reducing sediment loads and producing hydropower, but cities mainly depend on reduced impervious surfaces and more green spaces within urban areas for flood mitigation. Improved understandings of the role of natural infrastructure in urban water networks must underpin strategic decision-making to sustainably provide freshwater ecosystem services to global cities.

Natural Resources Defense Council v. Kempthorne, Order Granting in Part and Denying in Part Plaintiffs’ Motion for Summary Judgment

United States District Court, Eastern District of California | May 7th, 2007

This case concerns the effect on a threatened species of fish, the Delta smelt (Hypomesus transpacificus) , of the coordinated operation of the federally managed Central

This case concerns the effect on a threatened species of fish, the Delta smelt (Hypomesus transpacificus) , of the coordinated operation of the federally managed Central Valley Project ("CVP") and the State of California's State Water Project *2 ("SWP"), among the world's largest water diversion projects. Both projects divert large volumes of water from the California Bay (Sacramento - San Joaquin) Delta ("Delta") and use the Delta to store water.

Navigability and its Consequences: State Title, Mineral Rights, and the Public Trust Doctrine

Social Science Research Network (SSRN) | June 12th, 2014

“Navigability” and “navigable waters” are two of the most complex terms of art in American law because their meanings vary from context to context. A “navigable

“Navigability” and “navigable waters” are two of the most complex terms of art in American law because their meanings vary from context to context. A “navigable water” for purposes of the federal courts’ admiralty jurisdiction is not precisely the same thing as a “navigable water” for Commerce Clause purposes, and the Commerce Clause definition can be further refined in statute like the federal Clean Water Act. Other important federal law definitions of navigability govern state title to banks and beds of waterways and the scope of the federal navigation servitude. As this article will discuss, these tests overlap considerably, and attempts to distinguish them can cause confusion. State law definitions of “navigability” for state regulatory purposes complicate the multiple valences of “navigable water” even further. This article provides an overview of some of the more important definitions of “navigability” and “navigable waters.” In general, labeling a waterway as “navigable” signals that either the federal government or the public acquires some right to the waterway in question. However, if the waterway also meets the “navigable water” test for state title, complicated legal relationships among the federal government, the relevant state, the general public, and private riparian landowners almost inevitably follow.

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.

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 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 Stone Water District GSA Groundwater Sustainability Plan

New Stone Water District (NSWD) | September 23rd, 2019