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At least 793 records · Page 44Linked to original sources

USGS2018

Long Island South Shore Estuary Reserve Coordinated Water Resources Monitoring Strategy

Executive Summary The Long Island South Shore Estuary Reserve Coordinated Water Resources Monitoring Strategy (CWRMS) provides an overview of the water-quality and ecological monitoring within the Reserve and presents suggestions from stakeholders for future data collection, data management, and coordination among monitoring programs. The South Shore Estuary Reserve, hereafter referred to as the Reserve, is a 173-square-mile network of bays and tributaries shaped by the south shore of Long Island (New York) and the barrier islands that was formed as a result of the last ice age (roughly 18,000 years ago). This overview and coordination document is based on information assembled from a series of meetings, a workshop, and individual correspondences with the CWRMS Project Advisory Committee, which was formed in 2015 to help guide the creation of the document, which reflects the current (2017) status of the Reserve and the need for additional data to address its water-quality issues and ecological health and to respond to a changing climate. The U.S. Geological Survey (USGS), in cooperation with the New York State Department of State Office of Planning, Development and Community Infrastructure and the South Shore Estuary Reserve Office, compiled information and recommendations to help stakeholders efficiently evaluate waters currently being monitored and address areas where necessary data are lacking. Water-quality monitoring in the Reserve is ongoing on the Federal, State, and local levels, and coordination among the various programs administered by the U.S. Environmental Protection Agency; National Oceanic and Atmospheric Administration; USGS; Shinnecock Tribal Nation; New York State; Nassau and Suffolk Counties; the Towns of Hempstead, Oyster Bay, Babylon, Islip, Brookhaven, and Southampton; and local universities and nonprofit organizations is necessary to ensure cooperation and efficient use of limited resources. Proper collection and archival of data are critical to the usability of data and methods—a sample of available repositories for monitoring data are provided in this report. Equally important are quality assurances of data and proper techniques of archival such that water and ecological data are collected and analyzed in a consistent manner, regardless of their sources, and that differences in methodologies are identified that might result in discrepancies in the compiled data. Details on monitoring programs, data gaps that are perceived by stakeholders and researchers in the area, and Project Advisory Committee recommendations are provided in this report to promote discussion and coordination. In most cases, resources to fill data gaps are needed, and the use of citizen science volunteers has been shown to help extend programs and provide insight into previously unaddressed areas of concern. This document, in conjunction with the CWRMS website and interactive mapper, is intended to inform the latest iteration of the Comprehensive Management Plan for the Reserve. Moreover, resource managers can use the CWRMS and mapper to identify areas of potential overlap and initiate conversations with stakeholders about addressing needs for additional monitoring of water quality and ecological health in the bays and tributaries of the Reserve.

New York↗

USGS2014

User's manual for the upper Delaware River riverine environmental flow decision support system (REFDSS), Version 1.1.2

Between 2002 and 2006, the Fort Collins Science Center (FORT) at the U.S. Geological Survey (USGS) conducted field surveys, organized workshops, and performed analysis of habitat for trout and shad in the Upper Delaware River Basin. This work culminated in the development of decision support system software (the Delaware River DSS–DRDSS, Bovee and others, 2007) that works in conjunction with the Delaware River Basin Commission’s reservoir operations model, OASIS, to facilitate comparison of the habitat and water-delivery effects of alternative operating scenarios for the Basin. This original DRDSS application was developed in Microsoft Excel and is available to all interested parties through the FORT web site ( http://www.fort.usgs.gov/Products/Software/DRDSS/ ). Initial user feedback on the original Excel-based DSS highlighted the need for a more user-friendly and powerful interface to effectively deliver the complex data and analyses encapsulated in the DSS. In order to meet this need, the USGS FORT and Northern Appalachian Research Branch (NARB) developed an entirely new graphical user interface (GUI) application. Support for this research was through the DOI WaterSmart program ( http://www.doi.gov/watersmart/html/index.php ) of which the USGS component is the National Water Census ( http://water.usgs.gov/watercensus/WaterSMART.html ). The content and methodology of the new GUI interface emulates those of the original DSS with a few exceptions listed below. Refer to Bovee and others (2007) for the original information. Significant alterations to the original DSS include: • We moved from Excel-based data storage and processing to a more powerful database back end powered by SQLite. The most notable effect of this is that the previous maximum temporal extent of 10 years has been replaced by a dynamic extent that can now cover the entire period of record for which we have data (1928–2000). • We incorporated interactive geographic information system (GIS) visualization and dynamic data processing. Previous habitat maps were generated outside of the DSS in an ad hoc process that the end user could not update or investigate. • The original bathymetric data collected in 2005 at the three main stem reaches was augmented with a higher resolution dataset collected in 2010. This new dataset was collected in order to conduct higher resolution (finer pixel size) two-dimensional (2D) hydrodynamic modeling for evaluating dwarf wedgemussel (DWM, Alasmidonta heterodon ) habitat. • Results charts are now substantially more interactive, dynamic, and accessible, which allows users to more easily focus on their particular topics of interest as well as drill down to the source data used to calculate given results.

Open-File Report↗

USGS2008

Metals fate and transport modelling in streams and watersheds: state of the science and USEPA workshop review

Metals pollution in surface waters from point and non-point sources (NPS) is a widespread problem in the United States and worldwide (Lofts et al. , 2007; USEPA, 2007). In the western United States, metals associated with acid mine drainage (AMD) from hardrock mines in mountainous areas impact aquatic ecosystems and human health (USEPA, 1997a; Caruso and Ward, 1998; Church et al. , 2007). Metals fate and transport modelling in streams and watersheds is sometimes needed for assessment and restoration of surface waters, including mining-impacted streams (Runkel and Kimball, 2002; Caruso, 2003; Velleux et al. , 2006). The Water Quality Analysis Simulation Program (WASP; Wool et al. , 2001), developed by the US Environmental Protection Agency (USEPA), is an example of a model used for such analyses. Other approaches exist and appropriate model selection depends on site characteristics, data availability and modelling objectives. However, there are a wide range of assumptions, input parameters, data requirements and gaps, and calibration and validation issues that must be addressed by model developers, users and decision makers. Despite substantial work on model development, their successful application has been more limited because they are not often used by decision makers for stream and watershed assessment and restoration. Bringing together scientists, model developers, users and decision makers should stimulate the development of appropriate models and improve the applicability of their results. To address these issues, the USEPA Ofﬁce of Research and Development and Region 8 (Colorado, Montana, North Dakota, South Dakota, Utah and Wyoming) hosted a workshop in Denver, Colorado on February 13–14, 2007. The workshop brought together approximately 35 experts from government, academia and consulting to address the state of the art for modelling metals fate and transport, knowledge gaps and future directions in metals modelling. It focused on modelling metals in high-altitude streams, rivers and watersheds impacted by mine waste that are common in the western United States and require remediation. For example, there are over 100 000 abandoned or inactive mining sites across the United States, encompassing over 500 000 acres of land that may eventually require characterization and remediation, including the possible application of stream or watershed metals fate and transport modelling (USEPA, 1997a). This article provides a general overview of the state of the science on modelling metals fate and transport in streams and watersheds, including a review of presentations and discussions at the USEPA workshop. It builds on previous summaries of metals fate and transport models in aquatic systems, including USEPA (1997b, 2007), Allen (2002), Paquin et al. (2003), Nordstrom (2004) and Maest et al. (2005).

Colorado↗

USGS2011

New global hydrography derived from spaceborne elevation data

To study the Earth system and to better understand the implications of global environmental change, there is a growing need for large-scale hydrographic data sets that serve as prerequisites in a variety of analyses and applications, ranging from regional watershed and freshwater conservation planning to global hydrological, climate, biogeochemical, and land surface modeling. Yet while countless hydrographic maps exist for well-known river basins and individual nations, there is a lack of seamless high-quality data on large scales such as continents or the entire globe. Data for many large international basins are patchy, and remote areas are often poorly mapped. In response to these limitations, a team of scientists has developed data and created maps of the world's rivers that provide the research community with more reliable information about where streams and watersheds occur on the Earth's surface and how water drains the landscape. The new product, known as HydroSHEDS (Hydrological Data and Maps Based on Shuttle Elevation Derivatives at Multiple Scales), provides this information at a resolution and quality unachieved by previous global data sets, such as HYDRO1k [ U.S. Geological Survey (USGS) , 2000].

Eos, Transactions, American Geophysical Union↗

USGS2007

Methods of analysis by the U.S. Geological Survey Organic Geochemistry Research Group--Determination of dissolved isoxaflutole and its sequential degradation products, diketonitrile and benzoic acid, in water using solid-phase extraction and liquid chromatography/tandem mass spectrometry

An analytical method for the determination of isoxaflutole and its sequential degradation products, diketonitrile and a benzoic acid analogue, in filtered water with varying matrices was developed by the U.S. Geological Survey Organic Geochemistry Research Group in Lawrence, Kansas. Four different water-sample matrices fortified at 0.02 and 0.10 ug/L (micrograms per liter) are extracted by vacuum manifold solid-phase extraction and analyzed by liquid chromatography/tandem mass spectrometry using electrospray ionization in negative-ion mode with multiple-reaction monitoring (MRM). Analytical conditions for mass spectrometry detection are optimized, and quantitation is carried out using the following MRM molecular-hydrogen (precursor) ion and product (p) ion transition pairs: 357.9 (precursor), 78.9 (p), and 277.6 (p) for isoxaflutole and diketonitrile, and 267.0 (precursor), 159.0 (p), and 223.1 (p) for benzoic acid. 2,4-dichlorophenoxyacetic acid-d3 is used as the internal standard, and alachlor ethanesulfonic acid-d5 is used as the surrogate standard. Compound detection limits and reporting levels are calculated using U.S. Environmental Protection Agency procedures. The mean solid-phase extraction recovery values ranged from 104 to 108 percent with relative standard deviation percentages ranging from 4.0 to 10.6 percent. The combined mean percentage concentration normalized to the theoretical spiked concentration of four water matrices analyzed eight times at 0.02 and 0.10 ug/L (seven times for the reagent-water matrix at 0.02 ug/L) ranged from approximately 75 to 101 percent with relative standard deviation percentages ranging from approximately 3 to 26 percent for isoxaflutole, diketonitrile, and benzoic acid. The method detection limit (MDL) for isoxaflutole and diketonitrile is 0.003 ug/L and 0.004 ug/L for benzoic acid. Method reporting levels (MRLs) are 0.011, 0.010, and 0.012 ug/L for isoxaflutole, diketonitrile, and benzoic acid, respectively. On the basis of the calculated MRLs and MDLs and evaluation of the signal-to-noise ratios for each compound, the MRLs and MDLs are set at 0.010 and 0.003 ug/L, respectively, for all three compounds.

Techniques and Methods↗

USGS2000

A Retrospective Analysis on the Occurrence of Arsenic in Ground-Water Resources of the United States and Limitations in Drinking-Water-Supply Characterizations

The Safe Drinking Water Act, as amended in 1996, requires the U.S. Environmental Protection Agency (USEPA) to review current drinking-water standards for arsenic, propose a maximum contaminant level for arsenic by January 1, 2000, and issue a final regulation by January, 2001. Quantification of the national occurrence of targeted ranges in arsenic concentration in ground water used for public drinking-water supplies is an important component of USEPA's regulatory process. Data from the U.S. Geological Survey (USGS) National Water Information System (NWIS) were used in a retrospective analysis of arsenic in the ground-water resources of the United States. The analysis augments other existing sources of data on the occurrence of arsenic collected in ground water at public water-supply systems.The USGS, through its District offices and national programs, has been compiling data for many years on arsenic concentrations collected from wells used for public water supply, research, agriculture, industry, and domestic water supply throughout the United States. These data have been collected for a variety of purposes ranging from simple descriptions of the occurrence of arsenic in local or regional ground-water resources to detailed studies on arsenic geochemistry associated with contamination sites. A total of 18,864 sample locations were selected from the USGS NWIS data base regardless of well type, of which 2,262 were taken from public water-supply sources. Samples with non-potable water (dissolved-solids concentration greater than 2,000 milligrams per liter and water temperature greater than 50o Celsius) were not selected for the retrospective analysis and other criteria for selection included the amount and type of ancillary data available for each sample. The 1,528 counties with sufficient data included 76 percent of all large public water-supply systems (serving more than 10,000 people) and 61 percent of all small public water-supply systems (serving more than 1,000 and less than 10,000 people) in the United States. The arsenic data were summarized for the selected counties by associating the arsenic concentrations measured in the ground-water resource with the numbers and sizes of public water-supply systems using ground water in those counties. Targeted arsenic concentrations of 1, 2, 5, 10, 20, and 50 ug/L were exceeded in the ground-water resource associated with 36, 25, 14, 8, 3, and 1 percent respectively of all public water-supply systems accounted for in the analysis.Contributions to uncertainty such as changes in sampling methods and changes in laboratory reporting appear to be less important to the national occurrence estimates than other factors such as temporal variability in arsenic concentrations at a given well, the types of wells sampled, and density and types of sampling locations. In addition, no attempt was made to quantify arsenic concentrations in relation to depth within aquifers. With these qualifications, the USGS data represent the ground-water resource in general and are not restricted to wells currently used for public drinking-water sources. In this way, the broad spatial extent, large number of water samples, and low detection limits used for the USGS data provide a unique source of information to determine where targeted concentrations of arsenic are likely to occur in the ground-water resources within much of the United States.These results indicate USGS data can be effectively used to augment national estimates of arsenic occurrence in the nation's ground-water resources if limitations are recognized. Existing estimates of the occurrence of arsenic in ground water that are used as a source of drinking water can be supplemented with the USGS arsenic concentration data when associated with the public water-supply data base. One such supplementary application is the additional insight gained by establishing relations between arsenic concentration data in the ground-water resource and small public wat

Water-Resources Investigations Report↗

USGS2015

Temporal and basin-specific population trends of quagga mussels on soft sediment of a multi-basin reservoir

Invasive quagga (Dreissena bugnesis) and zebra (Dreissena ploymorpha) mussels have rapidly spread throughout North America. Understanding the relationships between environmental variables and quagga mussels during the early stages of invasion will help management strategies and allow researchers to predict patterns of future invasions. Quagga mussels were detected in Lake Mead, NV/AZ in 2007, we monitored early invasion dynamics in 3 basins (Boulder Basin, Las Vegas Bay, Overton Arm) bi-annually from 2008-2011. Mean quagga density increased over time during the first year of monitoring and stabilized for the subsequent two years at the whole-lake scale (8 to 132 individuals·m-2, geometric mean), in Boulder Basin (73 to 875 individuals·m-2), and in Overton Arm(2 to 126 individuals·m-2). In Las Vegas Bay, quagga mussel density was low (9 to 44 individuals·m-2), which was correlated with high sediment metal concentrations and warmer (> 30°C) water temperatures associated with that basin. Carbon content in the sediment increased with depth in Lake Mead and during some sampling periods quagga density was also positively correlated with depth, but more research is required to determine the significance of this interaction. Laboratory growth experiments suggested that food quantity may limit quagga growth in Boulder Basin, indicating an opportunity for population expansion in this basin if primary productivity were to increase, but was not the case in Overton Arm. Overall quagga mussel density in Lake Mead is highly variable and patchy, suggesting that temperature, sediment size, and sediment metal concentrations, and sediment carbon content all contribute to mussel distribution patterns. Quagga mussel density in the soft sediment of Lake Mead expanded during initial colonization, and began to stabilize approximately 3 years after the initial invasion.

Book chapter↗

USGS2025

Searching for seismic precursors - The Barry Landslide hazard clean up

The Barry Landslide, located in Barry Arm of Prince William Sound, Alaska, poses a major hazard due to its steep, unstable slopes and the potential for a massive landslide-generated tsunami. With an estimated volume of 500–700 million cubic meters, the Barry Landslide could trigger highly destructive waves. In this study, we focus on seismic signals from the Barry Landslide, which are critical for providing timely tsunami warnings. Since the summer of 2020, the region has been instrumented to monitor the landslide, but the seismic record is complicated by the presence of nearby glaciers and frequent regional earthquakes. Among these signals, we analyze a specific class of short-duration, high-frequency seismic events that exhibit strong seasonal variability, increasing in rate from late summer to mid-winter before ceasing abruptly in late winter or early spring. Our analysis suggests that the source of these signals is likely near or beneath Cascade Glacier, adjacent to the landslide, rather than within the landslide mass itself. We apply detection algorithms to construct a time history for this signal type, which we then compare with environmental factors like precipitation, temperature, and slope displacement data from ground-based radar and remote sensing. Correlations indicate that these seismic events may be driven by seasonal hydrological changes, particularly the freeze-up of subglacial water pathways. While these events are not directly linked to landslide motion, they serve as indirect markers of subsurface hydrological conditions that influence slope stability. Our findings highlight the complex interplay between glaciers, groundwater, and landslide dynamics, emphasizing the need for multi-parameter monitoring to assess evolving geohazards in the region.

Alaska↗

USGS2003

Changing anthropogenic influence on the Santa Monica Bay watershed

Santa Monica Bay is an open coastal embayment located directly seaward of Los Angeles, California. The Bay provides vital economic value through its water-dependent activities, such as swimming, diving, boating, and fishing. An increase from 100,000 residents in 1900 to 10 million in 2000 has imposed numerous environmental stressors on the Bay, including urbanization of the watershed. Pollutant discharges into the Bay increased throughout the early part of the century, but declined following passage of the Clean Water Act in 1972. Since that time, the predominant source of pollutant inputs has changed from point sources to non-point urban runoff. To assess how present-day and historical pollution interact to affect the environmental quality of Santa Monica Bay, three organizations collaborated on a multi-disciplinary study in 1997, towards which this volume is focused. This paper details the temporal patterns of anthropogenic influence on Santa Monica Bay to provide context for the papers that follow.

California↗

USGS2001

Evaluation of USEPA method 1622 for detection of Cryptosporidium oocysts in stream waters

To improve surveillance for Cryptosporidium oocysts in water, the US Environmental Protection Agency developed method 1622, which consists of filtration, concentration, immunomagnetic separation, fluorescent antibody and 4, 6-diamidino-2-phenylindole (DAPI) counter-staining, and microscopic evaluation. Two filters were compared for analysis of 11 stream water samples collected throughout the United States. Replicate 10-L stream water samples (unspiked and spiked with 100–250 oocysts) were tested to evaluate matrix effects. Oocyst recoveries from the stream water samples averaged 22% (standard deviation [SD] = ±17%) with a membrane disk and 12% (SD = ±6%) with a capsule filter. Oocyst recoveries from reagent water precision and recovery samples averaged 39% (SD = ±13%) with a membrane disk and 47% (SD = ±19%) with a capsule filter. These results demonstrate that Cryptosporidium oocysts can be recovered from stream waters using method 1622, but recoveries are lower than those from reagent-grade water. This research also evaluated concentrations of indicator bacteria in the stream water samples. Because few samples were oocyst-positive, relationships between detections of oocysts and concentrations of indicator organisms could not be determined.

Journal - American Water Works Association↗

USGS2024

Prioritizing US Geological Survey science on salinization and salinity in candidate and selected priority river basins

The US Geological Survey (USGS) is selecting and prioritizing basins, known as Integrated Water Science basins, for monitoring and intensive study. Previous efforts to aid in this selection process include a scientifically defensible and quantitative assessment of basins facing human-caused water resource challenges (Van Metre et al. in Environmental Monitoring and Assessment , 192(7), 458 2020). In the present work, we explore this ranking process based on water quality considerations, specifically salinity and salinization. We selected top candidate basins to study salinity and salinization issues in 18 hydrologic regions that include 163 candidate basins. Our prioritization is based on quantitative assessment of sources of salinity, drivers of change, and receptors that must respond to those sources and drivers. Source terms represented in the prioritization include geology, depth to brackish groundwater, stream conductivity, chloride in precipitation, urban and agricultural land use, application of road salt as a deicer, and irrigation. Drivers represented in prioritization include changes in chemical weathering as a result of changes in rainwater chemistry. Receptors include measures of water stress, measurements of stream ecological health, and socioeconomic factors. In addition, we present research activities for the USGS on salinity and salinization that can be pursued in these basins including assessment of sources, pathways, and loadings; predicting and understanding changes in sources, peaks, and trends; understanding the components of salinity and mobilization of contaminants; understanding the relationship between salinization and changing ecosystems; and developing knowledge on the causes and distribution of groundwater salinity, brackish water resources, and challenges related to desalination.

Enviornmental Monitoring and Assessment↗

USGS2000

The materials flow of mercury in the economies of the United States and the world

Although natural sources of mercury exist in the environment, measured data and modeling results indicate that the amount of mercury released into the biosphere has increased since the beginning of the industrial age. Mercury is naturally distributed in the air, water, and soil in minute amounts, and can be mobile within and between these media. Because of these properties and the subsequent impacts on human health, mercury was selected for an initial materials flow study, focusing on the United States in 1990. This study was initiated to provide a current domestic and international analysis. As part of an increased emphasis on materials flow, this report researched changes and identified the associated trends in mercury flows; it also updates statistics through 1996. In addition to domestic flows, the report includes an international section, because all primary mercury-producing mines are currently foreign, 86 percent of the mercury cell sector of the worldwide chlor-alkali industry is outside the United States, there is a large international mercury trade (1,395 t 1 in 1996), and environmental regulations are not uniform or similarly enforced from country to country. Environmental concerns have brought about numerous regulations that have dramatically decreased both the use and the production of mercury since the late 1980?s. Our study indicates that this trend is likely to continue into the future, as the world eliminates the large mercury inventories that have been stockpiled to support prior industrial processes and products.

Circular↗

USGS2008

Preliminary Map of Potentially Karstic Carbonate Rocks in the Central and Southern Appalachian States

Karst is a landscape produced by dissolution of rocks and the development of integrated subterranean drainages dominated by the flow of ground water in solutionally enlarged conduits. Karst landscapes typically include cave entrances, sinkholes, blind valleys, losing streams, springs, and large and small-scale solution features on bedrock surfaces. Water-bearing rocks beneath the surface containing solutionally enlarged pores, fractures, or conduits are referred to as karst aquifers. About 40 percent of all ground water extracted in the United States comes from karst aquifers (Karst Waters Institute). Karst means many things to many people. To most cavers and many speleologists, karst means areas containing caves. To engineers, home builders, local governments, and insurance companies, karst is exemplified by the occurrence of sinkholes and subsidence hazard. To hydrologists, well drillers, and environmental consultants, the focus on karst may be more limited to karst aquifers and springs. Precise figures are not available, but ground collapses in karst areas in the United States require hundreds of millions of dollars in repair and mitigation costs each year. Most karst in the United States is formed in either carbonate or evaporite rocks. This map depicts only areas of carbonate rock outcrop, the chief host for karst formation in the eastern United States. The U.S. Geological Survey (USGS), in cooperation with the National Cave and Karst Research Institute (NCKRI), the National Speleological Society (NSS), and various State geological surveys, is working on a new national karst map that will delineate areas of karst and karst-like features nationwide. This product attempts to identify potentially karstic areas of the Appalachian states as defined by the Appalachian Regional Commission (ARC), with the addition of the state of Delaware. This map is labeled preliminary because there is an expectation that it will be revised and updated as part of a new national karst map.

Open-File Report↗

USGS2015

Using satellite images to monitor glacial-lake outburst floods: Lago Cachet Dos drainage, Chile

The U.S. Geological Survey (USGS) is monitoring and analyzing glacial-lake outburst floods (GLOFs) in the Colonia valley in the Patagonia region of southern Chile. A GLOF is a type of flood that occurs when water impounded by a glacier or a glacial moraine is released catastrophically. In the Colonia valley, GLOFs originating from Lago Cachet Dos, which is dammed by the Colonia Glacier, have recurred periodically since 2008. The water discharged during these GLOFs flows under or through the Colonia Glacier, into Lago Colonia and then the Río Colonia, and finally into the Río Baker—Chile's largest river in terms of volume of water. This report presents a GeoEye-1 image collected December 1, 2011 and a WorldView-2 image collected September 27, 2013. The 2011 image shows Lago Cachet Dos when the water level was near its maximum extent. The 2013 image shows the drained lake four days after a GLOF event. The images were used to delineate the differences in water surface area prior to, and immediately following, a GLOF event. The imagery shown here highlights the dramatic changes that typically occur during GLOFs from Lago Cachet Dos. The lake area decreased from 4.84 km 2 in 2011 (pre-GLOF) to only 0.30 km 2 in September 2013 (post-GLOF). The water surface lowered approximately 90 m between the pre- and post-GLOF satellite images, yielding a change in volume of approximately 217,000,000 m 3 ; this value is similar to previous estimates (about 200 million m 3 ) of the volume of flood water that flowed down the Río Colonia during some previous GLOFs. During 2008–2013, 14 GLOFs were released from Lago Cachet Dos and created environmental and safety concerns for downstream residents and to infrastructure. If GLOFs and the consequent headward erosion continue, the moraine that creates Lago Cachet Uno could be destabilized and breached, and the two lakes could merge. If the two lakes become connected, the volume of future GLOFs likely would be greater and thus cause longer and (or) more extensive flooding downstream. Additional GLOFs from Lago Cachet Dos are expected in the future, and continued environmental monitoring could provide an early warning system as well as scientific information that could increase our understanding of GLOFs and their consequences. GLOFs occur in glaciated areas around the world and remote sensing technologies can allow researchers to better understand—and potentially predict—future GLOF events.

Colonia valley, Lago Cachet Dos, Patagonia↗

USGS2023

Environmental antimicrobial resistance gene detection from wild bird habitats using two methods: A commercially available culture-independent qPCR assay and culture of indicator bacteria followed by whole-genome sequencing

Objectives A variety of methods have been developed to detect antimicrobial resistance (AMR) in different environments to better understand the evolution and dissemination of this public health threat. Comparisons of results generated using different AMR detection methods, such as quantitative PCR (qPCR) and whole-genome sequencing (WGS), are often imperfect, and few studies have analysed samples in parallel to evaluate differences. In this study, we compared bacterial culture and WGS to a culture-independent commercially available qPCR assay to evaluate the concordance between methods and the utility of each in answering research questions regarding the presence and epidemiology of AMR in wild bird habitats. Methods We first assessed AMR gene detection using qPCR in 45 bacterial isolates from which we had existing WGS data. We then analysed 52 wild bird faecal samples and 9 spatiotemporally collected water samples using culture-independent qPCR and WGS of phenotypically resistant indicator bacterial isolates. Results Overall concordance was strong between qPCR and WGS of bacterial isolates, although concordance differed among antibiotic classes. Analysis of wild bird faecal and water samples revealed that more samples were determined to be positive for AMR via qPCR than via culture and WGS of bacterial isolates, although qPCR did not detect AMR genes in two samples from which phenotypically resistant isolates were found. Conclusions Both qPCR and culture followed by sequencing may be effective approaches for characterising AMR genes harboured by wild birds, although data streams produced using these different tools may have advantages and disadvantages that should be considered given the application and sample matrix.

Journal of Global Antimicrobial Resistance↗

USGS1989

Development of a benthic invertebrate objective for mesotrophic Great Lakes waters

A biological indicator of mesotrophic conditions should (1) provide an appropriate and interpretable objective; (2) be achievable if corrective measures are taken (i.e., it should be within the expected environmental range of the system); and (3) allow measurement of progress toward the objective. Historical data from the Great Lakes suggest that population density of the burrowing mayfly, Hexagenia limbata , could provide an appropriate objective, and that the tubificid oligochaete community can be used to evaluate progress toward that objective. Finally, data from other systems show that Hexagenia can return to locations where it was formerly abundant, and therefore is an attainable objective for formerly mesotrophic ecosystems.

Journal of Great Lakes Research↗

USGS2014

Uncertainty, robustness, and the value of information in managing a population of northern bobwhites

The abundance of northern bobwhites (Colinus virginianus) has decreased throughout their range. Managers often respond by considering improvements in harvest and habitat management practices, but this can be challenging if substantial uncertainty exists concerning the cause(s) of the decline. We were interested in how application of decision science could be used to help managers on a large, public management area in southwestern Florida where the bobwhite is a featured species and where abundance has severely declined. We conducted a workshop with managers and scientists to elicit management objectives, alternative hypotheses concerning population limitation in bobwhites, potential management actions, and predicted management outcomes. Using standard and robust approaches to decision making, we determined that improved water management and perhaps some changes in hunting practices would be expected to produce the best management outcomes in the face of uncertainty about what is limiting bobwhite abundance. We used a criterion called the expected value of perfect information to determine that a robust management strategy may perform nearly as well as an optimal management strategy (i.e., a strategy that is expected to perform best, given the relative importance of different management objectives) with all uncertainty resolved. We used the expected value of partial information to determine that management performance could be increased most by eliminating uncertainty over excessive-harvest and human-disturbance hypotheses. Beyond learning about the factors limiting bobwhites, adoption of a dynamic management strategy, which recognizes temporal changes in resource and environmental conditions, might produce the greatest management benefit. Our research demonstrates that robust approaches to decision making, combined with estimates of the value of information, can offer considerable insight into preferred management approaches when great uncertainty exists about system dynamics and the effects of management.

Florida↗

USGS2024

Economic losses to inland recreational fisheries from harmful algal blooms

This paper presents research on the recreational impacts of harmful algal blooms (HABs) and other water quality changes in the U.S. heartland. We examine the link between recreational fishing and water quality using a random utility model of reservoir choices, and data on effort and health-based advisories for reservoirs in Nebraska. We find that advisories linked specifically to algal blooms affect the demand for and value of fishing, and that these effects are heterogeneous. The estimated welfare loss at HAB-afflicted reservoirs is approximately $12 per trip, with larger losses experienced by gamefish-oriented and college-educated fishers.

Journal of Environmental Management↗