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At least 847 records · Page 47Linked to original sources
USGS2000

Recent research on the hydrodynamics of the Sacramento - San Joaquin River Delta and north San Francisco Bay

This article presents an overview of recent findings from hydrodynamic research on circulation and mixing in the Sacramento-San Joaquin Delta (Delta) (Figure 1) and North San Francisco Bay (North Bay) (Figure 2). For the purposes of this article, North Bay includes San Pablo Bay, Carquinez Strait, and Suisun Bay. The findings presented are those gained from field studies carried out by the U.S. Geological Survey (USGS), as part of the Interagency Ecological Program (IEP), and Stanford University beginning about 1993. The premise behind these studies was that a basic understanding of circulation and mixing patterns in the Bay and Delta is an essential part of understanding how biota and water quality are affected by natural hydrologic variability, water appropriation, and development activities. Data collected for the field studies described in this article have significantly improved our understanding of Bay and Delta hydrodynamics. Measured flows ,in the Delta have provided valuable information on how water moves through the Delta's network of channels and how export pumping affects flows. Studies of the shallows and shallow-channel exchange processes conducted in Honker Bay have shown that the water residence time in Honker Bay is much shorter than previously reported (on the order of hours to several tidal cycles instead ofweeks). Suisun Bay studies have provided data on hydrodynamic transport and accumulation mechanisms that operate primarily in the channels. The Suisun Bay studies have caused us to revise our understanding of residual circulation in the channels of North Bay and of "entrapment" mechanisms in the low salinity zone. Finally, detailed tidal and residual (tidally averaged) time-scale studies of the mechanisms that control gravitational circulation in the estuary show that density-driven transport in the channels is governed by turbulence time-scale (seconds) interactions between the mean flow and stratification. The hydrodynamic research summarized in this article spans a range of estuarine environments (deep water channels to shallow water habitats and brackish water to freshwater) at time scales that range from seconds to years.

California↗
USGS2010

Computer simulation of reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout

This report describes the application of a computer model to simulate reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout. Reservoir and fluid data used for model development are based on (1) information released in BP's investigation report of the incident, (2) information provided by BP personnel during meetings in Houston, Texas, and (3) calibration by history matching to shut-in pressures measured in the capping stack during the Well Integrity Test. The model is able to closely match the measured shut-in pressures. In the simulation of the 86-day period from the blowout to shut in, the simulated reservoir pressure at the well face declines from the initial reservoir pressure of 11,850 pounds per square inch (psi) to 9,400 psi. After shut in, the simulated reservoir pressure recovers to a final value of 10,300 psi. The pressure does not recover back to the initial pressure owing to reservoir depletion caused by 86 days of oil discharge. The simulated oil flow rate declines from 63,600 stock tank barrels per day just after the Deepwater Horizon blowout to 52,600 stock tank barrels per day just prior to shut in. The simulated total volume of oil discharged is 4.92 million stock tank barrels. The overall uncertainty in the simulated flow rates and total volume of oil discharged is estimated to be + or - 10 percent.

Open-File Report↗
USGS2007

Ground-Water Flow Model for the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

This report presents a computer model of ground-water flow in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer in Spokane County, Washington, and Bonner and Kootenai Counties, Idaho. The aquifer is the sole source of drinking water for more than 500,000 residents in the area. In response to the concerns about the impacts of increased ground-water withdrawals resulting from recent and projected urban growth, a comprehensive study was initiated by the Idaho Department of Water Resources, the Washington Department of Ecology, and the U.S. Geological Survey to improve the understanding of ground-water flow in the aquifer and of the interaction between ground water and surface water. The ground-water flow model presented in this report is one component of this comprehensive study. The primary purpose of the model is to serve as a tool for analyzing aquifer inflows and outflows, simulating the effects of future changes in ground-water withdrawals from the aquifer, and evaluating aquifer management strategies. The scale of the model and the level of detail are intended for analysis of aquifer-wide water-supply issues. The SVRP aquifer model was developed by the Modeling Team formed within the comprehensive study. The Modeling Team consisted of staff and personnel working under contract with the Idaho Department of Water Resources, personnel working under contract with the Washington Department of Ecology, and staff of the U.S. Geological Survey. To arrive at a final model that has the endorsement of all team members, decisions on modeling approach, methodology, assumptions, and interpretations were reached by consensus. The ground-water flow model MODFLOW-2000 was used to simulate ground-water flow in the SVPR aquifer. The finite-difference model grid consists of 172 rows, 256 columns, and 3 layers. Ground-water flow was simulated from September 1990 through September 2005 using 181 stress periods of 1 month each. The areal extent of the model encompasses an area of approximately 326 square miles. For the most part, the model extent coincides with the 2005 revised extent of the Spokane Valley-Rathdrum Prairie aquifer as defined in a previous report. However, the model excludes Spirit and Hoodoo Valleys because of uncertainties about the ground-water flow directions in those valleys and the degree of hydraulic connection between the valleys and northern Rathdrum Prairie. The SVRP aquifer is considered to be a single hydrogeologic unit except in Hillyard Trough and the Little Spokane River Arm. In those areas, a continuous clay layer divides the aquifer into an upper, unconfined unit and a lower, confined unit. The model includes all known components of inflows to and outflows from the aquifer. Inflows to the SVRP aquifer include (1) recharge from precipitation, (2) inflows from tributary basins and adjacent uplands, (3) subsurface seepage and surface overflows from lakes that border the aquifer, (4) flow from losing segments of the Spokane River to the aquifer, (5) return percolation from irrigation, and (6) effluent from septic systems. Outflows from the SVRP aquifer include (1) ground-water withdrawals from wells, (2) flow from the aquifer to gaining segments of the Spokane River, (3) aquifer discharge to the Little Spokane River, and (4) subsurface outflow from the lower unit at the western limit of the model area near Long Lake. These inflow and outflow components are represented in the model by using MODFLOW-2000 packages. The parameter-estimation program PEST was used to calibrate the SVRP aquifer model. PEST implements a nonlinear least-squares regression method to estimate model parameters so that the differences between measured and simulated quantities are minimized with respect to an optimal criterion. Calibration data include 1,573 measurements of water levels and 313 measurements of streamflow gains and losses along segments of the Spokane and Little Spokane Rivers. Model parameters estimated during calib

Scientific Investigations Report↗
USGS2011

Proceedings of the Klamath Basin Science Conference, Medford, Oregon, February 1-5, 2010

This report presents the proceedings of the Klamath Basin Science Conference (February 2010). A primary purpose of the meeting was to inform and update Klamath Basin stakeholders about areas of scientific progress and accomplishment during the last 5 years. Secondary conference objectives focused on the identification of outstanding information needs and science priorities as they relate to whole watershed management, restoration ecology, and possible reintroduction of Pacific salmon associated with the Klamath Basin Restoration Agreement (KBRA). Information presented in plenary, technical, breakout, and poster sessions has been assembled into chapters that reflect the organization, major themes, and content of the conference. Chapter 1 reviews the major environmental issues and resource management and other stakeholder needs of the basin. Importantly, this assessment of information needs included the possibility of large-scale restoration projects in the future and lessons learned from a case study in South Florida. Other chapters (2-6) summarize information about key components of the Klamath Basin, support conceptual modeling of the aquatic ecosystem (Chapter 7), and synthesize our impressions of the most pressing science priorities for management and restoration. A wealth of information was presented at the conference and this has been captured in chapters addressing environmental setting and human development of the basin, hydrology, watershed processes, fishery resources, and potential effects from climate change. The final chapter (8) culminates in a discussion of many specific research priorities that relate to and bookend the broader management needs and restoration goals identified in Chapter 1. In many instances, the conferees emphasized long-term and process-oriented approaches to watershed science in the basin as planning moves forward.

California, Oregon↗
USGS2008

Bathymetric Surveys of Lake Arthur and Raccoon Lake, Pennsylvania, June 2007

In spring of 2007, bathymetric surveys of two Pennsylvania State Park lakes were performed to collect accurate data sets of lake-bed elevations and to develop methods and techniques to conduct similar surveys across the state. The lake-bed elevations and associated geographical position data can be merged with land-surface elevations acquired through Light Detection and Ranging (LIDAR) techniques. Lake Arthur in Butler County and Raccoon Lake in Beaver County were selected for this initial data-collection activity. In order to establish accurate water-surface elevations during the surveys, benchmarks referenced to NAVD 88 were established on land at each lake by use of differential global positioning system (DGPS) surveys. Bathymetric data were collected using a single beam, 210 kilohertz (kHz) echo sounder and were coupled with the DGPS position data utilizing a computer software package. Transects of depth data were acquired at predetermined intervals on each lake, and the shoreline was delineated using a laser range finder and compass module. Final X, Y, Z coordinates of the geographic positions and lake-bed elevations were referenced to NAD 83 and NAVD 88 and are available to create bathymetric maps of the lakes.

Data Series↗
USGS2006

Aeromagnetic survey of Dillingham area in southwest Alaska, a website for the preliminary distribution of data

An airborne high-resolution magnetic survey was completed over the Dillingham and Nushagak Bay and Naknek area in southwestern Alaska. The flying was undertaken by McPhar Geosurveys Ltd. on behalf of the United States Geological Survey (USGS). First tests and calibration flights were completed by August 26th, 2005 and data acquisition was initiated on September 1st, 2005. The final data acquisition flight was completed on October 22nd, 2005. A total of 8,630 line-miles of data were acquired during the survey.

Alaska↗
USGS1993

Hydrogeology and water quality of the Galena-Platteville aquifer at the Parson's Casket Hardware Superfund site, Belvidere, Illinois, 1991-92

The purpose of this letter is to describe the results of the final phase (phase 3) of the U.S. Geological Survey's (USGS) ground-water investigation at the Parson's Casket Hardware site, Belvidere, Ill. (figs. 1 and 2), for the U.S. Environmental Protection Agency (USEPA). Included in this letter are brief descriptions of (1) study methods employed in the phase 3 investigation that have not been previously described in earlier reports, and (2) results of the phase 3 investigation as they relate to the results of the previous phases of the investigation. The data from the phase 3 investigation that are presented and described herein were collected during November 1991-January 1992. The Galena-Platteville aquifer is the uppermost bedrock aquifer beneath the site. The Glenwood Formation of Ordovician age, a potential confining unit, separates the Galena-Platteville aquifer from the underlying St. Peter Sandstone aquifer (fig. 3). The St. Peter Sandstone aquifer is an important source of ground water to Belvidere and other cities in the region. The phase 3 investigation was done (1) to determine the lithology of the Glenwood Formation; (2) to determine the vertical distribution of horizontal hydraulic conductivity (K) and concentrations of volatile organic compounds (VOC's) in the upper 150 ft (feet) of the Galena-Platteville aquifer at an existing monitoring location, borehole G127GP (figs. 2 and 3) ; and (3) to confirm the presence or absence of VOC's in the St. Peter Sandstone aquifer at a new monitoring location, well G127SP (figs. 2 and 3). Additional components of the site investigation described in this letter include determination of vertical hydraulic gradients between the Galena-Platteville and St. Peter Sandstone aquifers and in situ measurement of selected water-quality characteristics (pH, temperature, specific conductance, Eh, and dissolved oxygen) in borehole G127GP. The results of the first and second phases of the USGS investigation at the Parson's Casket Hardware site are presented in two previous USGS Open-File Reports prepared for the USEPA (Mills, 1993a, 1993b) . These reports describe the hydrogeology of the study site, principally the Galena-Platteville aquifer, and the distribution of VOC concentrations in the Galena-Platteville aquifer. (The stratigraphic nomenclature used in this report is that of the Illinois State Geological Survey (Willman and others, 1975, p. 47-87) and does not necessarily follow the usage of the USGS. The aquifer nomenclature is that generally used by the Illinois State Geological Survey and the U.S. Environmental Protection Agency.) The previous two reports also describe most of the study methods employed in the phase 3 investigation.

Open-File Report↗
USGS2006

Statewide analysis of the drainage-area ratio method for 34 streamflow percentile ranges in Texas

The drainage-area ratio method commonly is used to estimate streamflow for sites where no streamflow data are available using data from one or more nearby streamflow-gaging stations. The method is intuitive and straightforward to implement and is in widespread use by analysts and managers of surface-water resources. The method equates the ratio of streamflow at two stream locations to the ratio of the respective drainage areas. In practice, unity often is assumed as the exponent on the drainage-area ratio, and unity also is assumed as a multiplicative bias correction. These two assumptions are evaluated in this investigation through statewide analysis of daily mean streamflow in Texas. The investigation was made by the U.S. Geological Survey in cooperation with the Texas Commission on Environmental Quality. More than 7.8 million values of daily mean streamflow for 712 U.S. Geological Survey streamflow-gaging stations in Texas were analyzed. To account for the influence of streamflow probability on the drainage-area ratio method, 34 percentile ranges were considered. The 34 ranges are the 4 quartiles (0-25, 25-50, 50-75, and 75-100 percent), the 5 intervals of the lower tail of the streamflow distribution (0-1, 1-2, 2-3, 3-4, and 4-5 percent), the 20 quintiles of the 4 quartiles (0-5, 5-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-55, 55-60, 60-65, 65-70, 70-75, 75-80, 80-85, 85-90, 90-95, and 95-100 percent), and the 5 intervals of the upper tail of the streamflow distribution (95-96, 96-97, 97-98, 98-99 and 99-100 percent). For each of the 253,116 (712X711/2) unique pairings of stations and for each of the 34 percentile ranges, the concurrent daily mean streamflow values available for the two stations provided for station-pair application of the drainage-area ratio method. For each station pair, specific statistical summarization (median, mean, and standard deviation) of both the exponent and bias-correction components of the drainage-area ratio method were computed. Statewide statistics (median, mean, and standard deviation) of the station-pair specific statistics subsequently were computed and are tabulated herein. A separate analysis considered conditioning station pairs to those stations within 100 miles of each other and with the absolute value of the logarithm (base-10) of the ratio of the drainage areas greater than or equal to 0.25. Statewide statistics of the conditional station-pair specific statistics were computed and are tabulated. The conditional analysis is preferable because of the anticipation that small separation distances reflect similar hydrologic conditions and the observation of large variation in exponent estimates for similar-sized drainage areas. The conditional analysis determined that the exponent is about 0.89 for streamflow percentiles from 0 to about 50 percent, is about 0.92 for percentiles from about 50 to about 65 percent, and is about 0.93 for percentiles from about 65 to about 85 percent. The exponent decreases rapidly to about 0.70 for percentiles nearing 100 percent. The computation of the bias-correction factor is sensitive to the range analysis interval (range of streamflow percentile); however, evidence suggests that in practice the drainage-area method can be considered unbiased. Finally, for general application, suggested values of the exponent are tabulated for 54 percentiles of daily mean streamflow in Texas; when these values are used, the bias correction is unity.

Scientific Investigations Report↗
USGS2017

The angus mammoth: A decades-old scientific controversy resolved

The Angus Mammoth site in south-central Nebraska has been controversial since its discovery in 1931 when a fluted artifact was reported to be associated with the mammoth. For nearly 80 years it has not been known if Angus was a paleontological site predating the human occupation of North America as has been asserted by some geologists and paleontologists, or an archaeological site dating to the late Pleistocene as has been advocated by some archaeologists. Geomorphic study and luminescence dating have finally solved the problem after nearly eight decades. Although microwear and technological analyses have determined that the Angus biface is an authentic artifact, TL and IRSL dates have shown that the matrix above the mammoth is much too old for a mammoth/fluted point association to be valid.

Nebraska↗
USGS2024

Expanded conceptual risk framework for uranium mining in Grand Canyon watershed—Inclusion of the Havasupai Tribe perspective

In 2012, the Secretary of the U.S. Department of the Interior placed a 20-year limit on mineral extraction on Federal lands in the Grand Canyon watershed to permit further study of the environmental effects of uranium mining. Tribal concerns were also noted by the U.S. Department of the Interior and included in the rationale for the decision stating Tribal resource impacts could not be mitigated and cultural degradation may result should mining occur within sacred and traditional places of Tribal peoples. The U.S. Geological Survey previously developed a conceptual framework for a uranium mine in the region that defined contaminant sources and physical, chemical, and biological processes that affect contaminant transport to ecological receptors. However, published risk models have largely ignored exposure pathways relevant to Tribal communities in terms of traditional uses and existential values of the resources included. This report presents an updated conceptual risk framework for uranium mining that includes indigenous knowledge components informed by the Havasupai Tribe perspective. The expansion of the framework relied on connecting to the foundations of the Havasupai ceremonial wheel—food, environment, belief system, and ceremony. The framework is applied to uranium development near Red Butte, an important gathering place for multiple federally recognized Tribes including the Havasupai, Hopi, Navajo, and Zuni. Plants and animals important to the Havasupai for subsistence, ceremonial, and medicinal practices and how mining affects these practices are described. The final framework is presented in English and Havasupai to aid Tribal members in understanding how the framework relates to their community and to help preserve the language and historical cultural practices for future generations. New or expanded exposure pathways include inhalation, ingestion, and absorption from traditional food and medicines as well as ceremonial practices. The updated framework has allowed the U.S. Geological Survey to take first steps in understanding resources important to the Havasupai and to build relationships to improve co-production in our research. Ideally, the framework and other research can be used, along with indigenous knowledge, in Federal research and decision making for mining in the Grand Canyon region.

Open-File Report↗
USGS2023

Development and application of a coastal change likelihood assessment for the northeast region, Maine to Virginia

Coastal resources are increasingly affected by erosion, extreme weather events, sea level rise, tidal flooding, and other potential hazards related to climate change. These hazards have varying effects on coastal landscapes because of the compounding of geologic, oceanographic, ecologic, and socioeconomic factors that exist at a given location. An assessment framework is introduced in this report that synthesizes existing datasets that cover the variability of the landscape, and hazards that may act on the landscape, to evaluate the likelihood of coastal change along the U.S. coastline on a decadal scale. The pilot study that aided in the development of the framework was run in the northeastern United States (from Maine to Virginia) and consists of datasets derived from a variety of Federal, State, and local sources. First, a decision-tree-based dataset was built that describes the resistance or integrity of the coastal landscape (called the fabric dataset for the purposes of this report) and includes land cover, elevation, slope, long-term (more than 50 years) shoreline change, dune height, and marsh stability data. A second database was generated from coastal hazards, which are divided into event hazards (for example, flooding, wave power, and probability of storm overwash) and persistent or perpetual hazards (for example, relative sea level rise rate, short-term [about 30-year] shoreline erosion rate, and storm recurrence interval). The fabric dataset was then merged with the coastal hazards databases, and a model training dataset made up of hundreds of polygons was generated from these combined data to support machine learning. The pilot study resulted in location-specific, 10-meter-resolution data classified into five raster datasets that include intrinsic characteristics of the coast used to determine the resistance of the landscape to change, the persistent and event hazards that act on the coast, the machine learning output (coastal change likelihood) based on the cumulative effects of the fabric and hazards datasets, and an estimate of the hazard type (event or persistent) that is the most likely to influence coastal change. Final outcomes are intended to be used as a first-order planning tool to determine which areas of the coast are more likely to change in response to future potential coastal hazards and to examine elements and drivers that make change in a location more likely.

Connecticut, Delaware, Maine, Maryland, Massachuse↗
USGS2026

Adaptation and response in drylands: A dryland research agenda and campaign strategy

Dryland ecosystems cover 41% of Earth's land surfaces, account for 44% of cultivated lands and 60% of food sources, and make large contributions to the global water and carbon cycles. However, these ecosystems are experiencing unprecedented extremes including heatwaves, floods, and droughts as well as hotter temperatures and often declining water resource availability. These ecosystems are some of the most challenging to monitor given their high temporal variability with rapid response to their environment as well as vast spatial variability with intermixing of different plant species and life forms amongst bare soil coverage. The Adaptation and Response in Drylands (ARID) campaign was selected by National Aeronautics and Space Administration (NASA) as a scoping study to develop a research agenda for a dryland field campaign. Here, we detail our ARID science research agenda and implementation plan that were developed based on an extensive community engagement effort in over 160 events with over a thousand scientists, land managers, and Tribal communities between 2023 and 2024. The selected science themes cover drought and climate variability, ecosystem structure, function, and biodiversity, carbon cycle interannual variability and trends, and social ecological systems (land management and adaptation). We then detail our remote sensing, modeling, and field-based strategies to capture high temporal and high spatial resolution processes. Finally, our implementation strategy is presented which includes focus area selections in a core intensive western U.S. domain and distributed international domains. This strategy includes our overarching guiding principles of using multi-temporal airborne acquisitions and super sites as well as enhancing land management in co-development with end-user partners. While originally developed for NASA, our ARID report creates a blueprint for any future dryland field campaign, at any scale, that can be implemented widely for foundational and applied science objectives.

Global Change Biology↗
USGS2016

Bathymetric terrain model of the Atlantic margin for marine geological investigations

A bathymetric terrain model of the Atlantic margin covering almost 725,000 square kilometers of seafloor from the New England Seamounts in the north to the Blake Basin in the south is compiled from existing multibeam bathymetric data for marine geological investigations. Although other terrain models of the same area are extant, they are produced from either satellite-derived bathymetry at coarse resolution (ETOPO1), or use older bathymetric data collected by using a combination of single beam and multibeam sonars (Coastal Relief Model). The new multibeam data used to produce this terrain model have been edited by using hydrographic data processing software to maximize the quality, usability, and cartographic presentation of the combined 100-meter resolution grid. The final grid provides the largest high-resolution, seamless terrain model of the Atlantic margin..

Open-File Report↗
USGS2023

Potential effects of climate change on Ambystoma barbouri (streamside salamander)

Ambystoma barbouri (streamside salamanders) are stream-breeding mole salamanders that rely on seasonally intermittent, fishless streams for egg and larval development but are primarily fossorial as adults. Climate-driven changes are likely to alter streamflow duration, peak, and seasonality within the range of A. barbouri , reducing reproductive habitat and larval survival. Although future changes in precipitation volume within the geographic range of A. barbouri are uncertain, in the next 90 years, increasing temperatures will likely increase potential evapotranspiration. Decreasing ratio of precipitation to potential evapotranspiration will likely shorten flow duration for intermittent streams, potentially causing earlier stream dry downs before larval metamorphosis. Increased temperatures may also shorten developmental periods buffering A. barbouri larvae from the effects of increased stream no-flow days. Additionally, precipitation in the future will increasingly fall in heavy rainfall events. Heavy rain and subsequent flooding during early larval stages may displace A. barbouri larvae from fishless pools into downstream reaches with vertebrate predators that can reduce survival. Finally, agriculture and urban land cover may amplify the stresses of climate change on A. barbouri , altering reproductive habitat and reducing survival of larval, juvenile, and adult life stages.

Illinois, Indiana, Kentucky, Ohio, Tennessee, West↗
USGS2010

Seismic precursors to volcanic explosions during the 2006 eruption of Augustine Volcano: Chapter 2 in The 2006 eruption of Augustine Volcano, Alaska

The 2006 eruption of Augustine Volcano, Alaska, generated more than 3,500 earthquakes in a month-long time frame bracketing the most explosive period of activity. We examine two quantitative tools that, in retrospective analysis, were excellent indicators of imminent eruption. The first tool, referred to as the frequency index ( FI ), is based on a simple ratio of high- and low-frequency energy in an earthquake seismogram. It is a metric that allows us to quantify the differences between the canonical high-frequency, hybrid, and low-frequency volcanic earthquakes. FI values greater than -0.4 indicate earthquakes classically referred to as high-frequency or volcano-tectonic events. FI values less than -1.3 correspond to events usually referred to as low-frequency earthquakes. Because the FI is based on a ratio and not a spectral peak, hybrid earthquakes are successfully assigned FI values intermediate to these two classes. In this eruption, we find a remarkable correlation between events with FI less than -1.8 and explosive eruptions. The second tool we examine is based on repeating seismic waveforms identified through waveform cross-correlation. Although the vast majority of earthquakes during this eruption have unique waveforms, subsets of events exhibiting a high degree of similarity occur and are closely tied to explosive eruption events. Of the 13 large explosion events, seven were preceded by clusters of highly similar earthquakes. We apply the FI and correlation tools together to identify changes in high- and low-frequency earthquake occurrences and examine their relations to the precursory, explosive, and continuous phases of the eruption. We find that earthquakes that have low FI values and earthquakes exhibiting high degrees of similarity occur almost exclusively within hours of explosive eruptions and postulate that they occur as a result of the final ascent of magma in the volcanic edifice. Because neither of these methods requires analyst-reviewed earthquake locations, we believe that they have considerable potential as automated real-time volcano monitoring tools.

Alaska↗
USGS2018

Estimates of long-term mean-annual nutrient loads considered for use in SPARROW models of the Midcontinental region of Canada and the United States, 2002 base year

Streamflow and nutrient concentration data needed to compute nitrogen and phosphorus loads were compiled from Federal, State, Provincial, and local agency databases and also from selected university databases. The nitrogen and phosphorus loads are necessary inputs to Spatially Referenced Regressions on Watershed Attributes (SPARROW) models. SPARROW models are a way to estimate the distribution, sources, and transport of nutrients in streams throughout the Midcontinental region of Canada and the United States. After screening the data, approximately 1,500 sites sampled by 34 agencies were identified as having suitable data for calculating the long-term mean-annual nutrient loads required for SPARROW model calibration. These final sites represent a wide range in watershed sizes, types of nutrient sources, and land-use and watershed characteristics in the Midcontinental region of Canada and the United States.

Scientific Investigations Report↗
USGS1964

Determination of radium in water

Radium isotopes are common radioactive constituents of natural waters. The concentration of radium-226 in potable water is of particular significance because this isotope is generally considered the most hazardous of all radionuclides with respect to ingestion. The approximate concentration of radium-226 is determined after coprecipitating radium with barium sulfate. The short-lived daughters of radium are allowed to grow for 10-12 days, then the alpha activity of the precipitate is measured and compared with that of a precipitate containing a known amount of radium-226. Concentrations of the individual alpha-emitting isotopes of radium-223, radium-224, and radium-226, are determined by coprecipitating radium first with lead sulfate, then with barium chloride, and finally with barium sulfate. This final precipitate is initially free of other alpha-emitting nuclides, thus permitting the isotopic composition to be determined by measuring the growth and decay of the alpha activity of the precipitate.

Water Supply Paper↗
USGS2025

A practical decision tool for marine bird mortality assessments

Given the rise in anthropogenic, environmental, and disease events contributing to marine bird mortality, there is a critical need to improve the rigor of mortality assessments. Deficits in data collection and mortality estimation can hinder a manager’s ability to document event scales and inform population level impacts. Therefore, to inform decisions required during activities such as conservation status assessments or harvest management, organizations may choose to incorporate mortality assessments into response plans. Resources, capacity, and assets to assess mortality vary across jurisdictions (federal, state, Indigenous, local, etc.), and clear guidance to support mortality assessments is often unavailable or not clearly addressed. Here, we present a decision support tool to help managers identify and evaluate survey options to assess bird mortality in a diverse array of scenarios. The objective of the decision tool is to improve data collection and availability which will increase the ability to robustly estimate mortality, given situation-specific attributes and constraints. This decision tool is designed to guide the response when a mortality event is initially encountered and offers suggestions for assessment and reporting procedures in the absence of other guidance or to complement existing protocols. The decision tool is also meant to inform decision making for response determination and resource allocation. The tool facilitates examination of options for further assessment and monitoring which users determine by examining questions pertaining to species prioritization, mortality spatial extent, and the potential magnitude of impacts on affected species. Finally, identification of appropriate survey methods, that address imperfect detection when a complete census is not possible, are determined by exploring location, spatial and temporal extent, and the type of species affected. Ultimately, this tool aims to facilitate and improve the standardization of mortality assessments, equipping managers with a practical resource to navigate the decision-making process for marine bird mortality estimation.

EcoEvoRxiv↗