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At least 1,225 records · Page 68Linked to original sources

USGS2000

Solar electric power for instruments at remote sites

Small photovoltaic (PV) systems are the preferred method to power instruments operating at permanent locations away from the electric power grid. The low-power PV power system consists of a solar panel or small array of panels, lead-acid batteries, and a charge controller. Even though the small PV power system is simple, the job of supplying power at a remote site can be very demanding. The equipment is often exposed to harsh conditions. The site may be inaccessible part of the year or difficult and expensive to reach at any time. Yet the system must provide uninterrupted power with minimum maintenance at low cost. This requires good design. Successful small PV systems often require modifications by a knowledgeable fieldworker to adapt to conditions at the site. Much information is available in many places about solar panels, lead-acid batteries, and charging systems but very little of it applies directly to low power instrument sites. The discussion here aims to close some of the gap. Each of the major components is described in terms of this application with particular attention paid to batteries. Site problems are investigated. Finally, maintenance and test procedures are given. This document assumes that the reader is engaged in planning or maintaining low-power PV sites and has basic electrical and electronic knowledge. The area covered by the discussion is broad. To help the reader with the many terms and acronyms used, they are shown in bold when first used and a glossary is provided at the end of the paper.

Open-File Report↗

USGS2015

GIS-Based Identification of Areas with Mineral Resource Potential for Six Selected Deposit Groups, Bureau of Land Management Central Yukon Planning Area, Alaska

This study, covering the Bureau of Land Management (BLM) Central Yukon Planning Area (CYPA), Alaska, was prepared to aid BLM mineral resource management planning. Estimated mineral resource potential and certainty are mapped for six selected mineral deposit groups: (1) rare earth element (REE) deposits associated with peralkaline to carbonatitic intrusive igneous rocks, (2) placer and paleoplacer gold, (3) platinum group element (PGE) deposits associated with mafic and ultramafic intrusive igneous rocks, (4) carbonate-hosted copper deposits, (5) sandstone uranium deposits, and (6) tin-tungsten-molybdenum-fluorspar deposits associated with specialized granites. These six deposit groups include most of the strategic and critical elements of greatest interest in current exploration. This study has used a data-driven, geographic information system (GIS)-based method for evaluating the mineral resource potential across the large region of the CYPA. This method systematically and simultaneously analyzes geoscience data from multiple geospatially referenced datasets and uses individual subwatersheds (12-digit hydrologic unit codes or HUCs) as the spatial unit of classification. The final map output indicates an estimated potential (high, medium, low) for a given mineral deposit group and indicates the certainty (high, medium, low) of that estimate for any given subwatershed (HUC). Accompanying tables describe the data layers used in each analysis, the values assigned for specific analysis parameters, and the relative weighting of each data layer that contributes to the estimated potential and certainty determinations. Core datasets used include the U.S. Geological Survey (USGS) Alaska Geochemical Database (AGDB2), the Alaska Division of Geologic and Geophysical Surveys Web-based geochemical database, data from an anticipated USGS geologic map of Alaska, and the USGS Alaska Resource Data File. Map plates accompanying this report illustrate the mineral prospectivity for the six deposit groups across the CYPA and estimates of mineral resource potential. There are numerous areas, some of them large, rated with high potential for one or more of the selected deposit groups within the CYPA.

Alaska↗

USGS2015

The Everglades Depth Estimation Network (EDEN) surface-water model, version 2

The Everglades Depth Estimation Network (EDEN) is an integrated network of water-level gages, interpolation models that generate daily water-level and water-depth data, and applications that compute derived hydrologic data across the freshwater part of the greater Everglades landscape. The U.S. Geological Survey Greater Everglades Priority Ecosystems Science provides support for EDEN in order for EDEN to provide quality-assured monitoring data for the U.S. Army Corps of Engineers Comprehensive Everglades Restoration Plan. The EDEN surface-water model, version 2 (V2), interpolates water-level data from a network of 240 gages to generate gridded daily water-level surfaces for the freshwater domain of the Everglades. When these spatiotemporal continuous surfaces are combined with EDEN’s digital elevation model of ground surface, derived hydrologic data provide scientists and water managers working in the Everglades with data necessary to analyze ecological and biotic responses to hydrologic changes in the Everglades. Derived datasets include water depth, recession rates, days since last dry, water-surface slopes, and hydroperiod. The V2 model includes enhancements from the previous model (version 1; V1) to accommodate changes in the water-level gage network, adjustments to water-level data, improved understanding of the flow dynamics (particularly near canals), and installation of an elevation benchmark network. Enhancements to the V2 model included Expansion of the EDEN domain: The model domain was expanded to include a part of southern Big Cypress National Preserve and northwestern Everglades National Park upstream of the marsh mangrove wetlands, thus completing the coastal connection along the southwestern boundary of the model; and Development of subdomain models: To account for insufficient water-control structure gage data at some subbasin boundaries, subdomain models were developed for five subdomains, and the resulting water-level surfaces were merged to generate the final water-level surface. Model performance statistics show a general improvement in the V2 model as compared to the V1 model. Overall, the root mean squared error (RMSE) was reduced by 2.42 centimeters (cm) to 4.68 cm. In Water Conservation Area 3A North and Water Conservation Area 3B, the RMSE was reduced by 10.88 and 9.15 cm, respectively. In addition to evaluating model performance statistics, 2-cm water-level maps were generated and evaluated for irregular contours that would indicate a potential problem either with data input or water-level estimates. Three applications of the EDEN-modeled water surfaces and other EDEN datasets are presented in the report to show how scientists and resource managers are using EDEN datasets to analyze biological and ecological responses to hydrologic changes in the Everglades. The biological responses of two important Everglades species, alligators and wading birds, to changes in hydrology are described. The effects of hydrology on fire dynamics in the Everglades are also discussed.

Florida↗

USGS2011

Seismic-Hazard Maps for the Conterminous United States, 2008

Probabilistic seismic-hazard maps were prepared for the conterminous United States portraying peak horizontal acceleration and horizontal spectral response acceleration for 0.2- and 1.0-second periods with probabilities of exceedance of 10 percent in 50 years and 2 percent in 50 years. All of the maps were prepared by combining the hazard derived from spatially smoothed historic seismicity with the hazard from fault-specific sources. The acceleration values contoured are the random horizontal component. The reference site condition is firm rock, defined as having an average shear-wave velocity of 760 m/s in the top 30 meters corresponding to the boundary between NEHRP (National Earthquake Hazards Reduction program) site classes B and C. This data set represents the results of calculations of hazard curves for a grid of points with a spacing of 0.05 degrees in latitude and longitude. The grid of points were contoured to produce the final representation of the seismic-hazard. These maps are intended to summarize the available quantitative information about seismic ground motion hazard for the conterminous United States from geologic and geophysical source.

Scientific Investigations Map↗

USGS1990

Effects of surface coal mining and reclamation on the geohydrology of six small watersheds in West-Central Indiana

Six small watersheds in west-central Indiana were selected for study of the hydrologic effects of surface coal mining and reclamation. The watersheds include mined and reclaimed, mined and unreclaimed, and unmined agricultural land uses and are each less than 3 square miles in area. Surface-water, ground-water, and meteorologic data for the 1981 and 1982 water years were used to describe and compare hydrologic systems of the six watersheds and to identify hydrologic effects of mining and reclamation. Discharge at the unreclaimed watersheds was continuous during the study period, whereas discharge at the other watersheds was intermittent and more variable. Peak discharges were greater at the agricultural watersheds than at the unreclaimed watersheds, primarily because of large final-cut lakes in the unreclaimed watersheds. Annual runoff was greatest at the unreclaimed watersheds, intermediate at the agricultural watersheds, and least at the reclaimed watersheds. Hydrologic effects of mining were identified by comparing the hydrologic systems at mined and unreclaimed watersheds with those at unmined agricultural watersheds. These comparisons indicate that surface coal mining without reclamation can increase base flow, annual runoff, and ground-water recharge to the bedrock; reduce peak flow rates and variation in flow; lower the water table in upland areas; change the relation between surface- and ground-water divides; and create numerous, local flow systems in the shallow ground water. Hydrologic effects of reclamation were identified by comparing the hydrologic systems at mined and reclaimed watersheds with those at mined and unreclaimed watersheds. Reclamation can decrease base flow, annual runoff, and recharge to the bedrock; increase peak flow rates, variation in flow, and the response to thunderstorms; reestablish the premining relation between surface- and ground-water divides; and create fewer local flow systems in the shallow ground water. Hydrologic effects of mining and reclamation were identified by comparing the hydrologic systems at mined and reclaimed watersheds with those at unmined agricultural watersheds. The presence or absence of a large final-cut lake in the reclaimed watershed greatly influences the hydrologic systems and the effects of mining and reclamation. Surface coal mining and reclamation can decrease base flow, annual runoff, and peak flow rates; increase the variability of flow and recharge to the bedrock; reestablish the premining relation between surface- and ground-water divides; and lower the water table in upland areas.

Indiana↗

USGS1976

Steps to the moon

On July 20, 1969, man walked on the surface of the Moon and began a new chapter of his studies that will eventually disclose the geologic nature of the Earth's nearest neighbor. Although he has finally reached the Moon and sampled its substance, much work and study remain before he will know the full scientific significance of the first landing. This booklet briefly summarizes the steps man has taken to understand the Moon and what he thinks he has learned to date as a result of his centuries-long speculations and studies.

General Information Product↗

USGS1964

Subsurface geology of the upper Cretaceous Kirtland and Fruitland formations of the San Juan Basin, New Mexico and Colorado

The San Juan Basin is an asymmetrical structural basin in northwestern New Mexico and southwestern Colorado. The basin contains sedimentary rocks ranging from Cambrian through Recent in age and attaining a maximum thickness between 14,000 and 15,000 feet. The Upper Cretaceous sedimentary rocks exceed 8,000 feet in thickness and can be divided into two groups: the lower Upper Cretaceous which is composed of the non marine and non-marine rocks and the upper Upper Cretaceous which is composed of the non-marine Kirtland and Fruitland Formations. The Kirtland Shale is subdivided into the lower shale, Farmington Sandstone, and upper shale members. The rocks of the Kirtland and Fruitland Formations consist of fluviatile and flood plain deposits and range in thickness from 1750 feet in the northwest part of the basin to 0 feet on the eastside of the basin. The thinning of the Kirtland and Fruitland Formations from west to east is primarily the result of erosion following tilting of the San Juan Basin area toward the west after either part or all of the upper shale member had been deposited. The overlying Ojo Alamo Sandstone rests on progressively older rocks across the basin overstepping the under lying upper shale member, Farmington Sandstone Member, Fruitland Formation, and finally resting on the Lewis Shale on the east side of the basin. The source area for the rocks of the Kirtland and Fruitland Formations was probably to the north or northwest of the San Juan Basin area. The Kirtland and Fruitland rocks have produced minor amounts of oil and gas. The Fruitland Formation contains large coal deposits some of which are currently being strip mined near Fruitland, New Mexico

Colorado, New Mexico↗

USGS2000

Development of a contour map showing generalized skew coefficients of annual peak discharges of rural, unregulated streams in New York, excluding Long Island

Flood-frequency relations that are developed by fitting the logarithms of annual peak discharges to a Pearson Type-III distribution are sensitive to skew coefficients. Estimates of population skew for a site are improved when computed from the weighted average of (1) the sample (station) skew, and (2) an unbiased, generalized skew estimate. A weighting technique based on the number of years of record at each of 226 sites was used to develop a contour map of unbiased, generalized skew coefficients for New York. An attempt was made to group (regionalize) the station skew coefficients into five hydrologically similar areas of New York, but the statewide version proved to be as accurate as the regionalized version and therefore was adopted as the final generalized skew-coefficient map for New York. An error analysis showed the statewide contour map to have lower MSE?s (mean square errors) than those computed from (1) the five regional skewcoefficient contour maps, (2) a previously used (1982) nationwide skew coefficient map, and (3) the weighted mean of skew coefficients for sites within each of five hydrologically uniform, but distinct areas of New York.

New York↗

USGS2002

Three-dimensional hydrogeologic framework model for use with a steady-state numerical ground-water flow model of the Death Valley regional flow system, Nevada and California

The U.S. Geological Survey, in cooperation with the Department of Energy and other Federal, State, and local agencies, is evaluating the hydrogeologic characteristics of the Death Valley regional ground-water flow system. The ground-water flow system covers an area of about 100,000 square kilometers from latitude 35° to 38°15' North to longitude 115° to 118° West, with the flow system proper comprising about 45,000 square kilometers. The Death Valley regional ground-water flow system is one of the larger flow systems within the Southwestern United States and includes in its boundaries the Nevada Test Site, Yucca Mountain, and much of Death Valley. Part of this study includes the construction of a three-dimensional hydrogeologic framework model to serve as the foundation for the development of a steady-state regional ground-water flow model. The digital framework model provides a computer-based description of the geometry and composition of the hydrogeologic units that control regional flow. The framework model of the region was constructed by merging two previous framework models constructed for the Yucca Mountain Project and the Environmental Restoration Program Underground Test Area studies at the Nevada Test Site. The hydrologic characteristics of the region result from a currently arid climate and complex geology. Interbasinal regional ground-water flow occurs through a thick carbonate-rock sequence of Paleozoic age, a locally thick volcanic-rock sequence of Tertiary age, and basin-fill alluvium of Tertiary and Quaternary age. Throughout the system, deep and shallow ground-water flow may be controlled by extensive and pervasive regional and local faults and fractures. The framework model was constructed using data from several sources to define the geometry of the regional hydrogeologic units. These data sources include (1) a 1:250,000-scale hydrogeologic-map compilation of the region; (2) regional-scale geologic cross sections; (3) borehole information, and (4) gridded surfaces from a previous three-dimensional geologic model. In addition, digital elevation model data were used in conjunction with these data to define ground-surface altitudes. These data, properly oriented in three dimensions by using geographic information systems, were combined and gridded to produce the upper surfaces of the hydrogeologic units used in the flow model. The final geometry of the framework model is constructed as a volumetric model by incorporating the intersections of these gridded surfaces and by applying fault truncation rules to structural features from the geologic map and cross sections. The cells defining the geometry of the hydrogeologic framework model can be assigned several attributes such as lithology, hydrogeologic unit, thickness, and top and bottom altitudes.

California, Nevada↗

USGS2016

Case study: 2016 Natural glide and wet slab avalanche cycle, Going-to-the-Sun Road, Glacier National Park, Montana, USA

The Going-to-the-Sun Road (GTSR) is the premier tourist attraction in Glacier National Park, Montana. The GTSR also traverses through and under 40 avalanche paths which pose a hazard to National Park Service (NPS) road crews during the annual spring snow plowing operation. Through a joint collaboration between the NPS and the U.S. Geological Survey (USGS), a forecasting program primarily dealing with wet snow avalanche problems serves to aid worker safety. The objective of this case study is to examine the meteorological metrics and snowpack characteristics leading up to a noteworthy wet slab and glide avalanche cycle that occurred 16-22 April, 2016 during a period of unseasonably warm and sunny weather. Continuous above freezing temperatures at upper elevations with daily maximum values reaching 10-15° C persisted for four days. The nearby Flattop Mountain SNOTEL station reported a steady loss of SWE of approximately 1.25 cm/day. River height and discharge on the Middle Fork of the Flathead River (app. 20-35 km away from starting zones) increased from 1.26 m and 139.60 m3/s (4930 cfs), respectively, on April 18 to 1.69 m and 267.59 m3/s (9450 cfs) on April 22. The ensuing avalanche cycle began with three small glide avalanches on 17 April and culminated in three large wet slab avalanches that released on wet, basal facets. These wet slabs were triggered by glide avalanches releasing above and cascading over cliffs. Four of these avalanches crossed plowed sections of the road, resulting in a three day delay in plowing operations. Finally, this specific case was compared to previous statistical models for wet snow avalanches in this transportation corridor. Out of 12 avalanche days, the model correctly predicted six of those days as avalanche days. This case study allowed for a greater understanding of a wet slab and glide avalanche cycle that occurred during a prolonged spring warming event and can serve as a reference for future similar cycles.

Conference Paper↗

USGS1968

Isotopic analysis of uranium in natural waters by alpha spectrometry

A method is described for the determination of U234/U238 activity ratios for uranium present in natural waters. The uranium is coprecipitated from solution with aluminum phosphate, extracted into ethyl acetate, further purified by ion exchange, and finally electroplated on a titanium disc for counting. The individual isotopes are determined by measurement of the alpha-particle energy spectrum using a high resolution low-background alpha spectrometer. Overall chemical recovery of about 90 percent and a counting efficiency of 25 percent allow analyses of water samples containing as little as 0.10 ?g/l of uranium. The accuracy of the method is limited, on most samples, primarily by counting statistics.

Water Supply Paper↗

USGS2025

White-nose syndrome surveillance and bat monitoring activities in North Coast and Cascades Network parks 2016–2024

Pseudogymnoascus destructans (Pd), the causative agent of white-nose syndrome (WNS) in bats, has caused serious declines in bat populations across North America. We conducted WNS surveillance in five different park units in the North Coast and Cascades Network (NCCN) from 2016 to 2024, following the initial detection of Pd and WNS in Washington State in 2016. We captured and swabbed bats, swabbed roost materials, and collected guano and tested these samples for Pd DNA using qPCR. We confirmed WNS through histopathology of tissue samples and carcasses. We detected Pd at five locations in Mount Rainier National Park, starting in 2017. We confirmed WNS at four of these locations, with the first clinical signs detected in 2022. We detected Pd for the first time in Olympic and North Cascades National Parks in 2024. From these efforts, we generated information that can be compared to other datasets, helping us advance our knowledge of WNS/Pd epidemiology. We also conducted three field and laboratory-based experiments to inform early detection/rapid response (EDRR) planning. The first was a field experiment using non-infective Pd DNA to evaluate the rate of DNA degradation and the probability of detecting Pd DNA in the field. Experimental degradation rates for Pd DNA ranged from 1.6% to 8.2% and were lower in protected sites. The second was a laboratory-based experiment to understand Pd growth on four different substrates. We detected increasing levels of Pd in autoclaved guano and in plywood, suggesting these substrates may be environmental reservoirs. Pd remained stable in fresh guano but in soil it decreased, suggesting microbial interactions that may influence Pd growth in these substrates. We also collected wood shavings from a Pd positive bat box in June and August to evaluate viable Pd persistence in wood in a summer roost. Despite the characterization that Pd required cold conditions to persist, viable Pd was present in wood shavings collected during the summer season. Finally, we evaluated the National White-Nose Syndrome Decontamination Protocol through experiments. We found that ethanol was not effective as a sporicidal agent in any of the concentrations we tested and that a 1:10 dilution of bleach did not kill Pd spores, though higher concentrations did. These findings resulted in changes to the national protocol.

Oregon, Washington↗

USGS2016

Development of working hypotheses linking management of the Missouri River to population dynamics of Scaphirhynchus albus (pallid sturgeon)

This report documents a process of filtering of hypotheses that relate Missouri River Scaphirhynchus albus (pallid sturgeon) population dynamics to management actions including flow alterations, channel reconfigurations, and pallid sturgeon population augmentation. The filtering process was a partnership among U.S. Geological Survey, U.S. Army Corps of Engineers, and U.S. Fish and Wildlife Service to contribute to the Missouri River Recovery Management Plan process. The objective of the filtering process was to produce a set of hypotheses with high relevance to pallid sturgeon population dynamics and decision making on the Missouri River. The Missouri River Pallid Sturgeon Effects Analysis team filtered hundreds of potential hypotheses implicit in conceptual ecological models to develop a set of 40 candidate dominant hypotheses that were identified by experts as being important in pallid sturgeon population dynamics. Using a modified Delphi process and additional expert opinion, the team reduced this set of hypotheses to 23 working dominant hypotheses. We then matched the 23 hypotheses with management actions that could influence the biotic outcomes, resulting in as many as 176 potential effects between management actions and pallid sturgeon in the Missouri River. This number was consolidated to a candidate set of 53 working management hypotheses because some management actions applied to multiple life stages of the pallid sturgeon. We used an additional round of expert surveys to identify a set of 30 working management hypotheses. Finally, the set of working management hypotheses was filtered by the U.S. Army Corps of Engineers, Missouri River Recovery Program for actions that were within the agency’s authority and jurisdiction. This round resulted in a set of 21 hypotheses for initial modeling of linkages from management to pallid sturgeon population responses. The initial set of candidate hypotheses provides a useful starting point for quantitative modeling and adaptive management of the river and species. We anticipate that hypotheses will change from the set of working management hypotheses as adaptive management progresses. More importantly, hypotheses that have been filtered out of our multistep process are still being considered. These filtered hypotheses are archived and if existing hypotheses are determined to be inadequate to explain observed population dynamics, new hypotheses can be created or filtered hypotheses can be reinstated.

Missouri River Basin↗

USGS2006

Physical and vegetative characteristics of a relocated stream reach, constructed wetland, and riparian buffer, Upper Saucon Township, Lehigh County, Pennsylvania, 2000-04

The U.S. Geological Survey, in cooperation with the Pennsylvania Department of Transportation, Engineering District 5-0, investigated physical and vegetative changes within a relocated stream reach, constructed wetland, and riparian buffer from September 2000 to October 2004. This report presents an evaluation of data collected using methods from multiple sources that have been adapted into a consistent approach. This approach is intended to satisfy a need for consistent collection of different types of data with the goal of transferring technology and findings to similar projects. Survey data indicate that adjustment of the upstream part of the relocated stream reach slowed over the monitoring period, but the downstream channel remains unstable as evidenced by excessive deposition. Upstream migration of a nick point has slowed or stopped altogether as of the 2003 assessment when this feature came in contact with the upstream-most part of the channel that is lined with riprap. Documented streambed erosion in the upstream cross sections, along with deposition downstream, has resulted in an overall decrease in slope of the stream channel over the monitoring period. Most streambed erosion took place prior to the 2002 assessment when annual mean streamflows were less than those in the final 2 years of monitoring. An abundance of fine sediment dominates the substrate of the relocated channel. Annual fluctuations of large particles within each cross section demonstrates the capacity of the relocated channel to transport the entire range of sediment. The substrate within the 0.28-acre constructed wetland (a mixture of soil from an off-site naturally occurring wetland and woodchips) supported a hydrophytic-vegetation community throughout the investigation. Eleocharis obtusa (spike rush), an obligate-wetland herb, was the most prevalent species, having a maximum areal cover of 90 percent in fall 2001 and a minimum of 23 percent in fall 2004. Drought-like conditions in water year 2002 (cumulative precipitation was 28.11 inches) allowed species like Panicum dichotomiflorum (witch grass), Salix sp. (willow), Leersia oryzoides (rice cutgrass), and Echinocloa crusgalli (barnyard grass) to become established by fall 2002. Above-average precipitation in water years 2003 and 2004 (58.55 and 53.17 inches, respectively) coincided with increased areal cover by E. obtusa in fall 2003 (56 percent) and decreased areal cover in fall 2004 (23 percent). Pond-like conditions that probably persisted throughout the 2004 growing season favored aquatic species like Alisma subcordatum (water plantain) to the detriment of many emergent species, including E. obtusa. Despite the pond-like conditions, L. oryzoides, an obligate-wetland grass, increased in areal cover (from 12 to 34 percent) between the 2003 and 2004 growing seasons because it was established in the higher elevations and the peripheral areas of the constructed wetland that were less prone to persistent inundation. Canopy development by trees and shrubs in the riparian buffer was initially (fall 2000) poor (39.7 percent), resulting in more available sunlight for the herbaceous understory than in any other growing season. As a result, areal cover of herbaceous species and trees and shrubs less than 1-meter tall was 108 percent in fall 2000 with Lolium perenne (perennial rye), Polygonum persicaria (lady's thumb), and Setaria faberi (foxtail) collectively contributing nearly half the cover (59.2 percent). Because of increases in canopy cover by trees and shrubs (39.7 percent in fall 2000 to 127 percent in fall 2004), herbaceous cover decreased to 76 percent by the fall of 2001 and varied between 72 and 77 percent for the rest of the study period. Tree density in the riparian buffer ranged from 3,078 and 4,130 plants per acre (fall 2000 and 2003, respectively) over the study period but essentially remained constant after fall 2001; computations reported each fall between fall 2001 and fall 2004 are within 10 percent of one another. When the study ended in fall 2004, Acer negundo (box elder) and Fraxinus pennsylvanica (green ash) were the most populous tree species (1,526 and 1,084 plants per acre, respectively) followed by Quercus bicolor (swamp white oak; 720 plants per acre). A. negundo , F. pennsylvanica , and Q. bicolor also contributed the greatest areal cover in fall 2004 (31.2, 24.0, and 18.5 percent,respectively).

Pennsylvania↗

USGS2025

Tracking status and trends in seven key indicators of river and stream condition in the Chesapeake Bay watershed

Freshwater streams and rivers are recognized as vital habitats within the Chesapeake Bay watershed, which has been undergoing extensive restoration efforts for more than 30 years. Resource managers need to understand stream and river condition and how these conditions are changing over time to determine whether regional long-term restoration and conservation goals are being met. The objective of this report was to document the spatial and temporal variability of conditions for seven indicators of river and stream health across the nontidal Chesapeake Bay watershed. The framework for the U.S. Geological Survey’s Nontidal Network (NTN), a network of more than 100 nutrient and suspended sediment monitoring locations, was extended to assess conditions for six additional indicators of stream health: temperature, salinity, toxic contaminants, streamflow, hydromorphology, and biological aquatic communities. For each indicator, the latest available data from multiple sources were compiled and harmonized, and key metrics were identified to describe indicator conditions across space and time. A status condition was defined for each indicator to describe overall spatial variability in recent condition, and trend analyses were used to describe changes in each indicator metric over time. The analysis revealed clear differences in spatial and temporal data coverage across the seven indicators, so individual indicator trend analyses were not constrained to a common time interval. However, a status snapshot was conducted across all indicators for the 2015–17 period to simultaneously explore spatial variability across all indicators. The status snapshot highlighted general degraded conditions across multiple indicators in large metropolitan regions, such as the Baltimore–Washington, D.C., metropolitan area. Regression analysis between indicator status metrics and major land cover for the sites suggest urbanization as a potential driver of degraded conditions for many of the indicator metrics, including total phosphorus, salinity, temperature, high-flow frequency, and metrics of habitat and biological assemblage quality. A final analysis exploring the spatial representation of each indicator network showed that some indicator monitoring networks did not cover certain settings, such as small watersheds. These results provided an initial assessment of stream health status and trends and will continue to be leveraged to describe conditions across the Chesapeake Bay watershed to help inform local and regional management decisions. These results also highlighted the need for improved coordination among monitoring organizations to support long-term multi-indicator monitoring and assessment.

Chesapeake Bay watershed↗

USGS1990

Partitioning of F between H2O and CO2 fluids and topaz rhyolite melt - Implications for mineralizing magmatic-hydrothermal fluids in F-rich granitic systems

Fluid/melt distribution coefficients for F have been determined in experiments conducted with peraluminous topaz rhyolite melts and fluids consisting of H2O and H2O+CO2 at pressures of 0.5 to 5 kbar, temperatures of 775??-1000??C, and concentrations of F in the melt ranging from 0.5 to 6.9 wt%. The major element, F, and Cl concentrations of the starting material and run product glasses were determined by electron microprobe, and the concentration of F in the fluid was calculated by mass balance. The H2O concentrations of some run product glasses were determined by ion microprobe (SIMS). The solubility of melt in the fluid phase increases with increasing F in the system; the solubility of H2O in the melt is independent of the F concentration of the system with up to 6.3 wt% F in the melt. No evidence of immiscible silica- and fluoriderich liquids was detected in the hydrous but water-undersaturated starting material glasses (???8.5 wt% F in melt) or in the water-saturated run product glasses. F concentrates in topaz rhyolite melts relative to coexisting fluids at most conditions studied; however, DF (wt% F in fluid/wt% F in melt) increases strongly with increasing F in the system. Maximum values of DF in this study are significantly larger than those previously reported in the literature. Linear extrapolation of the data suggests that DF is greater than one for water-saturated, peraluminous granitic melts containing ???8 wt% F at 800?? C and 2 kbar. DF increases as temperature and as (H2O/H2O+CO2) of the fluid increase. For topaz rhyolite melts containing ???1 wt% F and with H2O-rich fluids, DF is independent of changes in pressure from 2 to 5 kbar at 800?? C; for melts containing ???1 wt% F and in equilibrium with CO2-bearing fluids the concentrations of F in fluid increases with increasing pressure. F-and lithophile element-enriched granites may evolve to compositions containing extreme concentrations of F during the final stages of crystallization. If F in the melt exceeds 8 wt%, DF is greater than one and the associated magmatic-hydrothermal fluid contains >4 molal F. Such F-enriched fluids may be important in the mass transport of ore constituents, i.e., F, Mo, W, Sn, Li, Be, Rb, Cs, U, Th, Nb, Ta, and B, from the magma. ?? 1990 Springer-Verlag.

Contributions to Mineralogy and Petrology↗

USGS2026

Evaluating machine learning approaches to identify and predict oil and gas produced water lithium concentrations

Recently, the demand for battery-grade lithium has substantially increased, largely due to electrification of the transportation sector. The search for new lithium sources has turned to produced waters (frequently brines), a large-volume wastewater by-product of oil and gas extraction. Geochemical analysis indicates the presence of varying concentrations of lithium from produced water samples collected across the United States and represented in the U.S. Geological Survey’s National Produced Water Geochemical Database, as well as mixtures of Marcellus Shale produced water included in the Pennsylvania Department of Environmental Protection’s Oil and Gas Well Waste Reports. We first examined whether the geochemical signature of the lithium-bearing produced waters is sufficiently distinct so that machine learning (ML) can be used to correctly classify samples to the formation of origin. The produced water sample data used to assess classification accuracy were from the Marcellus Shale, Utica Shale and Point Pleasant Formation (Utica), and Smackover Formation oil and gas wells. Further, we evaluated the potential for ML to accurately classify Marcellus Shale produced water spatially (i.e., northeast versus southwest Pennsylvania). We then investigated whether ML algorithms applied to a suite of geochemical concentration data (i.e. Ba, Br, Cl, K, Mg, Sr) may be used to predict the lithium concentration of an unknown sample. Finally, we applied an estimated economic lithium grade cutoff of 150 milligrams per liter (mg/l) and assessed the utility of ML to predict whether a produced water sample would fall above or below the grade cutoff based on the suite of geochemical parameters. Four machine learning algorithms—Random Forest (RF), Gradient Boosting Trees (GBT), Extreme Boosting (XGBoost), and Deep Neural Networks (DNN) were assessed. This study successfully demonstrates that all four machine learning methods can precisely and accurately estimate lithium concentrations and geologic formation classification. The products of this study contribute to the growing body of knowledge aimed at expanding the lithium resource base within the United States.

Alabama, Arkansas, Florida, Georgia, Louisiana, Mi↗

USGS2026

Using organic compounds and salt mixtures to investigate potential mechanisms of major ion toxicity to the mayfly Neocloeon triangulifer

Field assessments and laboratory studies have demonstrated that mayflies (Ephemeroptera) are relatively sensitive to increased concentrations of major geochemical ions (Na + , Ca 2+ , Mg 2+ , K + , Cl − , SO 4 2− , HCO 3 − /CO 3 2- ), but much remains to be learned about potential mechanisms of toxicity. In the present study, we sought to determine whether solution osmolarity is sufficient to predict the toxic effects of major ions to a mayfly, Neocloeon triangulifer . We further investigated whether binary mixtures of major ion salts with common cations or common anions provide evidence of concentration addition or independent action, potentially illuminating toxicity drivers for this species. Finally, we sought to determine if there are mechanisms for major ion toxicity to mayflies that are comparable to those for other species. The toxicity of single salts showed a Ca-dependent correlation with the total component concentration (the sum of individual ion concentrations, a close correlate of osmolarity), but the effect concentrations were well below those causing toxicity from mannitol (presumed to have only an osmotic effect), suggesting that a general osmotic effect is not responsible for major ion toxicity in this species. The mixture experiments consistently indicated additive toxicity and consistency with the relationship to total component concentration, which supports a single toxic mechanism and thus no evidence for ion-specific mechanisms, as reported for other species. Given the lack of evidence of ion-specific toxicity, the total component metric is likely useful for a broad range of ionic compositions.

Environmental Toxicology and Chemistry↗