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USGS1990

Hydrogeology of the Cliff House Sandstone in the San Juan structural basin, New Mexico, Colorado, Arizona, and Utah

This report is one in a series resulting from the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) study of the San Juan structural basin that began in October 1984. Previous reports in the series describe the hydrogeology of the Dakota Sandstone (Craigg and others, 1989), Point Lookout Sandstone (Craigg and others, 1990), Morrison Formation (Dam and others, 1990), Gallup Sandstone (Kernodle and others, 1989), and Menefee Formation (Levings and others, 1990) in the San Juan structural basin. The purposes of the RASA (Welder, 1986) are to: (1) Define and evaluate the aquifer system; (2) assess the effects of past, present, and potential ground-water use on aquifers and streams; and (3) determine the availability and quality of ground water. This report summarizes information on the geology and the occurrence and quality of water in the Cliff House Sandstone, one of the primary water-bearing units in the regional aquifer system. Data used in this report were collected during the study or were derived from existing records in the U.S. Geological Survey's computerized National Water Information System (NWIS) data base, the Petroleum Information Corporation's data base, and the Dwight's ENERGYDATA Inc. BRIN data base. Although all data available for the Cliff House Sandstone were considered in formulating the discussions in the text, not all those data could be plotted on the illustrations. The San Juan structural basin is in New Mexico, Colorado, Arizona, and Utah and has an area of about 21,600 square miles (fig. 1). The structural basin is about 140 miles wide and about 200 miles long. The study area is that part of the structural basin that contains rocks of Triassic or younger age and, therefore, is less extensive than the structural basin. Triassic through Tertiary sedimentary rocks are emphasized in this study because the major aquifers in the basin are present in these rocks. The study area is about 140 miles wide (about the same as the structural basin), 180 miles long, and has an area of about 19,400 square miles. Altitudes in the study area range from about 4,500 feet in San Juan County, Utah, to about 11,000 feet in Cibola County, New Mexico. Annual precipitation in the high mountainous areas along the north and east margins of the basin is as much as 45 inches, whereas annual precipitation in the lower altitude, central basin is generally less than 8 inches. Mean annual precipitation in the study area is about 12 inches. Data obtained from documents published by the U.S. Bureau of the Census, 1980 and 1985, were used to estimate the population of the study area. The population of the study area in 1970 was estimated to be about 134,000. The population rose to about 194,000 in 1980, 212,000 in 1982, 221,000 in 1984, and then fell to about 210,000 in 1985. The economy of the basin is supported by exploration and development of petroleum, natural gas, coal, and uranium resources; urban enterprise, farming and ranching; tourism; and recreation. The rise and fall in population were related to changes in the economic strength of the mining, petroleum, and natural-gas industries, and support services. Uranium mining and milling activities grew rapidly until the late 1970's when most uranium-mining activity ended in the study area. Likewise, the oil and gas industry prospered until about 1983 and then declined rapidly, also affecting many jobs in support industries.

Arizona, Colorado, New Mexico, Utah↗

USGS1990

Hydrogeology of the Point Lookout Sandstone in the San Juan structural basin, New Mexico, Colorado, Arizona, and Utah

This report is one in a series resulting from the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) study of the San Juan structural basin that began in October 1984. Previous reports in the series describe the hydrogeology of the Dakota Sandstone (Craigg and others, 1989), Morrison Formation (Dam and others, 1990), Gallup Sandstone (Kernodle and others, 1989), Menefee Formation (Levings and others, 1990), and Cliff House Sandstone (Thorn and others, 1990), in the San Juan structural basin. The purposes of the RASA (Welder, 1986) are to: (1) Define and evaluate the aquifer system; (2) assess the effects of past, present, and potential ground-water use on aquifers and streams; and (3) determine the availability and quality of ground water. This report summarizes information on the geology and the occurrence and quality of water in the Point Lookout Sandstone, one of the primary water-bearing units in the regional aquifer system. Data used in this report were collected during the study or were derived from existing records in the U.S. Geological Survey's computerized National Water Information System (NWIS) data base, the Petroleum Information Corporation's database, and the Dwight's ENERGYDATA Inc. BRIN data base. Although all data available for the Point Lookout Sandstone were considered in formulating the discussions in the text, not all those data could be plotted on the illustrations. The San Juan structural basin is in New Mexico, Colorado, Arizona, and Utah and has an area of about 21,600 square miles (fig. 1). The structural basin is about 140 miles wide and about 200 miles long. The study area is that part of the structural basin that contains rocks of Triassic or younger age and, therefore, is less areally extensive than the structural basin. Triassic through Tertiary sedimentary rocks are emphasized in this study because the major aquifers in the basin are present in these rocks. The study area is about 140 miles wide (about the same as the structural basin), 180 miles long, and has an area of about 19,400 square miles. Altitudes in the study area range from about 4,500 feet in San Juan County, Utah, to about 11,000 feet in Cibola County, New Mexico. Annual precipitation in the high mountainous areas along the north and east margins of the basin is as much as 45 inches, whereas annual precipitation in the lower altitude, central basin is generally less than 8 inches. Mean annual precipitation in the study area is about 12 inches. Data obtained from documents published by the U.S. Bureau of the Census, 1980 and 1985, were used to estimate the population of the study area. The population of the study area in 1970 was estimated to be about 134,000. The population rose to about 194,000 in 1980, 212,000 in 1982, 221,000 in 1984, and then fell to about 210,000 in 1985. The economy of the basin is supported by exploration and development of petroleum, natural gas, coal, and uranium resources; urban enterprise, farming "and ranching; tourism; and recreation. The rise and fall in population were related to changes in the economic strength of the mining, petroleum, and natural-gas industries, and support services. Uranium mining and milling activities grew rapidly until the late 1970's when most uranium-mining activity ended in the study area. Likewise, the oil and gas industry prospered until about 1983 and then declined rapidly, also affecting many jobs in support industries.

Arizona, Colorado, New Mexico, Utah↗

USGS2014

Mercury in the nation's streams - Levels, trends, and implications

Mercury is a potent neurotoxin that accumulates in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury originates from combustion of coal and can travel long distances in the atmosphere before being deposited. This can result in mercury-contaminated fish in areas with no obvious source of mercury pollution. Three key factors determine the level of mercury contamination in fish - the amount of inorganic mercury available to an ecosystem, the conversion of inorganic mercury to methylmercury, and the bioaccumulation of methylmercury through the food web. Inorganic mercury originates from both natural sources (such as volcanoes, geologic deposits of mercury, geothermal springs, and volatilization from the ocean) and anthropogenic sources (such as coal combustion, mining, and use of mercury in products and industrial processes). Humans have doubled the amount of inorganic mercury in the global atmosphere since pre-industrial times, with substantially greater increases occurring at locations closer to major urban areas. In aquatic ecosystems, some inorganic mercury is converted to methylmercury, the form that ultimately accumulates in fish. The rate of mercury methylation, thus the amount of methylmercury produced, varies greatly in time and space, and depends on numerous environmental factors, including temperature and the amounts of oxygen, organic matter, and sulfate that are present. Methylmercury enters aquatic food webs when it is taken up from water by algae and other microorganisms. Methylmercury concentrations increase with successively higher trophic levels in the food web—a process known as bioaccumulation. In general, fish at the top of the food web consume other fish and tend to accumulate the highest methylmercury concentrations. This report summarizes selected stream studies conducted by the U.S. Geological Survey (USGS) since the late 1990s, while also drawing on scientific literature and datasets from other sources. Previous national mercury assessments by other agencies have focused largely on lakes. Although numerous studies of mercury in streams have been conducted at local and regional scales, recent USGS studies provide the most comprehensive, multimedia assessment of streams across the United States, and yield insights about the importance of watershed characteristics relative to mercury inputs. Information from other environments (lakes, wetlands, soil, atmosphere, glacial ice) also is summarized to help understand how mercury varies in space and time.

Circular↗

USGS2023

Assessment of riparian vegetation patterns and change downstream from Glen Canyon Dam from 2014 to 2019

Changes in riparian vegetation cover and composition occur in relation to flow regime, geomorphic template, and climate, and can have cascading effects on aquatic and terrestrial ecosystems. Tracking such changes over time is therefore an important part of monitoring the condition and trajectory of riparian ecosystems. Maintaining diverse, self-sustaining riparian vegetation comprised of mostly native species is identified in the Glen Canyon Dam Long-Term Experimental and Management Plan as a key resource objective for the section of the Colorado River between Glen Canyon Dam and Lake Mead. The U.S. Geological Survey Grand Canyon Monitoring and Research Center implemented an annual monitoring program in 2014 to assess the status and trends of riparian vegetation along this section of river, particularly as they relate to flow regime. In this report, we summarize plant species composition and cover data collected under the annual monitoring program from 2014 to 2019, with special consideration given to the hydrologic position, associated geomorphic feature class, local climate patterns, native and nonnative species, and floristic region for key vegetation metrics and species. We divided the study area into four river segments (referred to as Glen Canyon, Marble Canyon, eastern Grand Canyon, and western Grand Canyon) on the basis of geography and floristic composition and calculated each recorded plant species’ relative frequency and foliar cover by river segment. These data were then used to evaluate species composition relationships among river segments, hydrologic zones, geomorphic features, and sampling years through ordination analysis. Temporal trends in our focal resource objectives—species richness, total foliar cover, proportion of native to nonnative species richness, proportion of native to nonnative species cover, Tamarix cover, Pluchea sericea cover, and Baccharis species cover—were assessed using mixed-effects models. Four patterns related to species composition emerged: (1) species composition of fixed-site sandbars differed from that of randomly selected sites (including randomly selected sandbars), (2) species composition of Glen Canyon sites differed from that of other previously identified floristic regions, (3) species composition differed across hydrologic zones related to dam operations, and (4) species composition within river segments did not change across years. For temporal patterns, four main findings emerged: (1) trends differed between fixed-sites and randomly selected sites; (2) although few directional changes were observed from 2014 to 2019, Baccharis species cover increased at randomly selected sites in areas influenced by daily water fluctuations; (3) native species cover and richness were greater than nonnative species cover and richness across all hydrologic zones; and (4) the temporal trend metrics used here can be used across floristic groups, enabling assessment of the Colorado River ecosystem as a whole. In addition to these findings, lists of recorded plant species are included as appendixes. The variations and patterns in vegetation status and trends presented in this report can be used as a baseline against which future monitoring can be compared.

Arizona↗

USGS2021

Capacity assessment for Earth Monitoring, Analysis, and Prediction (EarthMAP) and future integrated monitoring and predictive science at the U.S. Geological Survey

Executive Summary Managers of our Nation’s resources face unprecedented challenges driven by the convergence of increasing, competing societal demands and a changing climate that affects the stability, vulnerability, and predictability of those resources. To help meet these challenges, the scientific community must take advantage of all available technologies, data, and integrative Earth systems modeling capacity to better inform resource and risk management decisions. This is the overarching goal of the U.S. Geological Survey (USGS) Earth Monitoring, Analysis, and Prediction (EarthMAP) vision: “By 2030, the USGS will deliver well integrated observations and predictions of the future state of natural systems—water, ecosystems, energy, minerals, hazards—at regional and national scales, working primarily with federal, state, and academic partners to develop and operate the capability” (U.S. Geological Survey, 2021). Providing more integrated Earth systems science and actionable information to decision makers, stakeholders, and the public requires a better understanding of the depth and distribution of existing capacity (capabilities, tools, and techniques) across the Bureau. Identifying existing capacity is also a critical first step toward gap analysis and targeted investments to increase capacity over time. The USGS formed a Capacity Assessment Team (CAT) and charged it with (1) conducting a Request for Information (RFI) to identify existing USGS expertise and activities supportive of integrated and predictive science to inform decision making, (2) developing a strategy and proof-of-concept for a continuously updated capacity assessment capability, and (3) identifying lessons learned to inform development of best practices for future capacity assessment efforts. The RFI took the form of a survey, with content guided by the science and technology needs identified in a USGS report titled “Grand Challenges for Integrated U.S. Geological Survey Science—A Workshop Report” (Jenni and others, 2017). The 44-question survey provided respondents the ability to rate their level of experience with a suite of priority disciplines, analysis and modeling approaches, technologies, and stakeholder engagement strategies and to enter optional narrative text for supporting context. An introductory portion focused on general science capacity assessment, followed by three sections targeting capabilities related to the foundational components of EarthMAP: (1) data and information integration, (2) integrated predictive science, and (3) actionable information. The survey results provided a high-level snapshot of USGS capacity in the targeted areas. Respondents (1,035 individuals) represented approximately 13 percent of the USGS across all mission areas and regions. Seventy-four percent of the respondents held a science-focused position title and the remainder had position titles in information technology, computer science, management, administrative, or other (contractors, volunteers, emeritus, and unknown). To provide greater insight into respondent capabilities and activities, information from the U.S. Department of the Interior and USGS enterprise information systems were used to further characterize topical expertise and organizational associations of survey respondents. To address the ongoing need to assess the Bureau’s capacity to address integrated predictive science priorities, the CAT developed a software-based proof-of-concept called the Integrated Science Assessment Information Database (iSAID) for assembling various information sources together toward making the full extent of USGS capabilities and scientific assets available for routine capacity assessment. This proof-of-concept is intended to serve as a catalyst for further development. The process of implementing the EarthMAP capacity assessment survey, analyzing survey responses, and developing the proof-of-concept resulted in lessons learned, findings, and recommendations. Example scenarios throughout the report demonstrate how capacity assessment data can inform science planning. Three overarching findings and recommendations are: (1) Finding: Capacity is limited in some critical disciplines, skills, and technology applications, but “sufficient” depends on the question and the need relative to availability at a given point in time. Recommendation: Develop an on-demand capacity assessment framework that enables rapid identification and evaluation of existing and available expertise to support decision needs as they arise. (2) Finding: Institutional barriers and lack of awareness constrain the ability of USGS staff to adopt new technologies, collaborate across administrative boundaries, and deliver actionable information to stakeholders in a timely manner. However, these barriers are not universally experienced. Recommendation: Pursue more targeted inquiries to clarify which institutional barriers are obstructing the adoption of new technologies and approaches or the sharing of expertise and equipment across organizational and regional boundaries. These inquiries should inform USGS leadership, mission areas, and regions whether policies can be revised or whether a lack of understanding is creating perceived obstacles. Highlight cases when staff have successfully adopted new technologies and approaches to advance EarthMAP priorities and provide actionable information in a timely manner to spread awareness of how perceived obstacles can be navigated and overcome when appropriate. (3) Finding: Examples of people and projects integrating across disciplines and scales and applying advanced approaches to meet complex stakeholder needs exist. Such examples provide transfer value across the spectrum from approach to decision making. Many projects, already underway, appear to meet elements of the EarthMAP vision, and the USGS has people who can provide leadership in multiple types of specific integrated science efforts. Recommendation: Use these findings as a starting point for near-term strategic planning for integrated science. Highlight, incentivize, and build on existing interdisciplinary predictive science and information delivery activities across the USGS to advance toward further realization of an EarthMAP capacity. The CAT efforts to develop and assess existing USGS capacity to advance the EarthMAP vision revealed a fundamental challenge for not only this effort but any effort to assess existing capacity: A considerable amount of thought, time, and effort is required to survey and assess capabilities and tools available to support a given need, yet best results are still likely to provide an incomplete assessment. To better meet the frequent need to assess capabilities, tools, products, and projects that address an expressed strategic priority, the CAT proposes the concept of an on-demand capacity assessment framework supported by a software package that dynamically pulls and integrates information from existing USGS information systems and public domain registries. Although existing USGS enterprise information systems currently lack the structure, cross-system consistency, interoperability, and stability to support a continuously updated capacity assessment capability, we identify reasonable near-term steps to improve the utility of information gathered on expertise and project capacity and to improve the consistency and completeness of information and the ability of USGS systems to share that information. The ability to search and characterize this information will make future assessments of capacity faster, more complete, more efficient, and more targeted. This approach would grow the Bureau’s capacity knowledge over time, iteratively improving the ability to access, leverage, and synthesize existing capabilities and assets as well as identify and fill critical gaps. The greatest promise for developing integrated science could lie in linking across existing projects and expertise to create a multi-project capacity for addressing large, complex environmental issues.

Open-File Report↗

USGS2026

A three-dimensional geologic framework model of the northern Great Plains region of Montana, North Dakota, South Dakota, and Wyoming, USA

This report presents a new three-dimensional geologic framework model (GFM) of the northern Great Plains region, encompassing parts of Montana, North Dakota, South Dakota, and Wyoming. The model provides a regionally consistent, geographic information system (GIS)-ready representation of Phanerozoic sedimentary strata, major fault systems, and Precambrian basement geometry across two sedimentary basins and adjacent uplifts. More than 300,000 geologic and geophysical data inputs were synthesized to model 41 stratigraphic horizons and 47 faults, yielding an internally coherent, sealed-volume interpretation of the subsurface. The modeling workflow developed for this study demonstrates an efficient and scalable approach for constructing basin-to regional-scale GFMs in geologically complex and data-variable settings. Although model fidelity varies with data density and quality, the resulting geometry is broadly consistent with 1:500,000-scale geologic mapping and highlights areas where additional geologic study is most needed. The three-dimensional GFM provides a foundational framework to support groundwater, energy, and mineral resource assessments, and offers a transferable methodology for potential future U.S. Geological Survey efforts to build large-area subsurface models in underexplored regions of the United States.

Montana, North Dakota, South Dakota, Wyoming↗

USGS1995

Pesticides in the atmosphere–Current understanding of distribution and major influences

This report summarizes a comprehensive analysis of existing information on national and regional patterns of pesticides in the atmosphere and major influences on their sources and transport. It is one of a four-part series that synthesizes current knowledge and understanding of pesticides in water resources of the nation as part of the National Water-Quality Assessment.

Fact Sheet↗

USGS1996

Pesticides in ground water: Current understanding of distribution and major influences

Fact Sheet↗

USGS2016

Late Pleistocene and Holocene tephrostratigraphy of interior Alaska and Yukon: Key beds and chronologies over the past 30,000 years

The Aleutian Arc-Alaska Peninsula and Wrangell volcanic field are the main source areas for tephra deposits found across Alaska and northern Canada, and increasingly, tephra from these eruptions have been found further afield in North America, Greenland, and Europe. However, there have been no broad scale reviews of the Late Pleistocene and Holocene tephrostratigraphy for this region since the 1980s, and this lack of data is hindering progress in identifying these tephra both locally and regionally. To address this gap and the variable quality of associated geochemical and chronological data, we undertake a detailed review of the latest Pleistocene to Holocene tephra found in interior Alaska and Yukon. This paper discusses nineteen tephra that have distributions beyond southwest Alaska and that have the potential to become, or already are, important regional markers. This includes three ‘modern’ events from the 20th century, ten with limited data availability but potentially broad distributions, and six that are widely reported in interior Alaska and Yukon. Each tephra is assessed in terms of chronology, geochemistry and distribution, with new Bayesian age estimates and geochemical data when possible. This includes new major-element geochemical data for Crater Peak 1992, Redoubt 1989–90, and two andesitic tephra from St Michael Island (Tephra D), as well as revised age estimates for Dawson tephra, Oshetna, Hayes set H, Aniakchak CFE II, and the White River Ashes, northern and eastern lobes.

Quaternary Science Reviews↗

USGS2007

Undiscovered locatable mineral resources in the Bay Resource Management Plan Area, southwestern Alaska: A probabilistic assessment

The Bay Resource Management Plan (RMP) area in southwestern Alaska, north and northeast of Bristol Bay contains significant potential for undiscovered locatable mineral resources of base and precious metals, in addition to metallic mineral deposits that are already known. A quantitative probabilistic assessment has identified 24 tracts of land that are permissive for 17 mineral deposit model types likely to be explored for within the next 15 years in this region. Commodities we discuss in this report that have potential to occur in the Bay RMP area are Ag, Au, Cr, Cu, Fe, Hg, Mo, Pb, Sn, W, Zn, and platinum-group elements. Geoscience data for the region are sufficient to make quantitative estimates of the number of undiscovered deposits only for porphyry copper, epithermal vein, copper skarn, iron skarn, hot-spring mercury, placer gold, and placer platinum-deposit models. A description of a group of shallow- to intermediate-level intrusion-related gold deposits is combined with grade and tonnage data from 13 deposits of this type to provide a quantitative estimate of undiscovered deposits of this new type. We estimate that significant resources of Ag, Au, Cu, Fe, Hg, Mo, Pb, and Pt occur in the Bay Resource Management Plan area in these deposit types. At the 10th percentile probability level, the Bay RMP area is estimated to contain 10,067 metric tons silver, 1,485 metric tons gold, 12.66 million metric tons copper, 560 million metric tons iron, 8,100 metric tons mercury, 500,000 metric tons molybdenum, 150 metric tons lead, and 17 metric tons of platinum in undiscovered deposits of the eight quantified deposit types. At the 90th percentile probability level, the Bay RMP area is estimated to contain 89 metric tons silver, 14 metric tons gold, 911,215 metric tons copper, 330,000 metric tons iron, 1 metric ton mercury, 8,600 metric tons molybdenum and 1 metric ton platinum in undiscovered deposits of the eight deposit types. Other commodities, which may occur in the Bay RMP area, include Cr, Sn, W, Zn, and other platinum-group elements such as Ir, Os, and Pd. We define 13 permissive tracts for 9 additional deposit model types. These are: Besshi- and Cyprus, and Kuroko-volcanogenic massive sulfides, hot spring gold, low sulfide gold veins, Mississippi-Valley Pb-Zn, tin greisen, zinc skarn and Alaskan-type zoned ultramafic platinum-group element deposits. Resources in undiscovered deposits of these nine types have not been quantified, and would be in addition to those in known deposits and the undiscovered resources listed above. Additional mineral resources also may occur in the Bay RMP area in deposit types, which were not considered here.

Alaska↗

USGS2008

Geologic map of the Camas Quadrangle, Clark County, Washington, and Multnomah County, Oregon

The Camas 7.5' quadrangle is in southwestern Washington and northwestern Oregon approximately 20 km east of Portland. The map area, bisected by the Columbia River, lies on the eastern margin of the Portland Basin, which is part of the Puget-Willamette Lowland that separates the Cascade Range from the Oregon Coast Range. Since late Eocene time, the Cascade Range has been the locus of an episodically active volcanic arc associated with underthrusting of oceanic lithosphere beneath the North American continent along the Cascadia Subduction Zone. Bedrock consists largely of basalt and basaltic andesite flows that erupted during late Oligocene time from one or more vents located outside the map area. These rocks crop out only north of the Columbia River: at the base of Prune Hill in Camas, where they dip southward at about 5°; and east of Lacamas Creek, where they dip to the southeast at 15 to 30°. The volcanic bedrock is unconformably overlain by Neogene sediments that accumulated as the Portland Basin subsided. In the Camas quadrangle, most of these sediments consist of basaltic hyaloclastic debris generated in the volcanic arc to the east and carried into the Portland Basin by the ancestral Columbia River. The dominant structures in the map area are northwest-striking dextral strike-slip faults that offset the Paleogene basin floor as well as the lower part of the basin fill. The Oligocene rocks at Prune Hill and to the east were uplifted in late Pliocene to early Pleistocene time within a restraining bend along one of these dextral faults. In Pleistocene time, basaltic andesite flows issued from a volcano centered on the west side of Prune Hill; another flow entered the map area from the east. These flows are part of the Boring volcanic field, which comprises several dozen late Pliocene and younger monogenetic volcanoes scattered throughout the greater Portland region. In latest Pleistocene time, the Missoula floods of glacial-outburst origin inundated the Portland Basin. The floods deposited huge bars of poorly sorted gravel in the lee of Prune Hill and west of the Sandy River. Volcanic debris from Mount Hood form a prominent delta at the mouth of the Sandy River. This map is a contribution to a program designed to improve geologic knowledge of the Portland Basin region of the Pacific Northwest urban corridor, the densely populated Cascadia forearc region of western Washington and Oregon. More detailed information on the bedrock and surficial geology of the basin and its surrounding area is necessary to refine assessments of seismic risk, ground-failure hazards and resource availability in this rapidly growing region.

Oregon, Washington↗

USGS1998

Analysis of ground-water-quality data of the Upper Colorado River basin, water years 1972-92

As part of the U.S. Geological Survey's National Water-Quality Assessment program, an analysis of the existing ground-water-quality data in the Upper Colorado River Basin study unit is necessary to provide information on the historic water-quality conditions. Analysis of the historical data provides information on the availability or lack of data and water-quality issues. The information gathered from the historical data will be used in the design of ground-water-quality studies in the basin. This report includes an analysis of the ground-water data (well and spring data) available for the Upper Colorado River Basin study unit from water years 1972 to 1992 for major cations and anions, metals and selected trace elements, and nutrients. The data used in the analysis of the ground-water quality in the Upper Colorado River Basin study unit were predominantly from the U.S. Geological Survey National Water Information System and the Colorado Department of Public Health and Environment data bases. A total of 212 sites representing alluvial aquifers and 187 sites representing bedrock aquifers were used in the analysis. The available data were not ideal for conducting a comprehensive basinwide water-quality assessment because of lack of sufficient geographical coverage. Evaluation of the ground-water data in the Upper Colorado River Basin study unit was based on the regional environmental setting, which describes the natural and human factors that can affect the water quality. In this report, the ground-water-quality information is evaluated on the basis of aquifers or potential aquifers (alluvial, Green River Formation, Mesaverde Group, Mancos Shale, Dakota Sandstone, Morrison Formation, Entrada Sandstone, Leadville Limestone, and Precambrian) and land-use classifications for alluvial aquifers. Most of the ground-water-quality data in the study unit were for major cations and anions and dissolved-solids concentrations. The aquifer with the highest median concentrations of major ions was the Mancos Shale. The U.S. Environmental Protection Agency secondary maximum contaminant level of 500 milligrams per liter for dissolved solids in drinking water was exceeded in about 75 percent of the samples from the Mancos Shale aquifer. The guideline by the Food and Agriculture Organization of the United States for irrigation water of 2,000 milligrams per liter was also exceeded by the median concentration from the Mancos Shale aquifer. For sulfate, the U.S. Environmental Protection Agency proposed maximum contaminant level of 500 milligrams per liter for drinking water was exceeded by the median concentration for the Mancos Shale aquifer. A total of 66 percent of the sites in the Mancos Shale aquifer exceeded the proposed maximum contaminant level. Metal and selected trace-element data were available for some sites, but most of these data also were below the detection limit. The median concentrations for iron for the selected aquifers and land-use classifications were below the U.S. Environmental Protection Agency secondary maximum contaminant level of 300 micrograms per liter in drinking water. Median concentration of manganese for the Mancos Shale exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 50 micrograms per liter in drinking water. The highest selenium concentrations were in the alluvial aquifer and were associated with rangeland. However, about 22 percent of the selenium values from the Mancos Shale exceeded the U.S. Environmental Protection Agency maximum contaminant level of 50 micrograms per liter in drinking water. Few nutrient data were available for the study unit. The only nutrient species presented in this report were nitrate-plus-nitrite as nitrogen and orthophosphate. Median concentrations for nitrate-plus-nitrite as nitrogen were below the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter in drinking water except for 0.02 percent of the sites in the alluvial aquifer and 0.03 percent of the sites in the Mancos Shale. Concentrations of orthophosphate did not vary significantly among aquifers or land-use classifications. Historic water-quality data from wells and springs helped to characterize the regional distribution of ground-water quality information in the Upper Colorado River Basin study unit. The historical ground-water data summarized in this report will be used in the design of a ground-water-quality network. Because ground-water-quality issues in the study unit are related to high dissolved solids, sulfate, selenium, and nutrients, this report discusses some of the important findings related to these issues.

Colorado↗

USGS2013

Prioritization of constituents for national- and regional-scale ambient monitoring of water and sediment in the United States

A total of 2,541 constituents were evaluated and prioritized for national- and regional-scale ambient monitoring of water and sediment in the United States. This prioritization was done by the U.S. Geological Survey (USGS) in preparation for the upcoming third decade (Cycle 3; 2013–23) of the National Water-Quality Assessment (NAWQA) Program. This report provides the methods used to prioritize the constituents and the results of that prioritization. Constituents were prioritized by the NAWQA National Target Analyte Strategy (NTAS) work group on the basis of available information on physical and chemical properties, observed or predicted environmental occurrence and fate, and observed or anticipated adverse effects on human health or aquatic life. Constituents were evaluated within constituent groups that were determined on the basis of physical or chemical properties or on uses or sources. Some constituents were evaluated within more than one constituent group. Although comparable objectives were used in the prioritization of constituents within the different constituent groups, differences in the availability of information accessed for each constituent group led to the development of separate prioritization approaches adapted to each constituent group to make best use of available resources. Constituents were assigned to one of three prioritization tiers: Tier 1, those having the highest priority for inclusion in ambient monitoring of water or sediment on a national or regional scale (including NAWQA Cycle 3 monitoring) on the basis of their likelihood of environmental occurrence in ambient water or sediment, or likelihood of effects on human health or aquatic life; Tier 2, those having intermediate priority for monitoring on the basis of their lower likelihood of environmental occurrence or lower likelihood of effects on human health or aquatic life; and Tier 3, those having low or no priority for monitoring on the basis of evidence of nonoccurrence or lack of effects on human health or aquatic life, or of having insufficient evidence of potential occurrence or effects to justify placement into Tier 2. Of the 1,081 constituents determined to be of highest priority for ambient monitoring (Tier 1), 602 were identified for water and 686 were identified for sediment (note that some constituents were evaluated for both water and sediment). These constituents included various types of organic compounds, trace elements and other inorganic constituents, and radionuclides. Some of these constituents are difficult to analyze, whereas others are mixtures, isomers, congeners, salts, and acids of other constituents; therefore, modifications to the list of high-priority constituents for ambient monitoring could be made on the basis of the availability of suitable methods for preparation, extraction, or analysis. An additional 1,460 constituents were placed into Tiers 2 or 3 for water or sediment, including some constituents that had been placed into Tier 1 for a different matrix; 436 constituents were placed into Tier 2 for water and 246 constituents into Tier 2 for sediment; 979 constituents were placed into Tier 3 for water and 779 constituents into Tier 3 for sediment.

Scientific Investigations Report↗

USGS2009

Bankfull discharge and channel characteristics of streams in New York State

Equations that relate drainage area to bankfull discharge and channel characteristics (such as width, depth, and cross-sectional area) at gaged sites are needed to help define bankfull discharge and channel characteristics at ungaged sites and can be used in stream-restoration and protection projects, stream-channel classification, and channel assessments. These equations are intended to serve as a guide for streams in areas of similar hydrologic, climatic, and physiographic conditions. New York State contains eight hydrologic regions that were previously delineated on the basis of high-flow (flood) characteristics. This report seeks to increase understanding of the factors affecting bankfull discharge and channel characteristics to drainage-area size relations in New York State by providing an in-depth analysis of seven previously published regional bankfull-discharge and channel-characteristics curves. Stream-survey data and discharge records from 281 cross sections at 82 streamflow-gaging stations were used in regression analyses to relate drainage area to bankfull discharge and bankfull-channel width, depth, and cross-sectional area. The R 2 and standard errors of estimate of each regional equation were compared to the R 2 and standard errors of estimate for the statewide (pooled) model to determine if regionalizing data reduced model variability. It was found that regional models typically yield less variable results than those obtained using pooled statewide equations, which indicates statistically significant regional differences in bankfull-discharge and channel-characteristics relations. Statistical analysis of bankfull-discharge relations found that curves for regions 4 and 7 fell outside the 95-percent confidence interval bands of the statewide model and had intercepts that were significantly diferent (p≤0.10) from the other five hydrologic regions.Analysis of channel-characteristics relations found that the bankfull width, depth, and cross-sectional area curves for region 3 were significantly different p(≤0.05) from the other six regions. It was hypothesized that some regional variability could be reduced by creating models for streams with similar physiographic and climatic characteristics. Available data on streamflow patterns and previous regional-curve research suggested that mean annual runoff, Rosgen stream type, and water-surface slope were the variables most likely to influence regional bankfull discharge and channel characteristics to drainage-area size relations. Results showed that although all of these factors had an influence on regional relations, most stratified models have lower 2 values and higher standard errors of estimate than the regional models. The New York statewide (pooled) bankfull-discharge equation and equations for regions 4 and 7 were compared with equations for four other regions in the Northeast to evaluate region-to-region differences, and assess the ability of individual curves to produce results more accurate than those that would be obtained from one model of the northeastern United States. Results indicated that model slopes lack significant diferences, though intercepts are significantly different. Comparison of bankfull-discharge estimates using different models shows that results could vary by as much as 100 percent depending on which model was used and indicated that regionalization improved model accuracy.

New York↗

USGS2018

Geologic, hydrologic, and water-quality data from multiple-well monitoring sites in the Bunker Hill and Yucaipa Groundwater Subbasins, San Bernardino County, California, 1974–2016

In 1974, the U.S. Geological Survey (USGS), in cooperation with the San Bernardino Valley Municipal Water District, initiated a study to assess the regional groundwater resources in the Bunker Hill Subbasin of the Upper Santa Ana Valley Groundwater Basin in San Bernardino County, California. The study area expanded east into the Yucaipa Subbasin in 1996. This report compiles the geologic (borehole lithology and geophysical logs) and hydrologic (water-quality and water-level) data collected from 1974–2016 for 11 multiple-well monitoring sites (48 individual wells) constructed by the USGS in the Bunker Hill (7 sites) and Yucaipa (4 sites) Groundwater Subbasins. Approximately 240 water-quality samples from the 11 sites were analyzed for constituents including major and minor ions, nutrients, selected trace elements, organic wastewater compounds (OWCs), volatile organic compounds (VOCs), pesticides and pesticide degradates, the stable isotopes of hydrogen, oxygen, and nitrogen, and the radiogenic isotopes of tritium and carbon-14. All environmental data associated with these sites are available on the project web page for the San Bernardino Optimal Basin Management study ( https://ca.water.usgs.gov/sanbern/ ) and the Yucaipa Valley Hydrogeology study ( https://ca.water.usgs.gov/yucaipa/ ). Quality-assurance blank samples were processed periodically throughout the study and show that approximately 2.4 percent of the analytical results for major and minor ions, trace elements, and nutrients, and 1.5 percent of the results for VOCs fall below the acceptable study reporting limits and therefore are censored.

California↗

USGS2010

Magnetotelluric survey to characterize the Sunnyside porphyry copper system in the Patagonia Mountains, Arizona

The Sunnyside porphyry copper system is part of the concealed San Rafael Valley porphyry system located in the Patagonia Mountains of Arizona. The U.S. Geological Survey is conducting a series of multidisciplinary studies as part of the Assessment Techniques for Concealed Mineral Resources project. To help characterize the size and resistivity of the mineralized area beneath overburden, a regional east-west magnetotelluric sounding profile was acquired. This is a data release report of the magnetotelluric sounding data collected along the east-west profile; no interpretation of the data is included.

Open-File Report↗

USGS1981

Eastern Gulf of Alaska seismicity: Annual report to the National Oceanic and Atmospheric Administration for April 1, 1980, through March 31, 1981

The objective of this research is to collect and analyze data on earthquake activity in the northeast Gulf of Alaska (NEGOA) and adjacent onshore areas in order to develop a better regional seismotectonic model and more accurately assess the earthquake potential. This information is critical to the establishment of criteria for the safe development of oil and gas. Large (M s > 7) historical earthquakes have occurred in and around the NEGOA, and recent studies suggest that the NEGOA is a likely site for a magnitude 8 or larger earthquake to occur within the next two or three decades. A great earthquake (Ms>8) associated with low-angle oblique underthrusting of the sea floor beneath continental shelf could be accompanied by strong ground shaking throughout much of the eastern Gulf of Alaska, possibly from Cross Sound to Kayak Island (Page, 1975), and could trigger tsunamis, seiches, and submarine slumping, any of which could be hazardous to offshore and coastal structures (Meyers, 1976).

Alaska↗

USGS2020

An enhanced hydrologic stream network based on the NHDPlus medium resolution dataset

The National Hydrography Dataset Plus, Version 2.1 (NHDPlusV2.1) is an attribute-rich digital stream network for the conterminous United States, serving as a foundational infrastructure for reporting hydrologic information at both regional and national scales. SPAtially Referenced Regressions On Watershed attributes (SPARROW) is a process-based statistical model that relies on a digital hydrologic network like NHDPlusV2.1 to establish spatial relations between quantities of monitored contaminant loads and contaminant sources, accounting for the physical characteristics along flow paths affecting contaminant transport. The U.S. Geological Survey National Water Quality Assessment project adopted and modified the medium-resolution NHDPlusV2.1 network for use as the primary framework supporting SPARROW modeling. This report describes the enhancements made to improve the routing capabilities and the value-added attributes of NHDPlusV2.1 to support modeling and other hydrologic analyses. These enhancements include corrections to inconsistencies in network/routing information, filling in missing attribute values of associated characteristics, accounting of water use affecting flow, new variables useful for interpreting network data, revised flowline attributes such as slope and flow, and incorporation of ancillary spatial data into the network. The resulting dataset containing the enhancements to the network is named E2NHDPlusV2_US. Although the enhancements described in the report were developed for use in SPARROW modeling, the enhancements are expected to be useful for a wide variety of hydrologic studies within the United States.

Conterminous United States↗