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At least 667 records · Page 37Linked to original sources
USGS2010

Macroinvertebrate-based assessment of biological condition at selected sites in the Eagle River watershed, Colorado, 2000-07

The U.S. Geological Survey (USGS), in cooperation with the Colorado River Water Conservation District, Eagle County, Eagle River Water and Sanitation District, Upper Eagle Regional Water Authority, Colorado Department of Transportation, City of Aurora, Town of Eagle, Town of Gypsum, Town of Minturn, Town of Vail, Vail Resorts, Colorado Springs Utilities, Denver Water, and the U.S. Department of Agriculture Forest Service (FS), compiled macroinvertebrate (73 sites, 124 samples) data previously collected in the Eagle River watershed from selected USGS and FS studies, 2000-07. These data were analyzed to assess the biological condition (that is, biologically ?degraded? or ?good?) at selected sites in the Eagle River watershed and determine if site class (for example, urban or undeveloped) described biological condition. An independently developed predictive model was applied to calculate a site-specific measure of taxonomic completeness for macroinvertebrate communities, where taxonomic completeness was expressed as the ratio of observed (O) taxa to those expected (E) to occur at each site. Macroinvertebrate communities were considered degraded at sites were O/E values were less than 0.80, indicating that at least 20 percent of expected taxa were not observed. Sites were classified into one of four classes (undeveloped, adjacent road or highway or both, mixed, urban) using a combination of riparian land-cover characteristics, examination of topographic maps and aerial imagery, screening for exceedances in water-quality standards, and best professional judgment. Analysis of variance was used to determine if site class accounted for variability in mean macroinvertebrate O/E values. Finally, macroinvertebrate taxa observed more or less frequently than expected at urban sites were indentified. This study represents the first standardized assessment of biological condition of selected sites distributed across the Eagle River watershed. Of the 73 sites evaluated, just over half (55 percent) were considered in good biological condition (O/E greater than 0.80). The remaining sites were either consistently biologically degraded (30 percent; O/E less than 0.80) or varied annually between good and degraded condition (15 percent; O/E is less than or greater than 0.80). Sites primarily affected by urbanization were among the most severely degraded (lowest O/E values) when compared to other site classes. Although most urban sites were among the most severely degraded (lowest O/E values), a few sites had nearly intact macroinvertebrate communities (O/E near 1.0). Similar observations were noted among sites classified as mixed. Thirteen macroinvertebrate taxa were indentified that occurred more or less frequently than expected at urban sites. Additionally, six other taxa were impartial (tolerant) to the same conditions. Combined, these 19 taxa provide an opportunity to enhance the interpretation of future studies in the Eagle River watershed, but will require better insight into the responses of these taxa to specific stressors. Understanding the sources of variability affecting biological condition along with why some sites expected to be degraded, but showed otherwise, will have clear implications for mitigation efforts. Integrating results of this study with field and laboratory investigations will greatly enhance the ability to identify causal factors affecting biological condition at degraded sites, the logical next step. Information generated from such integrative studies will be imperative for well targeted mitigation efforts in the Eagle River watershed.

Scientific Investigations Report↗
USGS2017

Macroinvertebrate communities evaluated prior to and following a channel restoration project in Silver Creek, Blaine County, Idaho, 2001-16

The U.S. Geological Survey, in cooperation with Blaine County and The Nature Conservancy, evaluated the status of macroinvertebrate communities prior to and following a channel restoration project in Silver Creek, Blaine County, Idaho. The objective of the evaluation was to determine whether 2014 remediation efforts to restore natural channel conditions in an impounded area of Silver Creek caused declines in local macroinvertebrate communities. Starting in 2001 and ending in 2016, macroinvertebrates were sampled every 3 years at two long-term trend sites and sampled seasonally (spring, summer, and autumn) in 2013, 2015, and 2016 at seven synoptic sites. Trend-site communities were collected from natural stream-bottom substrates to represent locally established macroinvertebrate assemblages. Synoptic site communities were sampled using artificial (multi-plate) substrates to represent recently colonized (4–6 weeks) assemblages. Statistical summaries of spatial and temporal patterns in macroinvertebrate taxonomic composition at both trend and synoptic sites were completed. The potential effect of the restoration project on resident macroinvertebrate populations was determined by comparing the following community assemblage metrics: Total taxonomic richness (taxa richness); Total macroinvertebrate abundance (total abundance); Ephemeroptera, Plecoptera, Trichoptera (EPT) richness; EPT abundance; Simpson’s diversity; and Simpson’s evenness for periods prior to and following restoration. A significant decrease in one or more metric values in the period following stream channel restoration was the basis for determining impairment to the macroinvertebrate communities in Silver Creek. Comparison of pre-restoration (2001–13) and post‑restoration (2016) macroinvertebrate community composition at trend sites determined that no significant decreases occurred in any metric parameter for communities sampled in 2016. Taxa and EPT richness of colonized assemblages at synoptic sites increased significantly from pre-restoration in 2013 to post-restoration in 2015 and 2016. Similarly, total and EPT abundances at synoptic sites showed non-significant increases from 2013 to 2015 and 2016. Significant seasonal differences in macroinvertebrate assemblages were apparent at synoptic site locations and likely reflected typical life-history patterns of increased insect emergence and development in the late spring and early summer months. Taxa and EPT richness were each significantly higher in spring and summer than in autumn, and total abundances were significantly higher in spring than in summer and autumn. No significant differences in community diversity or evenness of colonized communities were noted at synoptic site locations between pre- and post-restoration years or among seasons. Select community-metric results from the trend- and synoptic ‑ site sampling indicated that the Silver Creek restoration effort in 2014 did not result in a significant decline in resident macroinvertebrate communities.

Idaho↗
USGS2024

Introduction to recommended capabilities and instrumentation for volcano monitoring in the United States

Introduction The National Volcano Early Warning System (NVEWS) was authorized and partially funded by the U.S. Government in 2019. In response, the U.S. Geological Survey (USGS) Volcano Hazards Program asked its scientists to reflect on and summarize their views of best practices for volcano monitoring. The goal was to review and update the recommendations of a previous report (Moran and others, 2008) and to provide a more detailed analysis of capabilities and instrumentation for monitoring networks for U.S. volcanoes. This Scientific Investigations Report and its chapters reflect those USGS scientists’ views and summaries and will serve as a guide for future network upgrades funded through NVEWS. Given the well-documented hazards posed by volcanoes to population centers and aviation (for example, Blong, 1984; Scott, 1989; Neal and others, 1997, 2019; Guffanti and others, 2010; Shroder and Papale, 2014; Prata and Rose, 2015; Palmer, 2020), volcano monitoring is critical for ensuring public safety and for mitigating the impacts of volcanic activity. Accurate and timely forecasts are facilitated by well-designed monitoring networks that are in place long enough to allow for background behavior to be recognized and understood. Because precursory signals may be limited and unrest may progress rapidly to an eruption, our goal is to deploy monitoring systems that enable detection of the reactivation of dormant volcanoes as early as possible, allowing for public safety and risk mitigation. NVEWS planning is also informed by the results of Ewert and others (2005, 2018), whereby 161 U.S. volcanoes are currently categorized and ranked commensurate with their relative threat. In each chapter, author(s) considered the need for some redundancy of instrumentation and telemetry, given the likelihood of occasional equipment failure, particularly in extreme and remote environments. Establishing digital telemetry networks requires advanced planning, sighting, radio-shot testing, and, inevitably, troubleshooting in the field. This is harder to achieve rapidly during a crisis; thus, an important goal for monitoring U.S. volcanoes is to establish digital telemetry backbones with redundancy and extra capacity to absorb additional instruments should a volcano begin to exhibit signs of unrest (fig. A1). The National Telecommunications and Information Administration (NTIA) imposed new regulations in the United States, eliminating the use of older analog radios for many purposes, which had been one previous means for redundant data delivery. However, the resulting conversion from analog to digital systems usefully enables stations to accommodate new and multivariate real-time data streams (for example, Global Navigation Satellite System [GNSS] receivers, infrasound arrays, gas spectrometers, visible and infrared cameras, and broadband seismometers). We note that other USGS and broader national and international hazard programs can leverage NVEWS instrumentation plans. Examples of this include the following: Improved seismic coverage of volcanoes will increase the capability of the USGS Earthquake Hazards Program to detect and locate earthquakes, estimate ground shaking, and provide timely early warnings through the ShakeAlert Earthquake Early Warning System (Given and others, 2018). The National Oceanic and Atmospheric Administration’s Tsunami Program will benefit from additional seismic stations, particularly within the sparsely instrumented Aleutian Islands, Northern Mariana Islands, and American Samoa. Infrasound stations can detect signals from landslides, debris flows and lahars, floods, and weather events, providing benefits to the National Weather Service and the USGS Landslide Hazards Program.

Scientific Investigations Report↗
USGS2015

National Earthquake Information Center systems overview and integration

Overview The primary mission of the U.S. Geological Survey (USGS) National Earthquake Information Center (NEIC) is comprehensive global earthquake monitoring (M4.5 or larger) and complete seismic monitoring of the United States for all significant earthquakes (M3.0 or larger or felt). In recent years, the NEIC has assumed a more prominent role in local and regional seismic monitoring, backup capabilities, and special studies. The NEIC uses numerous scientific algorithms to produce information products for local, national, and international disaster responders; infrastructure corporations (for example, utility providers and insurers); U.S. embassies worldwide; news agencies; national and international earth science research communities; and millions of public users. To support this mission, the NEIC operates a constant service to derive numerous information products as rapidly and accurately as possible. Derived information products and data sets provide a wealth of related earthquake information and include products such as location, magnitude, maps of shaking intensity, moment tensors, phase arrivals, and loss and damage reports. These information products are automatically derived in near real-time and refined over time. Earthquake information products vary from well formatted text files, to binary files, to directories full of many files. A team of analysts, who provide constant coverage, 24 hours a day, seven days a week, 365 days a year, review the acquired data and automatically derived products (1) in near real-time for rapid release and (2) in the weeks following events to produce historical catalogs of global earthquakes in support of scientific research. Data and products are reviewed both in near real-time for rapid release and in the weeks following events to produce historical catalogs of global earthquakes in support of scientific research. At the present time, the NEIC publishes data for approximately 25,000 earthquakes annually. The NEIC software system that supports this service and mission comprises many subsystems. The internals of each subsystem are often complex, but the integration between all of the subsystems is well defined, standardized, and straightforward. This Open-File Report describes the systems’ integration infrastructure and how all the subsystems fit together. It provides summary views of the system as a whole, along with detailed views of the inputs, outputs, and dependencies for each subsystem. It also outlines the many shared data services that support these subsystems and applications as well as external customers. The NEIC systems-integration effort is ongoing. Additional integration steps, needed to reach our goals, are discussed. It is important to note that this document provides a brief introduction to the work of dozens of software developers and IT specialists, spanning in many cases more than a decade. References to significant amounts of supporting documentation, code, and information are supplied within.

Open-File Report↗
USGS2017

Scientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan

Introduction The purpose of this document is to describe a strategy by which monitoring and research data in the natural and social sciences will be collected, analyzed, and provided to the U.S. Department of the Interior (DOI), its bureaus, and to the Glen Canyon Dam Adaptive Management Program (GCDAMP) in support of implementation of the Glen Canyon Dam Long-Term Experimental and Management Plan (LTEMP) (U.S. Department of the Interior, 2016a). The selected alternative identified in the LTEMP Record of Decision (ROD) (U.S. Department of the Interior, 2016b) describes various data collection, analysis, modeling, and interpretation efforts to be conducted by the U.S. Geological Survey’s (USGS) Grand Canyon Monitoring and Research Center (GCMRC), partner agencies, and cooperators that will inform decisions about operations of Glen Canyon Dam and management of downstream resources between 2017 and 2037, the performance period of the LTEMP. General data collection, analysis, modeling, and interpretation activities are described in this science plan, whereas specific monitoring and research activities and detailed study plans are to be described in the GCDAMP’s triennial work plans (TWPs) to be developed by the Bureau of Reclamation and GCMRC with input from partner agencies and cooperators during the LTEMP period, which are to be reviewed and recommended by the GCDAMP and approved by the Secretary of the Interior. The GCDAMP consists of several components, the primary committee being the Adaptive Management Work Group (AMWG). This Federal advisory committee is composed of 25 agencies and stakeholder groups and is chaired by the Secretary of the Interior’s designee. The AMWG makes recommendations to the Secretary of the Interior concerning operations of Glen Canyon Dam and other experimental management actions that are intended to fulfill some obligations of the Grand Canyon Protection Act of 1992. The Technical Work Group (TWG) is a subcommittee of the AMWG and provides technical advice to the AMWG. It is composed of technical and science representatives from the same agencies and stakeholder groups who serve on the AMWG. GCMRC is the primary science provider to the GCDAMP and also coordinates many aspects of the science performed by cooperators and partner agencies. The Science Advisors Program provides independent science reviews and advice at the request of the GCDAMP. The plan proposed here necessarily depends on (1) the protocol for decision-making and the requirements for scientific data reporting described in the LTEMP ROD, (2) the priorities of the GCDAMP as directed by the LTEMP ROD (see Department of the Interior, 2016b, section 6.1), (3) the priorities for monitoring and research in the conservation measures section of the Biological Opinion for the LTEMP (U.S. Department of the Interior, 2016b, LTEMP ROD attachment E), (4) the priorities for resource management and information needs established by Federal and State resource-management agencies within the GCDAMP, (5) scientific understanding about the linkage between the status of those resources and operations of Glen Canyon Dam, and (6) the need to resolve existing scientific uncertainties about the linkage between dam operations and the condition of resources. We note that resource-management prioritization is fundamentally a policy decision charged specifically to DOI for the Colorado River in Glen and Grand Canyons, as outlined most recently in the LTEMP ROD, and is not the responsibility of the GCMRC. However, it is the responsibility of the GCMRC to describe the nature of scientific understanding, the nature of scientific uncertainty, and the risk of making resourcemanagement decisions in the face of existing scientific uncertainty. The goals of science activities in the next 20 years are to inform operational decisions regarding Glen Canyon Dam operations described in the LTEMP ROD, resolve remaining scientific uncertainties, and to monitor resource trends that are affected entirely, or in part, by dam operations.

Open-File Report↗
USGS2005

Trends in streamflow, sedimentation, and sediment chemistry for the Wolf River, Menominee Indian Reservation, Wisconsin, 1850-1999

Historical trends in streamflow, sedimentation, and sediment chemistry of the Wolf River were examined for a 6-mile reach that flows through the southern part of the Menominee Indian Reservation and the northern part of Shawano County, Wis. Trends were examined in the context of effects from dams, climate, and land-cover change. Annual flood peaks and mean monthly flow for the Wolf River were examined for 1907-96 and compared to mean annual and mean monthly precipitation. Analysis of trends in sedimentation (from before about 1850 through 1999) involved collection of cores and elevation data along nine valley transects spanning the Wolf River channel, flood plain, and backwater and impounded areas; radioisotope analyses of impounded sediment cores; and analysis of General Land Office Survey Notes (1853-91). Trends in sediment chemistry were examined by analyzing samples from an impoundment core for minor and trace elements. Annual flood peaks for the Wolf River decreased during 1907-49 but increased during 1950-96, most likely reflecting general changes in upper-atmospheric circulation patterns from more zonal before 1950 to more meridional after 1950. The decrease in flood peaks during 1907-49 may also, in part, be due to forest regrowth. Mean monthly streamflow during 1912-96 increased for the months of February and March but decreased for June and July, suggesting that spring snowmelt occurs earlier in the season than it did in the past. Decreases in early summer flows may be a reflection earlier spring snowmelt and large rainstorms in early spring rather than early summer. These trends also may reflect upper-atmospheric circulation patterns. The Balsam Row Dam impoundment contains up to 10 feet of organic-rich silty clay and has lost much of its storage capacity. Fine sediment has accumulated for 1.8 miles upstream from the Balsam Row Dam. Historical average linear and mass sedimentation rates in the Balsam Row impoundment were 0.09 feet per year and 1.15 pounds per square foot per year for 1927-62 and 0.10 feet per year and 1.04 pounds per square foot per year for 1963-99. Sedimentation in the impoundment was episodic and was associated with large floods, especially the flood-related failure of the Keshena Falls Dam in 1972 and a large flood in 1973. Sand deposition is common in the Wolf River upstream from the impounded reach for 2.5 miles and is caused by the base-level increase associated with the Balsam Row Dam. Some sand deposition also may have been associated with logging and log drives in the late 1800s and the failure of the Keshena Falls Dam. In the upstream 1.5-mile part of the studied reach, the substrate is mainly rocky; however, about 2,000 feet downstream from Keshena Falls, the channel has narrowed and incised since the 1890s, likely related to human alterations associated with logging, log drives, and (or) changes in hydraulics and sediment characteristics associated with completion of the Keshena Falls Dam and head race in 1908. Minor- and trace-element concentrations in sediment from Balsam Row impoundment and other depositional areas along the Wolf River generally reflect background conditions as affected by watershed geology and historical inputs from regional and local atmospheric deposition.

Wisconsin↗
USGS2023

Groundwater-flow model of the Treasure Valley, southwestern Idaho, 1986–2015

Most of the population of the Treasure Valley and the surrounding area of southwestern Idaho and easternmost Oregon depends on groundwater for domestic supply, either from domestic or municipal-supply wells. Current and projected rapid population growth in the area has caused concern about the long-term sustainability of the groundwater resource. In 2016, the U.S. Geological Survey, in cooperation with the Idaho Water Resource Board and the Idaho Department of Water Resources, began a project to construct a numerical groundwater-flow model of the westernmost portion of the western Snake River Plain aquifer system, called the Treasure Valley. The development of the model was guided by several objectives, including: to improve the understanding of groundwater and surface water interactions; to facilitate conjunctive water management; to provide a tool for water resources planning; and to provide a tool for water allocation. The model was constructed with a spatial scale and level of detail that aimed to meet these objectives while balancing the sometimes-competing goals of fast runtimes, numerical stability, usability, and parsimony. The Treasure Valley Groundwater Flow Model (TVGWFM) is a three-dimensional finite-difference numerical model constructed using MODFLOW 6 (Langevin and others, 2017, Documentation for the MODFLOW 6 Groundwater Flow Model: U.S. Geological Survey Techniques and Methods, book 6, chap. A55, 197 p., https://doi.org/10.3133/tm6A55 ). The model covers the westernmost portion of the western Snake River Plain and is discretized into a regular grid of 64 by 65 cells with a side length of 1 mile and 6 layers of varying depth and active area. A historical model period was developed consisting of 360 month-long stress periods for 1986–2015. The model builds upon previous modeling efforts by adding a transient period, incorporating new head and discharge observations to constrain parameters, incorporating information from the hydrogeologic framework model (HFM) of Bartolino (2019, Hydrogeologic framework of the Treasure Valley and surrounding area, Idaho and Oregon: U.S. Geological Survey Scientific Investigations Report 2019–5138, https://doi.org/10.3133/sir20195138 ) and incorporating refined estimates of evapotranspiration and irrigation classification of lands in the study area. The TVGWFM includes all significant components of recharge to and discharge from the aquifer. Inflows include canal seepage, irrigation and precipitation recharge, mountain-front recharge, rivers and stream seepage, and seepage from Lake Lowell. Outflows include discharge to agricultural drainage ditches, discharge to rivers and streams, pumping, and discharge to Lake Lowell. Each recharge or discharge component is represented separately using individual MODFLOW 6 packages. Parameter values were derived with a combination of trial-and-error steps and automated parameter estimation using PEST software (Doherty, J.E., 2005, PEST, model-independent parameter estimation–User manual: Watermark Numerical Computing, https://pesthomepage.org/documentation ). Parameter estimates were constrained with several types of observation data, including water levels, water level changes, vertical water level differences, drain discharges, change in drain discharges, river seepage, seepage from Lake Lowell, and change in seepage from Lake Lowell. Material properties from the hydrogeologic framework were also used to assign the minimum and maximum values of some parameters. A final parameter realization was reached that minimized residuals between the observed and modelled values for the various observation groups. Mean residuals for the observation groups were 15.4 feet (ft) for water levels, 0.2 ft for water level changes, 19.4 ft for vertical water level differences, −3.9 cubic feet per second (ft 3 /s) for drain discharges, 0.0 ft 3 /s for changes in drain discharge, 45.0 ft 3 /s for river seepage, −40.1 ft 3 /s for Lake Lowell seepage, and 126.3 ft 3 /s for changes in Lake Lowell seepage. The quality of the model’s fit to observations varied spatially, with notable areas of under- or over-simulation of water levels present to the northwest and southwest of Lake Lowell, in the foothills along the eastern model boundary, and near the City of Eagle. Trends were observed in the residuals of many of the observation groups, indicating that the model is missing or not fully reproducing some phenomena that are observed in the system. The TVGWFM can be used as a tool for water resource planning, for understanding the interactions of groundwater and surface water at a basin scale, and for facilitating conjunctive management, but may lack the precision needed for water rights administration at a local scale. Additional sources of uncertainty or limitations of the model are noted. The quantity and spatial distribution of canal seepage and infiltration of irrigation water recharge, the largest sources of recharge to the system, are unknown and approximated indirectly. There is poor understanding of how canal seepage and incidental recharge change as land is converted from agricultural (irrigated) to suburban (semi-irrigated). These uncertainties will affect any scenarios that investigate changes to land use or irrigation practices. Finally, the model has relatively high water-level residuals around and to the southwest of Lake Lowell and should not be used to estimate water level effects in that region. The model was built with multiple, broadly expressed objectives and did not optimize performance for specific uses. However, the model and the tools included in an associated data release provide ample flexibility to improve the model for future uses. Adjustments and improvements could be made by refining the model in an area of interest, collecting additional calibration data, applying more rigorous boundary conditions, or re-estimating model parameters to optimize model performance for a specific model forecast.

Idaho↗
USGS1998

Quality-Assurance/Quality-Control Manual for Collection and Analysis of Water-Quality Data in the Ohio District, US Geological Survey

The U.S. Geological Survey (USGS), Water Resources Division (WRD), requires that quality-assurance/quality-control (QA/QC) activities be included in any sampling and analysis program. Operational QA/QC procedures address local needs while incorporating national policies. Therefore, specific technical policies were established for all activities associated with water-quality project being done by the Ohio District. The policies described in this report provide Ohio District personnel, cooperating agencies, and others with a reference manual on QA/QC procedures that are followed in collecitng and analyzing water-quality samples and reporting water-quality information in the Ohio District. The project chief, project support staff, District Water-Quality Specialist, and District Laboratory Coordinator are all involved in planning and implementing QA/QC activities at the district level. The District Chief and other district-level managers provide oversight, and the Regional Water-Quality Specialist, Office of Water Quality (USGS headquarters), and the Branch of Quality Systems within the Office of Water Quality create national QA/QC polices and provide assistance to District personnel. In the literature, the quality of all measurement data is expressed in terms of precision, variability, bias, accuracy, completeness, representativeness, and comparability. In the Ohio District, bias and variability will be used to describe quality-control data generated from samples in the field and laboratory. Each project chief must plan for implementation and financing of QA/QC activities necessary to achieve data-quality objectives. At least 15 percent of the total project effort must be directed toward QA/QC activities. Of this total, 5-10 percent will be used for collection and analysis of quality-control samples. This is an absolute minimum, and more may be required based on project objectives. Proper techniques must be followed in the collection and processing of surface-water, ground-water, biological, precipitation, bed-sediment, bedload, suspended-sediment, and solid-phase samples. These techniques are briefly described in this report and are extensively documented. The reference documents listed in this report will be kept by the District librarian and District Water-Quality Specialist and updated regularly so that they are available to all District staff. Proper handling and documentation before, during, and after field activities are essential to ensure the integrity of the sample and to correct erroneous reporting of data results. Field sites are to be properly identified and entered into the data base before field data-collection activities begin. During field activities, field notes are to be completed and sample bottles appropriately labeled a nd stored. After field activities, all paperwork is to be completed promptly and samples transferred to the laboratory within allowable holding times. All equipment used by District personnel for the collection and processing of water-quality samples is to be properly operated, maintained, and calibrated by project personnel. This includes equipment for onsite measurement of water-quality characteristics (temperature, specific conductance, pH, dissolved oxygen, alkalinity, acidity, and turbidity) and equipment and instruments used for biological sampling. The District Water-Quality Specialist and District Laboratory Coordinator are responsible for preventive maintenance and calibration of equipment in the Ohio District laboratory. The USGS National Water Quality Laboratory in Arvada, Colo., is the primary source of analytical services for most project work done by the Ohio District. Analyses done at the Ohio District laboratory are usually those that must be completed within a few hours of sample collection. Contract laboratories or other USGS laboratories are sometimes used instead of the NWQL or the Ohio District laboratory. When a contract laboratory is used, the projec

Water-Resources Investigations Report↗
USGS1975

Fluid inclusion studies of vein, pipe, and replacement deposits, northwestern San Juan Mountains, Colorado

Base and precious metal ores valued in excess of $300 million have been mined from vein, pipe, and replacement deposits located on the northwest side of, and structurally related to, the middle Tertiary Silverton caldera. A belt of normal faults radial to the caldera contains veins which have been mined for as much as 15,000 feet (4,600 m) along strike and 3,700 feet (1,100 m) downdip. Structural relations, metal distributions, and fluid inclusion data suggest that many of the veins were open at the same general time and received the same mineralization. Fluid inclusions in quartz and sphalerite of the main ore stage of the Argentine and adjoining veins have filling temperatures ranging from 315 degrees to 249 degrees C and salinities from 7.9 to 0.1 wt percent NaCl equivalent. However, the majority of inclusions from base metal and gold stages are in a relatively narrow range near 280 degrees to 290 degrees C and salinities are unusually low (less than 2 wt %). Filling temperatures in postsulfide quartz and fluorite are as low as 153 degrees C and salinities are generally less than 0.5 wt percent. A pressure correction of about +25 degrees C should be added to the filling temperatures. Ore fluids were physically homogeneous liquids over the 3,700-foot (1,100 m) vertical and 11,200-foot (3,400 m) lateral range studied and no systematic variations in filling temperatures or salinity in this space are noted, but significant fluctuations are evident locally. Recently developed base metal replacement deposits occur in the Eocene Telluride Conglomerate adjacent to many metal-bearing veins. Calc-silicate alteration of the conglomerate host was probably by moderately saline fluids that ranged in temperature from 320 degrees to about 400 degrees C. Quartz-bearing clasts in altered zones contain secondary halitebearing inclusions with filling temperatures of about 250 degrees C and salinities about 34 wt percent; such inclusions are not known from the base metal stage and are interpreted to have been preore. Hydrothermal quartz, sphalerite, and calcite from replacement pods contain inclusions with filling temperatures ranging from 204 degrees to 309 degrees C and salinities from 11.2 to 0.2 wt percent. That the replacement zones and throughgoing veins are genetically related is suggested by the similarity of filling temperatures and compositions of base metal-stage fluid inclusions and by structural evidence. Small high-grade pipe deposits of base and precious metals occur along the ring-fault zone of the Silverton caldera. Filling temperatures for inclusions in quartz, sphalerite, and barite of the main ore stage of these deposits range from 216 degrees to 308 degrees C and salinities range from 1.6 to 0.2 wt percent NaCl. Quartz in altered wall rocks and silicified capping contains moderately saline secondary inclusions with relatively uniform liquid: vapor ratios that suggest filling temperatures of about 225 degrees to 300 degrees C. From the available samples there is no fluid inclusion evidence for boiling. Throttling, which had been hypothesized to explain the telescoped nature of the pipe ores, is neither substantiated nor discredited by the inclusion data.

Colorado↗
USGS2022

The role of organic matter diversity on the Re-Os systematics of organic-rich sedimentary units: Insights into the controls of isochron age determinations from the lacustrine Green River Formation

The range of 187 Re/ 188 Os values measured from samples of five organic-rich lacustrine mudstones units in the Eocene Green River Formation in the easternmost Uinta Basin covaries with organic matter diversity driven by changing water column conditions. A set of samples from the Douglas Creek Member has the highest pristane/phytane ratio and lowest β-carotane/ n -C 30 ratio compared to overlying units, indicating deposition in an oxic-anoxic environment with low salinity that would have allowed for the accumulation of a diverse assemblage of aquatic organisms. These samples define the broadest 187 Re/ 188 Os range of 1504. In contrast, samples from the R6 and Mahogany zones possess lower pristane/phytane ratios and higher β-carotane/ n -C 30 ratios indicating deposition in a more restricted lacustrine environment with elevated salinities and alkalinities that would have limited aquatic organic matter diversity. The R6 and Mahogany zones have the narrowest range of 187 Re/ 188 Os values measured in this study of 254.9 and 154.6, respectively. As noted by previous workers, these results suggest that organic matter diversity plays a primary role in determining the range of 187 Re/ 188 Os ratios in a sample set, and in turn the uncertainty of Re-Os age determinations from organic-rich sedimentary rocks. The Re-Os data from the R3 zone and R6 zone yield ages of 49.7 ± 3.4 Ma and 42.0 ± 18 Ma, respectively, which are statistically indistinguishable based on 2σ uncertainty from three previously reported Re-Os age determinations and those provided by 40 Ar/ 39 Ar geochronology of interbedded volcanic ash beds. Although the age uncertainty is high, these findings further highlight the importance of Re-Os geochronology in lacustrine basins, particularly those with thick mudstone successions that lack volcanic ash layers, reliable biostratigraphy , or magnetostratigraphic control. In these cases, even ages with large uncertainties can be useful to constrain burial history and thermal history models. Together, the initial 187 Os/ 188 Os ratios of five sets of samples analyzed from the Uinta Basin define the largest Os isotope stratigraphic record from any lacustrine basin compiled to date and record a shift from a value of 1.40 to 1.48 between the R3 and R4 zones in the lower part of the Parachute Creek Member. This small shift may signify a change in the chemical weathering products that entered the lake preserved 20 to 50 m above the contact between the Douglas Creek and the lower Parachute Creek members during a period when the basin transitioned from a shallow lake with mostly open hydrology to an alkaline lake with more frequent basin restrictions.

Colorado, Utah, Wyoming↗
USGS2010

Streamflow, Water Quality, and Constituent Loads and Yields, Scituate Reservoir Drainage Area, Rhode Island, Water Year 2006

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2006 (October 1, 2005, to September 30, 2006). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2006 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2006. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 42 cubic feet per second (ft3/s) to the reservoir during WY 2006. For the same time period, annual mean streamflows1 measured (or estimated) for the other monitoring stations in this study ranged from about 0.60 to 26 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,600,000 kilograms (kg) of sodium and 2,500,000 kg of chloride to the Scituate Reservoir during WY 2006; sodium and chloride yields for the tributaries ranged from 15,000 to 100,000 kilograms per square mile (kg/mi2) and from 22,000 to 180,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 24.6 milligrams per liter (mg/L), median nitrite concentration was 0.001 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.07 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 43 and 23 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 230 kg/d (81 kg/d/mi2), 17 g/d (4.4 g/d/mi2), 130 g/d (50 g/d/mi2), 470 g/d (210 g/d/mi2), and 2,100 million colony forming units per day (CFU?106/d) (1,300 CFU?106/d/mi2) and 670 CFU?106/d (420 CFU?106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Open-File Report↗
USGS2021

Borehole analysis, single-well aquifer testing, and water quality for the Burnpit well, Mount Rushmore National Memorial, South Dakota

Mount Rushmore National Memorial (hereafter referred to as “the memorial”), in western South Dakota, is maintained by the National Park Service (NPS) and includes 1,278 acres of land in the east-central part of the Black Hills. An ongoing challenge for NPS managers at the memorial is providing water from sustainable and reliable sources for operations, staff, and the increasing number of visitors. In 2020, the U.S. Geological Survey (USGS) and NPS completed a hydrological study of the Burnpit well (well 5), a 580-foot-deep open hole groundwater well completed in metamorphic (crystalline) rock at the memorial. The purpose of this study was to estimate the geological and hydraulic properties of the aquifer supplying the well and to determine the water quality of the groundwater from the well. The study provides NPS staff and managers background information for assessing future uses for the well. Methods for data collection and analysis for the study included borehole and video camera analysis in 2020, aquifer testing by the NPS in 2009 and the USGS in 2020, and water-quality sampling in 2020. Borehole camera video generally matched the lithology recorded in the well log. Fractures recorded in the well log and observed with the borehole camera, including more than 20 less prominent fractures and rough sidewall areas, indicated a fractured aquifer. The fractures are the primary conduits for groundwater flow through the rock and into the well. Transmissivity was estimated for the upper and lower water-level drawdown zones at the Burnpit well with data from the NPS and USGS using the Theis and Cooper-Jacob methods. Transmissivity for the NPS test using the Theis method was 9.0 and 11 feet squared per day (ft 2 /d) for the upper and lower drawdown zones, respectively. Using the Cooper-Jacob method, the transmissivity was 22 and 14 ft 2 /d for the upper and lower drawdown zones of the aquifer, respectively. Transmissivity estimates from data from the USGS test were similar. The Theis method, applied to the upper and lower drawdown zones of the aquifer, produced transmissivity estimates of 7.7 and 10 ft 2 /d, and the Cooper-Jacob method produced estimates of 9.7 and 12 ft 2 /d, respectively. Storativity (specific yield) estimated using the Theis method for the NPS aquifer-test data was 0.85 and 0.92 for the upper and lower drawdown zones of the aquifer, respectively. The Cooper-Jacob method applied to the NPS aquifer-test data produced storativity estimates of 0.11 and 0.50 for the upper and lower drawdown zones, respectively. The Theis method applied to the USGS aquifer-test data estimated storativity values of 0.77 and 1.0 for the upper and lower drawdown zones, respectively. The Cooper-Jacob method estimated storativity of 0.50 and 0.60 for the upper and lower drawdown zones of the USGS aquifer test, respectively. The estimated storativity values from the NPS and USGS aquifer tests for the upper and lower drawdown zones were higher than expected for limestones and schists. The hypothetical equilibrium drawdown for the Burnpit well was estimated after the NPS test in 2009 at no more, and possibly less, than 35 gallons per minute. The NPS noted that the sustainable yield likely was overestimated because the water level did not stabilize during the NPS aquifer test. The specific capacity for the NPS aquifer test in 2009 was 0.16 gallon per minute per foot ([gal/min]/ft) of drawdown at 3 hours, and the specific capacity for the USGS aquifer test in 2020 was 0.13 (gal/min)/ft of drawdown at 3 hours. The rate of water-level recovery after pumping ceased was 0.017 and 0.013 (gal/min)/ft for the NPS and USGS aquifer tests, respectively. The water-level recovery rate was nearly an order of magnitude less than the specific capacity estimated during pumping, indicating that water levels in the Burnpit well may not recover quickly enough during pumping to provide for a continuous source of water. Water-quality samples were collected at the Burnpit well on June 24 and July 23, 2020, and analyzed for field-measured properties, major ions, metals, nutrients, and perchlorate. Iron, zinc, and lithium concentrations for unfiltered samples in the well were at least three times greater than the mean filtered sample concentrations reported for crystalline aquifers in the Black Hills. Manganese concentrations were less than the mean concentration for crystalline aquifers but exceeded the U.S. Environmental Protection Agency (EPA) secondary drinking-water standards. The iron concentration from the June 24 sample was about 11 times greater than the EPA secondary drinking-water standards and mean concentrations from crystalline aquifers in the Black Hills. Arsenic concentrations in Burnpit well samples collected in 2020 were greater than the EPA primary drinking-water standard and the mean concentration for crystalline aquifers in the Black Hills. Arsenic occurs naturally in the rock of crystalline aquifers, and concentrations from samples in the Black Hills commonly exceed the EPA primary drinking-water standard of 10 micrograms per liter. High concentrations of arsenic, iron, and manganese metals in the Burnpit well make groundwater from the well in its natural state unusable as a drinking-water source, and water treatment would be necessary to reduce the trace element concentrations to less than the EPA primary and secondary drinking-water standards. However, if the memorial has immediate nonpotable water requirements, such as for construction and fire suppression, groundwater from the Burnpit well could provide water without causing additional stress to current (2021) drinking-water sources.

South Dakota↗
USGS2010

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2003

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2003 (October 1, 2002, to September 30, 2003). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2003 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2003. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 31 cubic feet per second (ft3/s) to the reservoir during WY 2003. For the same time period, annual mean streamflows1 measured (or estimated) for the other monitoring stations in this study ranged from about 0.44 to 20 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,200,000 kilograms (kg) of sodium and 1,900,000 kg of chloride to the Scituate Reservoir during WY 2003; sodium and chloride yields for the tributaries ranged from 10,000 to 61,000 kilograms per square mile (kg/mi2) and from 15,000 to 100,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 21.3 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.06 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 38 and 9 CFU/100 mL (colony forming units per 100 milliliters), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 140 kg/d (67 kg/d/mi2), 15 g/d (6.5 g/d/mi2), 140 g/d (62 g/d/mi2), 340 g/d (180 g/d/mi2), and 2,200 million colony forming units per day (CFU x 106/d) (1,200 CFU x 106/d/mi2) and 940 CFU x 106/d (490 CFU x 106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Rhode Island↗
USGS1973

Ironside Mountain, Oregon: A late Tertiary volcanic and structural enigma

Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement. Ironside Mountain is a 6- by 10-km block of folded rhyolite, andesite, and basalt flows of the Strawberry Volcanics bounded by a horse-shoe-shaped reverse fault and surrounded by Mesozoic rocks. The toe of the horseshoe points northeast; the fault dips outward at angles of 45° to 90°, has a minimum displacement of 600 m at the toe, and dies out or is buried at the open southwest end. Flows are folded to vertical in a crosswise anticline at the northeast end, and in a synclinal structure along the southwest edge. Local unconformities and thickening of flows in a small basin show that some deformation accompanied volcanism, which has been dated as late Miocene and early Pliocene. No centers of eruption have been identified within the Horseshoe fault. The Ironside Mountain block seems to be a unique expression of cross folding in the region. The northwest-striking Mine Ridge–Ironside anticline follows the main regional trend, and is faulted where two large down-warps strike into it from the northeast. The Ironside Mountain structure is interpreted as being a transverse compressional feature in which opposing reverse faults took the place of anticlinal folding, directly on strike with a syncline to the northeast. A horst of pre-Tertiary rocks, which has been raised at least 600 m, crosses the axes of the abutting structures; the nose of the Horseshoe fault bounds one side of it, and a range-border fault bounds the other. Cross faults, of which we found only one, are believed to have facilitated arching and longitudinal shortening within the horst.

Oregon↗
USGS1990

Stratigraphy and tectonics of Paleozoic arc-related rocks of the northernmost Sierra Nevada, California; The eastern Klamath and northern Sierra terranes

The Eastern Klamath and Northern Sierra terranes of northern California consist of Devonian to Jurassic arc-related rocks that structurally and/or stratigraphically overlie Devonian(?) or older complexes that consist of quartzite, quartzofeldspathic sandstone, chert, and mafic and ultramafic rocks. These terranes lie within a regional belt of Paleozoic arc-related rocks that can be recognized from the Sierra Nevada to British Columbia. The Eastern Klamath and Northern Sierra terranes are geographically separate and have paleontologic linkage, but lack direct stratigraphic ties in strata of Late Devonian to Early Permian age. This chapter describes new stratigraphic correlations and structural interpretations of rocks that lie in the northernmost part of the Sierra Nevada. These rocks include the Butt Valley block of the Northern Sierra terrane, and rocks herein interpreted as dismembered Eastern Klamath terrane. The rocks of Eastern Klamath terrane affinity, Soda Ravine block, occur as a tectonic sliver that lies to the west of the Butt Valley block. The Soda Ravine block is about 2 to 4 km by 20 km and includes limestone lenses equivalent to zone A of the McCloud Limestone of the Eastern Klamath terrane, and upper Middle and Upper Triassic limestone, slate, siltstone, and pebble conglomerate. Similar Permian limestone with McCloud faunal affinities and slate-bearing slivers have been noted by previous workers in this area and to the south. The Butt Valley block had previously been interpreted as part of the west limb of a regional anticline, the Almanor anticline. New mapping suggests that the block is not contiguous with rocks that lie to the east. The Butt Valley block includes the Devonian and Mississippian Taylor Formation, which is unconformably overlain by an Upper Triassic (Carnian and Norian) basal conglomerate and sandstone, which in turn is overlain by Upper Triassic limestone. The Upper Triassic limestone is overlain by a sparsely fossiliferous, lithic-volcaniclastic sequence containing poorly preserved Triassic or Early Jurassic, and probable Early Jurassic, ammonites and clams. This sequence is similar to conglomerate, Triassic limestone, and volcaniclastic rocks of the Jurassic Sailor Canyon Formation, which overlie a regional Late Triassic unconformity west of Lake Tahoe, thus expanding the known distribution of the unconformity in the Sierra Nevada. The Triassic unconformity overlies Carboniferous and older rocks around the North Fork American River area to the south, and overlies Devonian and older rocks on the Butt Valley block, but overlies Permian rocks east and southeast of the Butt Valley block. These relations suggest that either the Butt Valley block was part of a highland or uplifted block along the western part of the northern Sierra terrane or that the Butt Valley block previously lay closer to the North Fork American River area and has been translated northward by right-slip displacement. Northern Sierra terrane east of the Butt Valley block consists of the Hough and Genesse blocks, which are separated by the Grizzly Mountain fault zone. The Grizzly Mountain fault zone is here interpreted to be a transpressional right-slip fault.

California↗
USGS2009

Implementation of the SSHAC Guidelines for Level 3 and 4 PSHAs - Experience gained from actual applications

In April 1997, after four years of deliberations, the Senior Seismic Hazard Analysis Committee released its report 'Recommendations for Probabilistic Seismic Hazard Analysis: Guidance on Uncertainty and Use of Experts' through the U.S. Nuclear Regulatory Commission as NUREG/CR-6372, hereafter SSHAC (1997). Known informally ever since as the 'SSHAC Guidelines', SSHAC (1997) addresses why and how multiple expert opinions - and the intrinsic uncertainties that attend them - should be used in Probabilistic Seismic Hazard Analyses (PSHA) for critical facilities such as commercial nuclear power plants. Ten years later, in September 2007, the U.S. Geological Survey (USGS) entered into a 13-month agreement with the U.S. Nuclear Regulatory Commission (NRC) titled 'Practical Procedures for Implementation of the SSHAC Guidelines and for Updating PSHAs'. The NRC was interested in understanding and documenting lessons learned from recent PSHAs conducted at the higher SSHAC Levels (3 and 4) and in gaining input from the seismic community for updating PSHAs as new information became available. This study increased in importance in anticipation of new applications for nuclear power facilities at both existing and new sites. The intent of this project was not to replace the SSHAC Guidelines but to supplement them with the experience gained from putting the SSHAC Guidelines to work in practical applications. During the course of this project, we also learned that updating PSHAs for existing nuclear power facilities involves very different issues from the implementation of the SSHAC Guidelines for new facilities. As such, we report our findings and recommendations from this study in two separate documents, this being the first. The SSHAC Guidelines were written without regard to whether the PSHAs to which they would be applied were site-specific or regional in scope. Most of the experience gained to date from high-level SSHAC studies has been for site-specific cases, although three ongoing (as of this writing) studies are regional in scope. Updating existing PSHAs will depend more critically on the differences between site-specific and regional studies, and we will also address these differences in more detail in the companion report. Most of what we report here and in the second report on updating PSHAs emanates from three workshops held by the USGS at their Menlo Park facility: 'Lessons Learned from SSHAC Level 3 and 4 PSHAs' on January 30-31, 2008; 'Updates to Existing PSHAs' on May 6-7, 2008; and 'Draft Recommendations, SSHAC Implementation Guidance' on June 4-5, 2009. These workshops were attended by approximately 40 scientists and engineers familiar with hazard studies for nuclear facilities. This company included four of the authors of SSHAC (1997) and four other experts whose contributions to this document are mentioned in the Acknowledgments section; numerous scientists and engineers who in one role or another have participated in one or more high-level SSHAC PSHAs summarized later in this report; and representatives of the nuclear industry, the consulting world, the regulatory community, and academia with a keen interest and expertise in hazard analysis. This report is a community-based set of recommendations to NRC for improved practical procedures for implementation of the SSHAC Guidelines. In an early publication specifically addressing the SSHAC Guidelines, Hanks (1997) noted that the SSHAC Guidelines were likely to evolve for some time to come, and this remains true today. While the broad philosophical and theoretical dimensions of the SSHAC Guidelines will not change, much has been learned during the past decade from various applications of the SSHAC Guidelines to real PSHAs in terms of how they are implemented. We anticipate that, in their practical applications, the SSHAC Guidelines will continue to evolve as more experience is gained from future SSHAC applications. Indeed, to the extent that every PSHA has its

Open-File Report↗
USGS2010

Streamflow, Water Quality, and Constituent Loads and Yields, Scituate Reservoir Drainage Area, Rhode Island, Water Year 2005

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board, Rhode Island’s largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 10 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate instantaneous (15-minute) loads of sodium and chloride during water year (WY) 2005 (October 1, 2004, to September 30, 2005). Water-quality samples were also collected at 37 sampling stations in the Scituate Reservoir drainage area by the Providence Water Supply Board during WY 2005 as part of a long-term sampling program. Water-quality data are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2005. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed about 30 cubic feet per second (ft 3 /s) to the reservoir during WY 2005. For the same time period, annual mean streamflows1 measured (or estimated) for the other monitoring stations in this study ranged from about 0.42 to 19 ft 3 /s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,300,000 kilograms (kg) of sodium and 2,000,000 kg of chloride to the Scituate Reservoir during WY 2005; sodium and chloride yields for the tributaries ranged from 13,000 to 77,000 kilograms per square mile (kg/mi 2 ) and from 19,000 to 130,000 kg/mi 2 , respectively. At the stations where water-quality samples were collected by the Providence Water Supply Board, the median of the median chloride concentrations was 25.3 milligrams per liter (mg/L), median nitrite concentration was 0.002 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.07 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 23 and 15 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 230 kg/d (93 kg/d/mi 2 ), 16 g/d (6.1 g/d/mi 2 ), 150 g/d (71 g/d/mi 2 ), 530 g/d (250 g/d/mi 2 ), and 1,500 million colony forming units per day (CFU×106/d) (630 CFU×106/d/mi 2 ) and 420 CFU×106/d (290 CFU×106/d/mi 2 ), respectively. 1 The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Rhode Island↗
USGS2010

Streamflow, water quality, and constituent loads and yields, Scituate Reservoir drainage area, Rhode Island, water year 2009

Streamflow and water-quality data were collected by the U.S. Geological Survey (USGS) or the Providence Water Supply Board (PWSB), Rhode Island's largest drinking-water supplier. Streamflow was measured or estimated by the USGS following standard methods at 23 streamgage stations; 13 of these stations were also equipped with instrumentation capable of continuously monitoring specific conductance and water temperature. Streamflow and concentrations of sodium and chloride estimated from records of specific conductance were used to calculate loads of sodium and chloride during water year (WY) 2009 (October 1, 2008, to September 30, 2009). Water-quality samples also were collected at 37 sampling stations by the PWSB and at 14 monitoring stations by the USGS during WY 2009 as part of a long-term sampling program; all stations are in the Scituate Reservoir drainage area. Water-quality data collected by PWSB are summarized by using values of central tendency and are used, in combination with measured (or estimated) streamflows, to calculate loads and yields (loads per unit area) of selected water-quality constituents for WY 2009. The largest tributary to the reservoir (the Ponaganset River, which was monitored by the USGS) contributed a mean streamflow of about 27 cubic feet per second (ft3/s) to the reservoir during WY 2009. For the same time period, annual mean1 streamflows measured (or estimated) for the other monitoring stations in this study ranged from about 0.50 to 17 ft3/s. Together, tributary streams (equipped with instrumentation capable of continuously monitoring specific conductance) transported about 1,400,000 kilograms (kg) of sodium and 2,200,000 kg of chloride to the Scituate Reservoir during WY 2009; sodium and chloride yields for the tributaries ranged from 10,000 to 64,000 kilograms per square mile (kg/mi2) and from 15,000 to 110,000 kg/mi2, respectively. At the stations where water-quality samples were collected by the PWSB, the median of the median chloride concentrations was 21.7 milligrams per liter (mg/L), median nitrite concentration was 0.001 mg/L as N, median nitrate concentration was 0.02 mg/L as N, median orthophosphate concentration was 0.09 mg/L as P, and median concentrations of total coliform and Escherichia coli (E. coli) bacteria were 61 and 16 colony forming units per 100 milliliters (CFU/100 mL), respectively. The medians of the median daily loads (and yields) of chloride, nitrite, nitrate, orthophosphate, and total coliform and E. coli bacteria were 190 kg/d (61 kg/d/mi2), 12 g/d (4.5 g/d/mi2), 93 g/d (32 g/d/mi2), 420 g/d (290 g/d/mi2), 6,200 million colony forming units per day (CFU?106/d) (2,600 CFU?106/d/mi2), and 1,100 CFU?106/d (340 CFU?106/d/mi2), respectively. 1The arithmetic mean of the individual daily mean discharges for the year noted or for the designated period.

Open-File Report↗