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At least 1,207 records · Page 67Linked to original sources
USGS1981

Thermodynamic tabulations for selected phases in the system CaO-Al 2 O 3 -SiO 2 -H 2 at 101.325 kPa (1 atm) between 273.15 and 1800 K

The standard thermodynamic properties of phases in the lime‐alumina‐silica‐ water system between 273.15 and 1800 K at 101.325 kPa (1 atm) were evalated from published experimental data. Phases included in the compilation are boehmite, diaspore, gibbsite, kaolinite, dickite, halloysite, andalusite, kyanite, sillimanite, Ca‐Al cliniopyroxene, anorthite, gehlenite, grossular, prehnite, zoisite, margarite, wollastonite, cyclowollastonite ( = pseudowollastonite), larnite, Ca olivine, hatrurite, and rankinite. The properties include heat capacity, entropy, relative enthalpy, and the Gibbs energy function of the phases and the enthalpies, Gibbs energies, and equilibrium constants for formation both from the elements and the oxides. Tabulated values are given at 50 K intervals with the 2‐sigma confidence limit at 250 K intervals. Summaries for each phase give the temperature‐ dependent functions for heat capacity, entropy, and relative enthalpy and the experimental data used in the final evaluation.

Journal of Physical and Chemical Reference Data↗
USGS2010

An analysis of the carbon balance of the Arctic Basin from 1997 to 2006

This study used several model-based tools to analyse the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr -1 and that the Arctic Ocean gained 94.1 Tg C yr -1 . Arctic lands and oceans were a net CO 2 sink of 108.9 Tg C yr -1 , which is within the range of uncertainty in estimates from atmospheric inversions. Although both lands and oceans of the Arctic were estimated to be CO 2 sinks, the land sink diminished in strength because of increased fire disturbance compared to previous decades, while the ocean sink increased in strength because of increased biological pump activity associated with reduced sea ice cover. Terrestrial areas of the Arctic were a net source of 41.5 Tg CH 4 yr -1 that increased by 0.6 Tg CH 4 yr -1 during the decade of analysis, a magnitude that is comparable with an atmospheric inversion of CH 4 . Because the radiative forcing of the estimated CH 4 emissions is much greater than the CO 2 sink, the analysis suggests that the Arctic Basin is a substantial net source of green house gas forcing to the climate system.

Tellus, Series B: Chemical and Physical Meteorolog↗
USGS2014

230Th/U ages Supporting Hanford Site‐Wide Probabilistic Seismic Hazard Analysis

This product represents a USGS Administrative Report that discusses samples and methods used to conduct uranium-series isotope analyses and resulting ages and initial 234U/238U activity ratios of pedogenic cements developed in several different surfaces in the Hanford area middle to late Pleistocene. Samples were collected and dated to provide calibration of soil development in surface deposits that are being used in the Hanford Site-Wide probabilistic seismic hazard analysis conducted by AMEC. The report includes description of sample locations and physical characteristics, sample preparation, chemical processing and mass spectrometry, analytical results, and calculated ages for individual sites. Ages of innermost rinds on a number of samples from five sites in eastern Washington are consistent with a range of minimum depositional ages from 17 ka for cataclysmic flood deposits to greater than 500 ka for alluvium at several sites.

Washington↗
USGS1973

Water facts and figures for planners and managers

Water is defined in terms of its chemical composition and dominant physical properties, such as expansion on freezing and high surface tension. Water on the earth is about 97 percent in the seas, 2 percent in glacier ice, principally Greenland and Antarctica. Man is left with less than 1 percent as liquid fresh water to sustain his needs. This is possible under good management because water moves cyclically. Conjunctive use of surface and ground water is advocated, as is reuse of wastewater. Water needs for domestic and light industrial use can be reasonably forecast for planning purposes. Heavy-industry needs must be determined on a site-by-site basis. The units commonly used by hydrologists with respect to quantities and quality of water are denned; their significance in water management is outlined, and metric-english equivalents are given for many. A glossary of terms concludes the report which is intended as a reference work for use by planners and managers.

Circular↗
USGS2015

Hydrologic data for the Walker River Basin, Nevada and California, water years 2010–14

Walker Lake is a threatened and federally protected desert terminal lake in western Nevada. To help protect the desert terminal lake and the surrounding watershed, the Bureau of Reclamation and U.S. Geological Survey have been studying the hydrology of the Walker River Basin in Nevada and California since 2004. Hydrologic data collected for this study during water years 2010 through 2014 included groundwater levels, surface-water discharge, water chemistry, and meteorological data. Groundwater levels were measured in wells, and surface-water discharge was measured in streams, canals, and ditches. Water samples for chemical analyses were collected from wells, streams, springs, and Walker Lake. Chemical analyses included determining physical properties; the concentrations of major ions, nutrients, trace metals, dissolved gases, and radionuclides; and ratios of the stable isotopes of hydrogen and oxygen. Walker Lake water properties and meteorological parameters were monitored from a floating platform on the lake. Data collection methods followed established U.S. Geological Survey guidelines, and all data are stored in the National Water Information System database. All of the data are presented in this report and accessible on the internet, except multiple-depth Walker Lake water-chemistry data, which are available only in this report.

California, Nevada↗
USGS2009

Questa Baseline and Pre-mining Ground-Water Quality Investigation, 7. A Pictorial Record of Chemical Weathering, Erosional Processes, and Potential Debris-flow Hazards in Scar Areas Developed on Hydrothermally Altered Rocks

Erosional scar areas developed along the lower Red River basin, New Mexico, reveal a complex natural history of mineralizing processes, rapid chemical weathering, and intense physical erosion during periodic outbursts of destructive, storm-induced runoff events. The scar areas are prominent erosional features with craggy headwalls and steep, denuded slopes. The largest scar areas, including, from east to west, Hottentot Creek, Straight Creek, Hansen Creek, Lower Hansen Creek, Sulfur Gulch, and Goat Hill Gulch, head along high east-west trending ridges that form the northern and southern boundaries of the lower Red River basin. Smaller, topographically lower scar areas are developed on ridge noses in the inner Red River valley. Several of the natural scar areas have been modified substantially as a result of large-scale open-pit and underground mining at the Questa Mine; for example, much of the Sulfur Gulch scar was removed by open pit mining, and several scars are now partially or completely covered by mine waste dumps.

Open-File Report↗
USGS2011

Suspended sediment and organic contaminants in the San Lorenzo River, California, water years 2009-2010

This report presents analyses of suspended sediment and organic contaminants measured during a two-year study of the San Lorenzo River, central California, which discharges into the Pacific Ocean within the Monterey Bay National Marine Sanctuary. Most suspended-sediment transport occurred during flooding caused by winter storms; 55 percent of the sediment load was transported by the river during a three-day flood in January 2010. Concentrations of polyaromatic hydrocarbons can exceed regulatory criteria during high-flow events in the San Lorenzo River. These results highlight the importance of episodic sediment and contaminant transport in steep, mountainous, coastal watersheds and emphasize the importance of understanding physical processes and quantifying chemical constituents in discharge from coastal watersheds on event-scale terms.

Open-File Report↗
USGS1994

Report of the Interagency biological methods workshop

The U.S. Geological Survey hosted the Interagency Biological Methods Workshop in Reston, Virginia, during June 22-23, 1993. The purposes of the workshop were to (1) promote better communication among Federal agencies that are using or developing biological methods in water-quality assessment programs for streams and rivers, and (2) facilitate the sharing of data and interagency collaboration. The workshop was attended by 45 biologists representing numerous Federal agencies and programs, and a few regional and State programs that were selected to provide additional perspectives. The focus of the workshop was community assessment methods for fish, invertebrates, and algae; physical habitat characterization; and chemical analyses of biological tissues. Charts comparing program objectives, design features, and sampling methods were compiled from materials that were provided by participating agencies prior to the workshop and formed the basis for small workgroup discussions. Participants noted that differences in methods among programs were often necessitated by differences in program objectives. However, participants agreed that where programs have identified similar data needs, the use of common methods is beneficial. Opportunities discussed for improving data compatibility and information sharing included (1) modifying existing methods, (2) adding parameters, (3) improving access to data through shared databases (potentially with common database structures), and (4) future collaborative efforts that range from research on selected protocol questions to followup meetings and continued discussions.

Open-File Report↗
USGS2012

Water-quality assessment and macroinvertebrate data for the Upper Yampa River watershed, Colorado, 1975 through 2009

A study was initiated in 2009 by the U.S. Geological Survey (USGS), in cooperation with Routt County, the Colorado Water Conservation Board, and the City of Steamboat Springs, to compile and analyze historic water-quality data and assess water-quality conditions in the Upper Yampa River watershed (UYRW) in northwestern Colorado. Water-quality data for samples collected by federal, state, and local agencies for various periods from 1975 through 2009 were compiled and assessed for streams, lakes, reservoirs, and groundwater in the UYRW, including the Elkhead Creek subwatershed and the Yampa River watershed that is upstream from Elkhead Creek. For selected physical-property and chemical-constituent data for samples collected from surface-water sites and groundwater wells in the UYRW, this report: (1) characterizes available data through statistical summaries, (2) analyzes the spatial and temporal distribution of water-quality conditions, (3) identifies temporal trends in water quality, where possible, (4) provides comparisons to federal and state water-quality standards and recommendations, and (5) identifies factors affecting the quality of water. In addition, the availability and characteristics of macroinvertebrate data collected in the UYRW are described.

Colorado↗
USGS1991

Geohydrology and quality of water in aquifers in Lucas, Sandusky, and Wood counties, northwestern Ohio

The hydrology and quality of ground water were evaluated for the surficial sand and carbonate aquifers in northwestern Ohio. A locally important surficial sand aquifer in western Lucas County was evaluated on the basis of data from 10 wells completed in undeveloped and developed areas. The carbonate aquifer in Silurian and Devonian bedrock at its northernmost extent on the Ohio mainland was evaluated on the basis of data from previous studies and data from 466 wells and 11 springs. Most data are for the period 1985-88. The unconfined surficial sand aquifer is less than 50 ft. (feet) thick. Clay-rich drift, which restricts vertical movement of water, underlines the aquifer. Recharge is from precipitation, and discharge is by evapotranspiration and by flow to local streams and drainage ditches. Water levels are generally 2 to 8 ft. below land surface and fluctuate a total of about 3.5 ft. seasonally in a forested area. Concentrations of iron and manganese in ground water are excessive in some areas. Waters from shallow drive-point wells in residential areas contained larger concentrations of dissolved solids, hardness, sodium, and chloride than did waters from identical wells in undeveloped areas. The presence of nitrate nitrogen an other selected constituents in ground water in residential areas, and the absence of these constituents in ground water in undeveloped areas, indicate that the surficial sand aquifer has been affected by development. In carbonate aquifer, fractures, bedding-plane joints, and other secondary openings are the principal water-bearing zones. These zones can be areally and stratigraphically separated by low-permeability rock. Leaky artesian or semiconfined conditions predominate beneath most of the 1,400-mi? study area. The aquifer is confined by relatively impermeable underlying shale of Silurian age and overlying clay-rich drift of Quaternary age. Unproductive strata, including evaporites, within the sequence of carbonate rocks also confine some water-bearing zones. The carbonate aquifer is part of a regional ground-water-flow system; however, subsystems such as the eastern karst and central outcrops are locally important. The potentiometric surface indicates that recharge from areas south and west of the study area flows toward discharge areas along major rivers (Maumee, Portage, and Sandusky) , to a buried bedrock valley in central Sandusky County, and to springs and flowing wells. The potentiometric surface flattens markedly near the southern shore of Lake Erie, where ground-water levels approximate those of the lake, indicating a hydraulic connection between the lake and the aquifer. Hydrogeologic characteristics and water-quality data indicate that Lake Erie is not a major source of recharge to the aquifer. Ground-water ages inferred from tritium concentrations and potentiometric-surface maps indicate that recharge from precipitation enters the aquifer by subsurface drainage in karstified strata in eastern Sandusky County and by infiltration in shallow bedrock areas where drift is less than 20 ft. thick. The quality of water in the carbonate aquifer is described with reference to 52 properties and constituents that characterize chemical, radiochemical, bacteriologic, and physical conditions. Ground-water samples from 135 wells and 11 springs are used in the characterization. On the basis of these data, water from the aquifer is generally suitable for drinking and for most domestic purposes. The most areally widespread aesthtic factors limiting the use of ground water are hardness, concentrations of dissolved solids, sulfate and iron, and the presence of hydrogen sulfide. Selected bacteria are commonly present and may compromise the potability of water from the aquifer. Coliform bacteria from surface sources were found in 47 of 143 water samples. Analyses for total coliform bacteria indicate that 36 of the 125 samples from wells maintained for potable supply have bacteria counts of 4

Water-Resources Investigations Report↗
USGS1998

Seasonal and interannual variations of atmospheric CO2 and climate

Interannual variations of atmospheric CO 2 concentrations at Mauna Loa are almost masked by the seasonal cycle and a strong trend; at the South Pole, the seasonal cycle is small and is almost lost in the trend and interannual variations. Singular-spectrum analysis (SSA) is used here to isolate and reconstruct interannual signals at both sites and to visualize recent decadal changes in the amplitude and phase of the seasonal cycle. Analysis of the Mauna Loa CO 2 series illustrates a hastening of the CO 2 seasonal cycle, a close temporal relation between Northern Hemisphere (NH) mean temperature trends and the amplitude of the seasonal CO 2 cycle, and tentative ties between the latter and seasonality changes in temperature over the NH continents. Variations of the seasonal CO 2 cycle at the South Pole differ from those at Mauna Loa: it is phase changes of the seasonal cycle at the South Pole, rather than amplitude changes, that parallel hemispheric and global temperature trends. The seasonal CO 2 cycles exhibit earlier occurrences of the seasons by 7 days at Mauna Loa and 18 days at the South Pole. Interannual CO 2 variations are shared at the two locations, appear to respond to tropical processes, and can be decomposed mostly into two periodicities, around (3 years) -1 and (4 years) -1 , respectively. Joint SSA analyses of CO 2 concentrations and tropical climate indices isolate a shared mode with a quasi-triennial (QT) period in which the CO 2 and sea-surface temperature (SST) participation are in phase opposition. The other shared mode has a quasi-quadrennial (QQ) period and CO 2 variations are in phase with the corresponding tropical SST variations throughout the tropics. Together these interannual modes exhibit a mean lag between tropical SSTs and CO 2 variations of about 6–8 months, with SST leading. Analysis of the QT and QQ signals in global gridded SSTs, joint SSA of CO 2 and δ13C isotopic ratios, and SSA of CO 2 and NH-land temperatures indicate that the QT variations in CO 2 mostly reflect upwelling variations in the eastern tropical Pacific. QQ variations are dominated by the CO 2 signature of terrestrial-ecosystem response to global QQ climate variations. Climate variations associated with these two interannual components of tropical variability have very different effects on global climate and, especially, on terrestrial ecosystems and the carbon cycle.

Tellus, Series B: Chemical and Physical Meteorolog↗
USGS1999

A first-order analysis of the potential role of CO2 fertilization to affect the global carbon budget: A comparison of four terrestrial biosphere models

We compared the simulated responses of net primary production, heterotrophic respiration, net ecosystem production and carbon storage in natural terrestrial ecosystems to historical (1765 to 1990) and projected (1990 to 2300) changes of atmospheric CO2 concentration of four terrestrial biosphere models: the Bern model, the Frankfurt Biosphere Model (FBM), the High-Resolution Biosphere Model (HRBM) and the Terrestrial Ecosystem Model (TEM). The results of the model intercomparison suggest that CO2 fertilization of natural terrestrial vegetation has the potential to account for a large fraction of the so-called 'missing carbon sink' of 2.0 Pg C in 1990. Estimates of this potential are reduced when the models incorporate the concept that CO2 fertilization can be limited by nutrient availability. Although the model estimates differ on the potential size (126 to 461 Pg C) of the future terrestrial sink caused by CO2 fertilization, the results of the four models suggest that natural terrestrial ecosystems will have a limited capacity to act as a sink of atmospheric CO2 in the future as a result of physiological constraints and nutrient constraints on NPP. All the spatially explicit models estimate a carbon sink in both tropical and northern temperate regions, but the strength of these sinks varies over time. Differences in the simulated response of terrestrial ecosystems to CO2 fertilization among the models in this intercomparison study reflect the fact that the models have highlighted different aspects of the effect of CO2 fertilization on carbon dynamics of natural terrestrial ecosystems including feedback mechanisms. As interactions with nitrogen fertilization, climate change and forest regrowth may play an important role in simulating the response of terrestrial ecosystems to CO2 fertilization, these factors should be included in future analyses. Improvements in spatially explicit data sets, whole-ecosystems experiments and the availability of net carbon exchange measurements across the globe will also help to improve future evaluations of the role of CO2 fertilization on terrestrial carbon storage.

Tellus, Series B: Chemical and Physical Meteorolog↗
USGS1989

Appalachian Piedmont landscapes from the Permian to the Holocene

Between the Potomac and Susquehanna Rivers and from the Blue Ridge to the Fall Zone, landscapes of the Piedmont are illustrated for times in the Holocene, Late Wisconsin, Early Miocene, Early Cretaceous, Late Triassic, and Permian. Landscape evolution took place in tectonic settings marked by major plate collisions (Permian), arching and rifting (Late Triassic) and development of the Atlantic passive margin by sea floor spreading (Early Cretaceous). Erosion proceeded concurrently with tectonic uplift and continued after cessation of major tectonic activity. Atlantic Outer Continental Shelf sediments record three major erosional periods: (1) Late Triassic-Early Jurassic; (2) Late Jurassic-Early Cretaceous; and (3) Middle Miocene-Holocene. The Middle Miocene-Holocene pulse is related to neotectonic activity and major climatic fluctuations. In the Piedmont upland the Holocene landscape is interpreted as an upland surface of low relief undergoing dissection. Major rivers and streams are incised into a landscape on which the landforms show a delicate adjustment to rock lithologies. The Fall Zone has apparently evolved from a combination of warping, faulting, and differential erosion since Late Miocene. The periglacial environment of the Late Wisconsin (and earlier glacial epochs) resulted in increased physical erosion and reduced chemical weathering. Even with lowered saprolitization rates, geochemical modeling suggests that 80 m or more of saprolite may have formed since Late Miocene. This volume of saprolite suggests major erosion of upland surfaces and seemingly contradicts available field evidence. Greatly subdued relief characterized the Early Miocene time, near the end of a prolonged interval of tropical morphogenesis. The ancestral Susquehanna and Potomac Rivers occupied approximately their present locations. In Early Cretaceous time local relief may have been as much as 900 m, and a major axial river draining both the Piedmont and Appalachians flowed southeast past Baltimore. The Late Triassic landscape was influenced by rift basin development. Streams drained into a hydrologically closed basin: no through-flowing rivers seem to have been present. A limestone escarpment along the Blue Ridge may have existed as a consequence of a semi-arid climate. The Permian may have been a time of Himalayan-like mountains and mountain glaciers. Streams (and glaciers) generally flowed southwest and west. ?? 1989.

Geomorphology↗
USGS2005

Risk analysis for biological hazards: What we need to know about invasive species

Risk analysis for biological invasions is similar to other types of natural and human hazards. For example, risk analysis for chemical spills requires the evaluation of basic information on where a spill occurs; exposure level and toxicity of the chemical agent; knowledge of the physical processes involved in its rate and direction of spread; and potential impacts to the environment, economy, and human health relative to containment costs. Unlike typical chemical spills, biological invasions can have long lag times from introduction and establishment to successful invasion, they reproduce, and they can spread rapidly by physical and biological processes. We use a risk analysis framework to suggest a general strategy for risk analysis for invasive species and invaded habitats. It requires: (1) problem formation (scoping the problem, defining assessment endpoints); (2) analysis (information on species traits, matching species traits to suitable habitats, estimating exposure, surveys of current distribution and abundance); (3) risk characterization (understanding of data completeness, estimates of the “potential” distribution and abundance; estimates of the potential rate of spread; and probable risks, impacts, and costs); and (4) risk management (containment potential, costs, and opportunity costs; legal mandates and social considerations and information science and technology needs).

Risk Analysis↗
USGS2016

The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam Onboard Curiosity

The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K 2 O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K 2 O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

Journal of Geophysical Research↗
USGS2012

Feeding response of sport fish after electrical immobilization, chemical sedation, or both

Fishery managers frequently capture wild fish for a variety of fishery management activities. Though some activities can be accomplished without immobilizing the fish, others are accomplished more readily, humanely, and safely (for both the handler and the fish) when fish are immobilized by physical (e.g., electrical immobilization) or chemical sedation. A concern regarding the use of chemical sedatives is that chemical residues may remain in the fillet tissue after the fish recovers from sedation. If those residues are harmful to humans, there is some risk that a postsedated fish released to public waters may be caught and consumed by an angler. To characterize this risk, a series of four trials were conducted. Three trials assessed feeding activity after hatchery-reared fish were electrically immobilized, chemically sedated, or both, and one trial assessed the likelihood of an angler catching a wild fish that had been electrically immobilized and chemically sedated. Results from the first trial indicated that the feeding activity of laboratory habituated fish was variable among and within species after electrical immobilization, chemical sedation, or both. Results from the second trial indicated that the resumption of feeding activity was rapid after being mildly sedated for 45 min. Results from the third trial indicated that the feeding activity of outdoor, hatchery-reared fish was relatively aggressive after fish had been chemically sedated. Results from the fourth trial indicated that the probability of capturing wild fish in a more natural environment by angling after fish had been electrically immobilized and chemically sedated is not likely, i.e., in a group of five fish caught, 3 out of 100 times one would be a fish that had been sedated.

North American Journal of Fisheries Management↗
USGS1996

Reactive solute transport in streams: 1. Development of an equilibrium- based model

An equilibrium-based solute transport model is developed for the simulation of trace metal fate and transport in streams. The model is formed by coupling a solute transport model with a chemical equilibrium submodel based on MINTEQ. The solute transport model considers the physical processes of advection, dispersion, lateral inflow, and transient storage, while the equilibrium submodel considers the speciation and complexation of aqueous species, precipitation/dissolution and sorption. Within the model, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (water-borne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach.

Water Resources Research↗
USGS1987

Index of surface-water stations in Texas, January 1987

As of January 1, 1987, the surface-water data-collection network in Texas included 376 continuous streamflow, 76 continuous or daily reservoir-content, 34 gage height, 16 crest-stage partial-record, 8 periodic discharge through range, 33 floodhydrograph partial-record, 9 flood-profile partial-record, 36 low-flow partial-record, 46 daily chemical-quality, 19 continuous-recording water-quality, 84 periodic biological, 17 lake surveys, 162 periodic organic and (or) nutrient, 3 periodic insecticide, 42 periodic pesticide, 19 automatic sampler, 141 periodic minor elements, 130 periodic chemical-quality, 78 periodic physical-organic, 22 continuous-recording three- or four-parameter water-quality, 34 periodic sediment, 22 continuous-recording temperature, and 30 national stream-quality accounting network stations. Plate 1 shows the location of surface-water streamflow or reservoir-content and chemical-quality or sediment'stations in Texas. Plate 2 shows the location of partial-record surfacewater stations. This index shows the station number and name, latitude and longitude, type of data collected, and the office principally responsible for the data collection (table 1). An 8-digit permanent numerical designation for gaging stations has been adopted on a nationwide basis; stations are numbered and listed in downstream order. In the downstream direction along the main stem, all stations on a tributary entering above a main-stem station are listed before that station. A tributary entering between two main-stem stations is listed between them. A similar order is followed in listing stations on first rank, second rank, and other ranks of tributaries. To indicate the rank of any tributary on which a gaging station is situated and the stream to which it is an immediate tributary, each indention in the listing of gaging stations represent one rank. This downstream order and system of indention show which gaging stations are on tributaries between any two stations on a main stem and the rank of the tributary on which each gaging station is situated. On plates 1 and 2, the 8-digit station number is abbreviated because of space limitation.

Texas↗