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At least 1,243 records · Page 69Linked to original sources
USGS1978

Hydrologic Unit Map-1978, state of South Dakota

This map and accompanying table show Hydrologic Unites that are basically hydrographic in nature. The Cataloging Unites shown supplant the Cataloging Units previously depicted n the 1974 State Hydrologic Unit Map. The boundaries as shown have been adapted from the 1974 State Hydrologic Unit Map, "The Catalog of Information on Water Data" (1972), "Water Resources Regions and Subregions for the National Assessment of Water and Related Land Resources" by the U.S. Water Resources Council (1970), "River Basin of the United States" by the U.S. Soil Conservation Service (1963, 1970), "River Basin Maps Showing Hydrologic Stations" by the Inter-Agency Committee on Water Resources, Subcommittee on Hydrology (1961), and State planning maps. The Political Subdivision has been adopted from "Counties and County Equivalents of the States if the United States" presented in Federal Information Processing Standards Publication 6-2, issued by the National Bureau of Standards (1973) in which each county or county equivalent is identified by a 2-character State code and a 3-character county code. The Regions, Subregions and Accounting Units are aggregates of the Cataloging Unites. The Regions and Sub regions are currently (1978) used by the U.S> Water Resources Council for comprehensive planning, including the National Assessment, and as a standard geographical framework for more detailed water and related land-resources planning. The Accounting Units are those currently (1978) in use by the U.S. Geological Survey for managing the National Water Data Network. This map was revised to include a boundary realinement between Cataloging Units 10140103 and 10160009.

South Dakota↗
USGS2003

Hydrogeology and Simulated Effects of Ground-Water Withdrawals in the Big River Area, Rhode Island

The Rhode Island Water Resources Board is considering expanded use of ground-water resources from the Big River area because increasing water demands in Rhode Island may exceed the capacity of current sources. This report describes the hydrology of the area and numerical simulation models that were used to examine effects of ground-water withdrawals during 1964?98 and to describe potential effects of different withdrawal scenarios in the area. The Big River study area covers 35.7 square miles (mi2) and includes three primary surface-water drainage basins?the Mishnock River Basin above Route 3, the Big River Basin, and the Carr River Basin, which is a tributary to the Big River. The principal aquifer (referred to as the surficial aquifer) in the study area, which is defined as the area of stratified deposits with a saturated thickness estimated to be 10 feet or greater, covers an area of 10.9 mi2. On average, an estimated 75 cubic feet per second (ft3/s) of water flows through the study area and about 70 ft3/s flows out of the area as streamflow in either the Big River (about 63 ft3/s) or the Mishnock River (about 7 ft3/s). Numerical simulation models are used to describe the hydrology of the area under simulated predevelopment conditions, conditions during 1964?98, and conditions that might occur in 14 hypothetical ground-water withdrawal scenarios with total ground-water withdrawal rates in the area that range from 2 to 11 million gallons per day. Streamflow depletion caused by these hypothetical ground-water withdrawals is calculated by comparison with simulated flows for the predevelopment conditions, which are identical to simulated conditions during the 1964?98 period but without withdrawals at public-supply wells and wastewater recharge. Interpretation of numerical simulation results indicates that the three basins in the study area are in fact a single ground-water resource. For example, the Carr River Basin above Capwell Mill Pond is naturally losing water to the Mishnock River Basin. Withdrawals in the Carr River Basin can deplete streamflows in the Mishnock River Basin. Withdrawals in the Mishnock River Basin deplete streamflows in the Big River Basin and can intercept water flowing to the Flat River Reservoir North of Hill Farm Road in Coventry, Rhode Island. Withdrawals in the Big River Basin can deplete streamflows in the western unnamed tributary to the Carr River, but do not deplete streamflows in the Mishnock River Basin or in the Carr River upstream of Capwell Mill Pond. Because withdrawals deplete streamflows in the study area, the total amount of ground water that may be withdrawn for public supply depends on the minimum allowable streamflow criterion that is applied for each basin.

Water-Resources Investigations Report↗
USGS2016

Optimizing selection of training and auxiliary data for operational land cover classification for the LCMAP initiative

The U.S. Geological Survey’s Land Change Monitoring, Assessment, and Projection (LCMAP) initiative is a new end-to-end capability to continuously track and characterize changes in land cover, use, and condition to better support research and applications relevant to resource management and environmental change. Among the LCMAP product suite are annual land cover maps that will be available to the public. This paper describes an approach to optimize the selection of training and auxiliary data for deriving the thematic land cover maps based on all available clear observations from Landsats 4–8. Training data were selected from map products of the U.S. Geological Survey’s Land Cover Trends project. The Random Forest classifier was applied for different classification scenarios based on the Continuous Change Detection and Classification (CCDC) algorithm. We found that extracting training data proportionally to the occurrence of land cover classes was superior to an equal distribution of training data per class, and suggest using a total of 20,000 training pixels to classify an area about the size of a Landsat scene. The problem of unbalanced training data was alleviated by extracting a minimum of 600 training pixels and a maximum of 8000 training pixels per class. We additionally explored removing outliers contained within the training data based on their spectral and spatial criteria, but observed no significant improvement in classification results. We also tested the importance of different types of auxiliary data that were available for the conterminous United States, including: (a) five variables used by the National Land Cover Database, (b) three variables from the cloud screening ‘‘Function of mask” (Fmask) statistics, and (c) two variables from the change detection results of CCDC. We found that auxiliary variables such as a Digital Elevation Model and its derivatives (aspect, position index, and slope), potential wetland index, water probability, snow probability, and cloud probability improved the accuracy of land cover classification. Compared to the original strategy of the CCDC algorithm (500 pixels per class), the use of the optimal strategy improved the classification accuracies substantially (15-percentage point increase in overall accuracy and 4-percentage point increase in minimum accuracy).

ISPRS Journal of Photogrammetry and Remote Sensing↗
USGS1998

North American landscape characterization project: The production of a continental scale three-decade Landsat data set

The North American Landscape Characterization (NALC) project is a component of the National Aeronautics and Space Administration (NASA) Landsat Pathfinder program. Pathfinder projects are focused on the investigation of global change utilizing current remote sensing technologies. The NALC project is a cooperative effort between the U. S. Environmental Protection Agency (EPA), the U.S. Geological Survey (USGS), and NASA to make Landsat data available to the widest possible user community for scientific research and general public interest. The NALC project is principally funded by the EPA Office of Research and Development and the USGS's Earth Resources Observation Systems (EROS) Data Center (EDC). The objectives of the NALC project are to produce standardized remote sensing data sets, develop standardized analysis methods, and derive standardized land cover change products for a large portion of the North American continent (the conterminous United States and Mexico) (Lunetta and Sturdevant, 1993). The standard product is the NALC “triplicate”;, consisting of co‐registered Landsat multispectral scanner data for the years 1973, 1986, and 1991 (plus or minus one year), plus co‐registered 3 arcsecond digital terrain elevation data. Processing began with the 1986 scene, which was precision corrected (with full terrain correction) to a 60 meter Universal Transverse Mercator base. Automated cross‐correlation procedures were used to co‐register the 1970's and 1990's data to the 1980's base, and independent verifications of registration quality were performed on all triplicate components. The pertinent metadata were compiled in a relational database, which includes WRS2 path/rows, scene ID's, image dates, solar azimuth and elevation, verification RMSE's, and the number of verification control points. NALC triplicate data sets are being used for a number of applications, including the analysis of urbanization patterns, dynamics of climatic fluctuations, deforestation studies, and vegetation classification and mapping. These data are being distributed through the Earth Observing System Data and Information System (EOSDIS) Information Management System (IMS) at a cost of $15(U.S.) for each triplicate.

Geocarto International↗
USGS1973

Floods in New York, 1971

This report, for the calendar year 1971, was prepared at the request of the New York State Department of Transportation under provisions of an agreement between the New York State Department of Environmental Conservation and the U.S. Geological Survey fore a cooperative statewide program investigate the water resources of the State. The report was complied in the New York, Water Resources Division, U.S. Geological Survey, under the direction of Robert J. Dingman, District Chief. The information was obtained from newspaper clippings, publications of the National Weather Service, and the Environmental Data Service, and the Environmental Data Service of the National Oceanic and Atmospheric Administration ("Climatological Data" and "Storm Data"), and records of the U.S. Geological Survey.

New York↗
USGS2009

Ground-Water Quality Data in the Coachella Valley Study Unit, 2007: Results from the California GAMA Program

Ground-water quality in the approximately 820 square-mile Coachella Valley Study Unit (COA) was investigated during February and March 2007 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project was developed in response to the Groundwater Quality Monitoring Act of 2001, and is being conducted by the U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The study was designed to provide a spatially unbiased assessment of raw ground water used for public-water supplies within the Coachella Valley, and to facilitate statistically consistent comparisons of ground-water quality throughout California. Samples were collected from 35 wells in Riverside County. Nineteen of the wells were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study unit (grid wells). Sixteen additional wells were sampled to evaluate changes in water chemistry along selected ground-water flow paths, examine land use effects on ground-water quality, and to collect water-quality data in areas where little exists. These wells were referred to as 'understanding wells'. The ground-water samples were analyzed for a large number of organic constituents (volatile organic compounds [VOC], pesticides and pesticide degradates, pharmaceutical compounds, and potential wastewater-indicator compounds), constituents of special interest (perchlorate and 1,2,3-trichloropropane [1,2,3-TCP]), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (uranium, tritium, carbon-14, and stable isotopes of hydrogen, oxygen, and boron), and dissolved noble gases (the last in collaboration with Lawrence Livermore National Laboratory) also were measured to help identify the source and age of the sampled ground water. A quality-control sample (blank, replicate, or matrix spike) was collected at approximately one quarter of the wells, and the results for these samples were used to evaluate the quality of the data for the ground-water samples. Assessment of the quality-control information resulted in V-coding less than 0.1 percent of the data collected. This study did not attempt to evaluate the quality of water delivered to consumers; after withdrawal from the ground, water typically is treated, disinfected, and (or) blended with other waters to maintain acceptable water quality. Regulatory thresholds apply to treated water that is supplied to the consumer, not to raw ground water. However, to provide some context for the results, concentrations of constituents measured in the raw ground water were compared with health-based thresholds established by the U.S. Environmental Protection Agency (USEPA) and the California Department of Public Health (CDPH) and thresholds established for aesthetic purposes (secondary maximum contaminant levels, SMCL-CA) by CDPH. Most constituents detected in ground-water samples were at concentrations below drinking-water thresholds. Volatile organic compounds, pesticides, and pesticide degradates were detected in less than one-third of the grid well samples collected. All VOC and pesticide concentrations measured were below health-based thresholds. Potential waste-water indicators were detected in less than half of the wells sampled, and no detections were above health-based thresholds. Perchlorate was detected in seven grid wells; concentrations from two wells were above the CDPH maximum contaminant level (MCL-CA). Most detections of trace elements in samples collected from COA Study Unit wells were below water-quality thresholds. Exceptions include five samples of arsenic that were above the USEPA maximum contaminant level (MCL-US), two detections of boron above the CDPH notification level (NL-CA), and two detections of mol

Data Series↗
USGS2014

Petroleum systems and assessment of undiscovered oil and gas in the Anadarko Basin Province, Colorado, Kansas, Oklahoma, and Texas: USGS Province 58

This publication provides research results and related data in support of the U.S. Geological Survey assessment of the undiscovered oil and gas resource potential of the Anadarko Basin Province of western Oklahoma and Kansas, northern Texas, and southeastern Colorado. This province area includes the Las Animas arch of southeastern Colorado, part of the Palo Duro Basin of Texas, and the Anadarko Basin. Results of the geologic analysis and resource assessment are based on the geologic elements of each defined total petroleum system, including hydrocarbon source rocks (source-rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphic and petrophysical properties), hydrocarbon traps (trapping mechanisms and timing), and seals. Using this geologic framework, the U.S. Geological Survey defined 2 total petroleum systems, the Woodford Composite total petroleum system and Pennsylvanian Composite total petroleum system and 12 included assessment units, and quantitatively estimated the undiscovered oil and gas resources within these conventional and continuous (unconventional) AUs. The 13 chapters included in U.S. Geological Survey Digital Data Series DDS–69–EE cover topics that range from the oil and gas resource assessment results (chapter 1 and 5–7), to geological, geochemical, and geophysical research across the province (chapters 3–11), tabular data and graphs in support of the assessment (chapter 12), and data releases of zmap-format grid files that were used to build petroleum system models and a standalone three-dimensional geologic model (chapter 13).

Colorado, Kansas, Oklahoma, Texas↗
USGS2004

Fort Collins Science Center

The U.S. Geological Survey's Fort Collins Science Center (FORT) is one of 17 USGS biological science centers nationwide. FORT conducts research and develops technical applications to assist land managers in understanding and managing biological resources, habitats, and ecosystems. Although the majority of FORT's activities are conducted within the 15-state Central Region of the USGS, many FORT projects are national or international in scope. FORT serves all Department of the Interior land management bureaus and other natural resource agencies. In addition, FORT scientists partner with DOI and other federal entities such as CDC, DOE, EPA, NASA, NIH, and USDA to share expertise and resources. FORT also partners with several universities and works cooperatively with states and nongovernmental organizations. Products and services include reports and publications, predictive models and software, maps and GIS products, and other technical assistance in the form of meetings, workshops, training, field visits, and needs assessments.

Fact Sheet↗
USGS2006

Garnet--An Essential Industrial Mineral and January's Birthstone

Garnet is one of the most common minerals in the world. Occurring in almost any color, it is most widely known for its beauty as a gem stone. Because of its hardness and other properties, garnet is also an essential industrial mineral used in abrasive products, non-slip surfaces, and filtration. To help manage our Nation's resources of such essential minerals, the U.S. Geological Survey (USGS) provides crucial data and scientific information to industry, policymakers, and the public.

Fact Sheet↗
USGS2020

Ohio and Landsat

In Ohio, remote-sensing systems such as Landsat play an important role in monitoring natural resources and informing management decisions on everything from dangerous freshwater algal blooms to gypsy moth defoliation and more. Landsat imagery underpins public and private sector decisions in Ohio and across the Nation for effective adaptation to changing landscapes. Those decisions lead to enhanced agricultural productivity, smart urban development, sustainable forest management, and inland lake water-quality monitoring.

Ohio↗
USGS2006

USGS Abandoned Mine Lands Research Presented at the NAAMLP Meeting in Billings, Mont., Sept. 25, 2006

The following talk was an invited presentation given at the National Association of Abandoned Mine Lands Programs meeting in Billings, Montana on Sept. 25, 2006. The objective of the talk was to outline the scope of the U.S. Geological Survey research, past, present and future, in the area of abandoned mine research. Two large Professional Papers have come out of our AML studies: Nimick, D.A., Church, S.E., and Finger, S.E., eds., 2004, Integrated investigations of environmental effects of historical mining in the Basin and Boulder mining districts, Boulder River watershed, Jefferson County, Montana: U.S. Geological Survey Professional Paper 1652, 524 p., 2 plates, 1 DVD, URL: http://pubs.er.usgs.gov/usgspubs/pp/pp1652 Church, S.E., von Guerard, Paul, and Finger, S.E., eds., 2006, Integrated Investigations of Environmental Effects of Historical Mining in the Animas River Watershed, San Juan County, Colorado: U.S. Geological Survey Professional Paper 1651, 1,096 p., 6 plates, 1 DVD (in press). Additional publications and links can be found on the USGS AML website at URL: http://amli.usgs.gov/ or are accessible from the USGS Mineral Resource Program website at URL: http://minerals.usgs.gov/.

Open-File Report↗
USGS2011

Quality assurance and quality control of geochemical data—A primer for the research scientist

Geochemistry is a constantly expanding science. More and more, scientists are employing geochemical tools to help answer questions about the Earth and earth system processes. Scientists may assume that the responsibility of examining and assessing the quality of the geochemical data they generate is not theirs but rather that of the analytical laboratories to which their samples have been submitted. This assumption may be partially based on knowledge about internal and external quality assurance and quality control (QA/QC) programs in which analytical laboratories typically participate. Or there may be a perceived lack of time or resources to adequately examine data quality. Regardless of the reason, the lack of QA/QC protocols can lead to the generation and publication of erroneous data. Because the interpretations drawn from the data are primary products to U.S. Geological Survey (USGS) stakeholders, the consequences of publishing erroneous results can be significant. The principal investigator of a scientific study ultimately is responsible for the quality and interpretation of the project's findings, and thus must also play a role in the understanding, implementation, and presentation of QA/QC information about the data. Although occasionally ignored, QA/QC protocols apply not only to procedures in the laboratory but also in the initial planning of a research study and throughout the life of the project. Many of the tenets of developing a sound QA/QC program or protocols also parallel the core concepts of developing a good study: What is the main objective of the study? Will the methods selected provide data of enough resolution to answer the hypothesis? How should samples be collected? Are there known or unknown artifacts or contamination sources in the sampling and analysis methods? Assessing data quality requires communication between the scientists responsible for designing the study and those collecting samples, analyzing samples, treating data, and interpreting results. This primer has been developed to provide basic information and guidance about developing QA/QC protocols for geochemical studies. It is not intended to be a comprehensive guide but rather an introduction to key concepts tied to a list of relevant references for further reading. The guidelines are presented in stepwise order beginning with presampling considerations and continuing through final data interpretation. The goal of this primer is to outline basic QA/QC practices that scientists can use before, during, and after chemical analysis to ensure the validity of the data they collect with the goal of providing defendable results and conclusions.

Open-File Report↗
USGS1981

Status of Regional Gravity Project, Kingdom of Saudi Arabia, as of 1 January, 1979

Regional gravity data have now been obtained for approximately 33 percent of the area of the Arabian Shield, associated harrat areas, and the Red Sea coastal plain. Virtually no surveys have been done on the Phanerozoic platform around the edges of the shield, and although regional gravity coverage is available for the Eastern Province from the Arabian American Oil Company, it is confidential. Approximately 4,500 more gravity stations at 10 km spacing are needed to complete the coverage of the shield, and 5,250 are needed on the Phanerozoic platform to the north and east of the shield. The initial gravity maps compiled from the regional gravity project will be along the "geophysical strip", a band approximately 150 km wide across the shield from Al Qawayiyah to the Farasan Islands. As more data become available, additional maps will be compiled at 1:500,000 scale covering the same areas as the USGS Miscellaneous Investigations Maps 1-700-A to I-220-A. Computer software development and implementation for gravity data reduction, storage, retrieval, and display are 80 percent complete. Development and implementation of software for routine semi-quantitative and quantitative interpretation are 50 percent complete. If the Directorate General of Mineral Resources were to commit full support for the regional gravity project, phase 1 (data acquisition) and phase 2 (data reduction and publication of maps and principal facts) could be completed and phase 3 (interpretation) could be about 50 percent completed by the end of the Third Five Year Development Plan (1985).

Open-File Report↗
USGS1994

Estimated water use, by county, in North Carolina, 1990

Data on water use in North Carolina were compiled for 1990 as part of a cooperative agreement between the U.S. Geological Survey and the Division of Water Resources of the North Carolina Department of Environment, Health, and Natural Resources. Data were compiled from a number of Federal, State, and private sources for the offstream water-use categories of public supply, domestic, commercial, industrial, mining, livestock, irrigation, and thermoelectric-power generation. Data also were collected for instream use from hydroelectric facilities. Total estimated offstream water use in the State for 1990 was about 8,940 million gallons per day. About 95 percent of the water withdrawn was from surface-water sources. Thermoelectric-power generation accounted for about 81 percent of all withdrawals. Data for instream water use for hydroelectric-power generation also were compiled. This instream water use totaled about 66,900 million gallons per day. eAch water-use category is summarized in this report by county and source of water supply.

North Carolina↗
USGS1997

Reports and maps of the Military Geology Unit, 1942-1975

Included here are reports and maps which were prepared in the Military Geology Unit of the U. S. Geological Survey from 1942 through 1975. In addition to the references prepared primarily for military use and listed here, more than 200 reports of more general geologic interest were prepared for publication as Survey bulletins and professional papers and in outside journals. These reports are listed in "Publications of the Geological Survey" and other bibliographies. Military Geology reports generally include basic subjects such as rock types, soils, water resources, landforms and vegetation, as well as interpretive subjects such as suitability of terrain for cross-country movement and for construction of roads and airfields in areas throughout the world. Reports on specific areas range from generalized texts with small scab maps derived from published sources to detailed texts with large-scale maps commonly based on photo-interpretation and, especially for Alaska and western Pacific islands, involving field mapping. Other reports treat topics of interest in military geology without reference to specific areas. A number of reports covering the moon include the first photogeologic map of the near side. Authors are cited for some kinds of reports; however, many intelligence reports were published anonymously. Most of the reports were prepared by teams made up mainly of geologists but commonly including soils scientists, botanists, climatologists and geographers. Nearly all the soil scientists and climatologists were members of the World Soil Geography Unit, Soil Survey, Soil Conservation Service, U. S. Department of Agriculture. Manuscripts from this Unit were passed through a common review and other processing, as were the manuscripts originating in the Military Geology office, to be issued under the aegis of the latter. In some instances where it has not been possible to list all authors, names of project supervisors are given. File copies of many of the Military Geology reports prepared since 1975 are kept in the Special Geologic Studies Group, U.S. Geological Survey, National Center, Reston, and may be examined there by appropriately cleared persons. Additionally, copies of many of the unclassified studies are in the U.S. Geological Survey Library. Some of the older reports are in the files of the Terrain Analysis Center, Fort Belvoir, Virginia, and other offices within the Corps of Engineers. Most of the reports are out of print and many of the other studies are no longer available.

Open-File Report↗
USGS1997

Estimated water use, by county, in North Carolina, 1995

Data on water use in North Carolina were compiled for 1995 as part of a cooperative agreement between the U.S. Geological Survey and the Division of Water Resources of the North Carolina Department of Environment and Natural Resources. Data were compiled from a number of Federal, State, and private sources for the offstream water-use categories of public supply, domestic, commercial, industrial, mining, livestock, irrigation, and thermoelectric-power generation. Data also were collected for instream use from hydroelectric facilities. Total withdrawals (fresh and saline) during 1995 were an estimated 9,286 million gallons per day for the offstream water-use categories. About 94 percent of the water withdrawn was from surface water. Thermoelectric-power generation accounted for 80 percent of all withdrawals. Instream water use for hydroelectric-power generation totaled about 56,400 million gallons per day. Each water-use category is summarized in this report by county and source of water supply.

North Carolina↗
USGS1998

Water use trends and demand projections in the Northwest Florida Water Management District

The Northwest Florida Water Management District is located in the western panhandle of Florida and encompasses about 11,200 square miles. In 1995, the District had an estimated population of 1.13 million, an increase of about 47 percent from the 1975 population of 0.77 million. Over 50 percent of the resident population lives within 10 miles of the coast. In addition, hundreds of thousands of visitors come to the coastal areas of the panhandle during the summer months for recreation or vacation purposes. Water withdrawn to meet demands for public supply, domestic self-supplied, commercial-industrial, agricultural irrigation, and recreational irrigation purposes in the District increased 18 percent (52 million gallons per day) between 1970 and 1995. The greatest increases were for public supply and domestic self-supplied (99 percent increase) and for agricultural irrigation (60 percent increase) between 1970 and 1995. In 1995, approximately 70 percent of the water withdrawn was from ground-water sources, with the majority of this from the Floridan aquifer system. The increasing water demands have affected water levels in the Floridan aquifer system, especially along the coastal areas. The Northwest Florida Water Management District is mandated under the Florida Statutes (Chapter 373) to protect and manage the water resources in this area of the State. The mandate requires that current and future water demands be met, while water resources and water-dependent natural systems are sustained. For this project, curve fitting and extrapolation were used to project most of the variables (population, population served by public supply, and water use) to the years 2000, 2005, 2010, 2015, and 2020. This mathematical method involves fitting a curve to historical population or water-use data and then extending this curve to arrive at future values. The population within the region is projected to reach 1,596,888 by the year 2020, an increase of 41 percent between 1995 and 2020. Most of the population in this region will continue to reside in the urban areas of Pensacola and Tallahassee, and along the coastal areas. The population served by public water supply is projected to reach 1,353,836 by the year 2020, an increase of nearly 46 percent between 1995 and 2020. Total water demand for the Northwest Florida Water Management District is projected to reach 940.2 million gallons per day in 2000, 1,003.1 million gallons per day in 2010, and 1,059.1 million gallons per day in 2020. Excluding water withdrawn for power generation from these totals, water demands will increase 34 percent between 1995 and 2020, and 58 percent between 1970 and 2020. Specifically, public supply demands are projected to increase 74.1 million gallons per day (53 percent) and domestic self-supplied and small public supply systems demands are projected to increase 9.1 million gallons per day (28 percent) between 1995 and 2020. Commercial- industrial self-supplied demands are projected to increase about 16.9 million gallons per day (13 percent) between 1995 and 2020. Agricultural and recreational irrigation demands combined are projected to increase 16.8 million gallons per day (48 percent) between 1995 and 2020. Water demands for power generation are projected to increase about 53.9 million gallons per day (10 percent) between 1995 and 2020. Although power generation water use shows a projected increase during this time, plant capacities are not expected to change dramatically.

Open-File Report↗
USGS2006

The occurrence of volatile organic compounds in aquifers of the United States

The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program recently completed a national assessment of volatile organic compounds (VOCs) in ground water (Zogorski and others, 2006). As part of this assessment, samples of ambient ground water collected from 3,498 wells during 1985-2002 were selected for characterizing the occurrence of 55 VOCs in 98 aquifer studies. The 55 VOCs were assigned to the following groups on the basis of their primary usage (or origin): (1) fumigants, (2) gasoline hydrocarbons, (3) gasoline oxygenates, (4) organic synthesis compounds, (5) refrigerants, (6) solvents, and (7) trihalo-methanes (chlorination by-products). The samples were collected throughout the conterminous United States as well as Alaska and Hawaii. The sampled wells had a variety of uses including domestic supply (61 percent), public supply (15 percent), monitoring (10 percent), other (13 percent), and unknown (1 percent). NAWQA aquifer studies are large-scale resource assessments of ground water that provide a general characterization of water-quality conditions in locally and regionally important aquifers or portions thereof. In general, the aquifers (or portions thereof) selected for study were some of the most intensively used aquifers for drinking water in greaterHawaiiOahuAlaskathe Nation. The 98 aquifer studies collectively provide an important national perspective on the current (1985-2002) extent of VOC contamination and regional patterns of VOC occurrence in ground water. More information about this national assessment of VOCs is available at a supporting Web site (http://water.usgs.gov/nawqa/vocs/national_assessment).

Scientific Investigations Map↗