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At least 73 records · Page 4Linked to original sources
USGS1979

Investigations by the U.S. Geological Survey of soil and moisture conservation on public domain lands, 1941-1964

The passage of the Taylor Grazing Act in 1934 marked the end of an era in the land policies in the United States in that disposal of the public lands by homesteading was terminated except under rigidly prescribed procedures, and the remaining public lands covering about 175 million acres in the western conterminous states were brought under regulatory authority for grazing use. In 1934 the lands were mostly in a severe state of deterioration as a result of overgrazing and drought. In addition to reducing numbers of livestock using the lands, successive programs of conservation practices were established of which the Soil and Moisture Conservation Program of the Department of the Interior is of particular interest here. The services of the Geological Survey, in an investigational and advisory capacity were enlisted in this program. The work of the Geological Survey has consisted of the collection of hydrologic data, investigations of range-water supplies to facilitate management and provide information for design of structures and land-treatment measures. Appraisal of the effects of treatment practices has also been an important activity. Conservation on the public domain involves mainly growing vegetation for forage and reducing erosion. The two elements are intimately related--accomplishment in one is usually reflected by an improvement in the other. Erosion is a serious problem on most of the public domain, but particularly in the Colorado River and Rio Grande basins where, despite low annual water yields, the public domain and similar lands on the Indian reservations contribute the major part of the sediment measured at the downstream gaging stations. In parts of the Missouri River basin also, erosion is obviously very active but the sediment yield contributed by the public domain cannot be as readily isolated. The reasons for the erosion are generally evident--the erodibility of the rock and soils and the sparsity of vegetation as a result of low precipitation, unfavorable soils, or past land use. How much is due to the land use is still controversial, resulting in many questions relative to planning corrective measures. The problem facing the early administrators of the Taylor Grazing Act to bring about proper use and conservation of the public domain was a difficult one because of the lack of records on actual grazing use in animal-unit months of the qualified allottees and the lack of data on treatment practices in an arid area. Reduction of grazing was imperative in some localities, but generally, it could not be brought about as rapidly as it should have been. Numbers of animal units in the grazing districts were reduced from about 3.6 million in 1941 to about 3.2 million in 1964, whereas the areas included in districts was increased about 3 percent. Reductions are still being made in certain areas where deterioration is evident. One of the earliest activities connected with management of the range was the development of water supplies to facilitate the distribution of grazing. The investigations needed for such development formed a large part of the early work in the Soil and Moisture program of the Geological Survey and has continued to be a major activity to the present time. Most of the work has involved investigations of sites for wells but has included also the investigation of proposed spring developments and collection of hydrologic data for use in reservoir design. Well-site investigations have been of two general types: (1) the investigation of a site selected by the land administration agency, and (2) an areal investigation covering entire grazing districts or units thereof. In each type of investigation, a study is made of the geology and the recharge conditions. Reports are prepared giving estimates of the depth of drilling required, the depth to water, the yield, and the quality of the water, together with other information on drilling conditions and developing. Springs are a significant so

Open-File Report↗
USGS2008

Managing public and media response to a reawakening volcano: lessons from the 2004 eruptive activity of Mount St. Helens

Volcanic eruptions and other infrequent, large-scale natural disturbances pose challenges and opportunities for public-land managers. In the days and weeks preceding an eruption, there can be considerable uncertainty surrounding the magnitude and areal extent of eruptive effects. At the same time, public and media interest in viewing developing events is high and concern for public safety on the part of local land managers and public safety officials is elevated. Land managers and collaborating Federal, State, and local officials must decide whether evacuations or restrictions to public access are necessary, the appropriate level of advance preparation, and how best to coordinate between overlapping jurisdictions. In the absence of a formal Federal or State emergency declaration, there is generally no identified source of supplemental funding for emergency-response preparation or managing extraordinary public and media response to developing events. In this chapter, we examine responses to escalating events that preceded the 2004 Mount St. Helens eruption and changes in public perception during the extended period of the largely nonexplosive, dome-building eruption that followed. Lessons learned include the importance of maintaining up-to-date emergency-response plans, cultivating close working relationships with collaborating agencies, and utilizing an organized response framework that incorporates clearly defined roles and responsibilities and effective communication strategies.

Washington↗
USGS2012

Hydrogeology, water chemistry, and transport processes in the zone of contribution of a public-supply well in Albuquerque, New Mexico, 2007-9

The National Water-Quality Assessment Program (NAWQA) of the U.S. Geological Survey began a series of groundwater studies in 2001 in representative aquifers across the Nation in order to increase understanding of the factors that affect transport of anthropogenic and natural contaminants (TANC) to public-supply wells. One of 10 regional-scale TANC studies was conducted in the Middle Rio Grande Basin (MRGB) in New Mexico, where a more detailed local-scale study subsequently investigated the hydrogeology, water chemistry, and factors affecting the transport of contaminants in the zone of contribution of one 363-meter (m) deep public-supply well in Albuquerque. During 2007 through 2009, samples were collected for the local-scale study from 22 monitoring wells and 3 public-supply (supply) wells for analysis of major and trace elements, arsenic speciation, nutrients, dissolved organic carbon, volatile organic compounds (VOCs), dissolved gases, stable isotopes, and tracers of young and old water. To study groundwater chemistry and ages at various depths within the aquifer, the monitoring wells were divided into three categories: (1) each shallow well was screened across the water table or had a screen midpoint within 18.3 m of the water level in the well; (2) each intermediate well had a screen midpoint between about 27.1 and 79.6 m below the water level in the well; and (3) each deep well had a screen midpoint about 185 m or more below the water level in the well. The 24-square-kilometer study area surrounding the "studied supply well" (SSW), one of the three supply wells, consists of primarily urban land within the MRGB, a deep alluvial basin with an aquifer composed of unconsolidated to moderately consolidated deposits of sand, gravel, silt, and clay. Conditions generally are unconfined, but are semiconfined at depth. Groundwater withdrawals for public supply have substantially changed the primary direction of flow from northeast to southwest under predevelopment conditions, to west to east under modern conditions. Analysis of age tracers indicates that groundwater from most sampled wells is dominated by old (pre-1950) water, ranging in mean age from about 4,000 years to more than 22,000 years, but includes a fraction of young (post-1950) recharge. Patterns in chemical and isotopic data are consistent with the conclusions that shallow groundwater in the area typically includes a fraction that evaporated prior to recharge and (or) flushed accumulated solutes out of the unsaturated zone during recharge, and that shallow groundwater has mixed to deeper parts of the aquifer, which receives recharge mainly by seepage from the Rio Grande. Among shallow and intermediate wells that produced water with a fraction of young recharge, that fraction ranged between 1.5 and 46 percent. Samples from the two deep wells had groundwater ages exceeding 18,000 years, with no fraction of young recharge. Two supply wells (including the SSW) had a fraction of young recharge, which ranged between about 3 and 11 percent, despite mean groundwater ages exceeding 10,000 years. The fraction of young recharge to the SSW varied seasonally, probably because seasonal pumping patterns affected local hydraulic gradients and (or) because of flow through the well bore when the SSW is not pumping. Well-bore flow data collected during winter (low-pumping season) indicated that about 61 percent of the water pumped from the SSW entered the well from the intermediate part of the aquifer, and that the remaining 39 percent entered from the deep part of the aquifer. Volatile organic compounds (VOCs) were detected in samples from most shallow and intermediate monitoring wells and from two of three supply wells, including the SSW. Detected VOCs were primarily chlorinated solvents or their degradation products. Many of the wells in which most of these VOCs were detected are located near known sites of solvent contamination that were targeted for sampling because trichloroethylene (TCE) and cis-1,2-dichloroethylene had been detected in the SSW, and several of these wells may have become contaminated at least partly because of enhanced vertical migration associated with the pumping of and (or) direct migration down deep well bores. Except for TCE in the sample from a shallow monitoring well, all detections of VOCs were at concentrations below Maximum Contaminant Levels (MCLs) set by the U.S. Environmental Protection Agency. Concentrations of all VOCs detected in the supply wells were less than one-tenth of the corresponding MCLs. However, the presence of VOCs in all but deep groundwater, including the detection of chloroform (a chlorination byproduct) in several shallow wells, indicates that groundwater in the study area commonly is affected by human activities, even to substantial depths. The only natural contaminant detected at concentrations near or above its MCL was arsenic, which has been detected at elevated concentrations across broad areas of the MRGB. Concentrations of arsenic, present primarily as arsenate, exceeded the MCL of 10 micrograms per liter (μg/L) in water from the two deep wells (one of which had the highest concentration, 35 μg/L), from one intermediate well, and from two supply wells, including the SSW. Water-quality and solid-phase data from this study are consistent with elevated arsenic concentrations in groundwater being related to pH-dependent desorption of arsenic from ferric oxyhydroxides in sediments in deep parts of the aquifer. Concentrations of nitrate ranged between 1.3 and 5.4 milligrams per liter (mg/L) in water from shallow wells screened across the water table, but were less than 0.9 mg/L in water from all but one deeper well. Nitrogen isotopes and chloride/bromide ratios for shallow wells were consistent with natural soil nitrogen. Nitrate concentrations and nitrogen isotopes indicated that denitrification is occurring at intermediate aquifer depths, and that the progress of the denitrification reaction typically is greatest for wells that include a fraction of groundwater associated with particular recharge sources or with known sites of contamination contributing organic compounds that can provide a carbon source for microbial respiration. Overall, hydrologic and chemical data from the study area indicate that young recharge is reaching the aquifer across broad areas and is migrating from shallow to intermediate depths of the aquifer as a result of mixing that is associated with human development of groundwater. Consequently, groundwater that human activities in the urban study area have affected is present at depths that are within the screened intervals of public-supply wells, resulting in detections of VOCs and implying greater vulnerability to anthropogenic contamination than might be assumed based on the dominantly old age of the regional groundwater. However, the fractions of old groundwater that public-supply wells produce substantially dilute the anthropogenic contaminants, while contributing natural contaminants (primarily arsenic) to the wells. Based on data from the SSW, vulnerability of public-supply wells to natural and anthropogenic contaminants in the area changes through time, including with seasonal changes in pumping stresses that alter the fractions of young and old water being contributed to wells.

New Mexico↗
USGS2018

Public-supply water use and self-supplied industrial water use in Tennessee, 2010

The U.S. Geological Survey (USGS), in cooperation with the Tennessee Department of Environment and Conservation, Division of Water Resources, prepared this report and displayed and analyzed water use by self-supplied industrial and public-supply water systems in Tennessee for 2010. Public-supply water systems in Tennessee provide water for domestic, industrial, and commercial uses and for municipal services. In 2010, 474 public-supply water systems distributed 917 million gallons per day (Mgal/d) of surface water (67 percent, 617 Mgal/d) and groundwater (33 percent, 300 Mgal/d) to a population of 5.7 million in Tennessee. Gross per capita water use in Tennessee during 2010 was 162 gallons per day. Since 1950, water withdrawals by public-supply water systems in Tennessee have increased from 160 Mgal/d to 917 Mgal/d in 2010. Each of the 95 counties in Tennessee was served by at least 1 public-supply water system in 2010. Tennessee public-supply water systems withdraw less groundwater than surface water, and surface-water use has increased at a faster rate than groundwater use. Since 2005, surface-water withdrawals have increased by 26 Mgal/d, and groundwater withdrawals have decreased by 29 Mgal/d, which is the first decrease in groundwater withdrawals since 1950; however, 29 systems reported increased groundwater withdrawals during 2010, and 12 of these 29 systems reported increases of 1 Mgal/d or more. Davidson County had the largest surface-water withdrawal rate (136 Mgal/d) in 2010. The largest groundwater withdrawal rate (151 Mgal/d) by a single public-supply water system was reported by Memphis Light, Gas and Water, which served more than 669,000 people in Shelby County in 2010. Self-supplied industrial water use includes water for such purposes as fabrication, processing, washing, diluting, cooling, or transporting a product; incorporating water into a product; or for sanitation needs in facilities that manufacture various products. Water withdrawals for self-supplied industrial water use during 2010 were about 776 Mgal/d. This quantity represented a decrease of 7 Mgal/d since 2005. In Tennessee, self-supplied industrial water withdrawals were primarily for chemical and allied products (555 Mgal/d), paper and allied products (107 Mgal/d), aeronautical products (71.5 Mgal/d), concrete and glass products (9.74 Mgal/d), and primary metal products (4.49 Mgal/d); and these products accounted for 96 percent (747 Mgal/d) of the self-supplied industrial water withdrawals in 2010. Surface water supplied 94 percent of the water (728 Mgal/d) for self-supplied industrial purposes, and groundwater supplied 6 percent (47.6 Mgal/d). Self-supplied industrial water withdrawals in Sullivan County were 488 Mgal/d and accounted for 61 percent of the self-supplied industrial water withdrawals. The largest groundwater withdrawal, 14.9 Mgal/d, by a single self-supplied industry was in Memphis, Tennessee, for the production of chemicals and allied products.

Tennessee↗
USGS2019

Estimated use of water in the Cumberland River watershed in 2010 and projections of public-supply water use to 2040

The U.S. Army Corps of Engineers (USACE), Nashville District, is conducting ongoing water-supply analyses of USACE reservoirs in the Cumberland River watershed to identify areas where potential water-resources issues may arise in the future. To assist the USACE in their efforts, the U.S. Geological Survey, in cooperation with the USACE, collected and analyzed water-use data to estimate public-supply, self-supplied industrial, irrigation, and thermoelectric water use for 2010 and to project water demand to 2040 for the Cumberland River watershed area. Estimates of water use for public supply were projected in 10-year increments through 2040 and were based on 2010 public water-supply data and population projections for 2020 to 2040. Additionally, estimates of consumptive use, wastewater releases, and thermoelectric power and industrial return flows were calculated. All estimates are presented for the entire watershed and for the 10 reservoir catchment areas (RCAs) within the watershed. Estimated water withdrawals in the Cumberland River watershed during 2010 averaged 3,456.23 million gallons per day (Mgal/d) of freshwater for offstream use. Return flow was estimated to be 3,370.08 Mgal/d, or 98 percent of the water withdrawn during 2010. Total consumptive use accounts for the remaining 2 percent, or 86.2 Mgal/d. Estimates of water withdrawals by source indicate that withdrawals from surface water during 2010 accounted for more than 99 percent of the total withdrawals, or 3,437.90 Mgal/d. Total groundwater withdrawals during 2010 were 18.33 Mgal/d, or less than 1 percent of the total withdrawals. During 2010, withdrawals by category were estimated as follows: thermoelectric power, 3,051.12 Mgal/d; public supply, 360.00 Mgal/d; industrial, 31.5 Mgal/d; and irrigation, 13.6 Mgal/d. Return flows were estimated as thermoelectric power, 3,051.06 Mgal/d, and industrial and public supply, 319.02 Mgal/d. Consumptive use was estimated as thermoelectric power, 0.06 Mgal/d; industrial and public supply, 72.5 Mgal/d; and irrigation, 13.6 Mgal/d. By 2040, the public supply of raw and (or) finished water to meet demand for the 10 RCAs is projected to increase 48 percent to 532.51 Mgal/d. This projected increase includes an increase from 51.5 to 72.5 Mgal/d, or 41 percent, in the Barkley RCA. The combined total water demand for the Cheatham, J. Percy Priest, and Old Hickory RCAs is projected to increase from 224.08 to 359.58 Mgal/d, or 61 percent. The combined total water demand for the Center Hill, Cordell Hull, and Dale Hollow RCAs is projected to increase from 31.7 to 43.0 Mgal/d, or 36 percent. The combined total water demand for the Martins Fork, Laurel, and Wolf Creek RCAs is projected to increase from 52.8 to 57.4 Mgal/d, or 9 percent. The only RCA in the watershed with a projected decrease in water demand is Martins Fork.

Kentucky, Tennessee, Virginia↗
USGS2004

Quality and sources of ground water used for public supply in Salt Lake Valley, Salt Lake County, Utah, 2001

Ground water supplies about one-third of the water used by the public in Salt Lake Valley, Utah. The occurrence and distribution of natural and anthropogenic compounds in ground water used for public supply in the valley were evaluated. Water samples were collected from 31 public-supply wells in 2001 and analyzed for major ions, trace elements, radon, nutrients, dissolved organic carbon, methylene blue active substances, pesticides, and volatile organic compounds. The samples also were analyzed for the stable isotopes of water (oxygen-18 and deuterium), tritium, chlorofluorocarbons, and dissolved gases to determine recharge sources and ground-water age. Dissolved-solids concentration ranged from 157 to 1,280 milligrams per liter (mg/L) in water from the 31 public-supply wells. Comparison of dissolved-solids concentration of water sampled from the principal aquifer during 1988-92 and 1998-2002 shows a reduction in the area where water with less than 500 mg/L occurs. Nitrate concentration in water sampled from 12 of the 31 public-supply wells was higher than an estimated background level of 2 mg/L, indicating a possible human influence. At least one pesticide or pesticide degradation product was detected at a concentration much lower than drinking-water standards in water from 13 of the 31 wells sampled. Chloroform was the most frequently detected volatile organic compound (17 of 31 samples). Its widespread occurrence in deeper ground water is likely a result of the recharge of chlorinated public-supply water used to irrigate lawns and gardens in residential areas of Salt Lake Valley. Environmental tracers were used to determine the sources of recharge to the principal aquifer used for public supply in the valley. Oxygen-18 values and recharge temperatures computed from dissolved noble gases in the ground water were used to differentiate between mountain and valley recharge. Maximum recharge temperatures in the eastern part of the valley generally are below the range of valley water-table temperatures indicating that mountain-block recharge must constitute a substantial fraction of recharge to the principal aquifer in this area. Together, the recharge temperature and stable-isotope data define two zones with apparently high proportions of valley recharge on the east side of the valley. The possibility of water samples containing a substantial proportion of water recharged before thermonuclear testing began in the early 1950s (pre-bomb) was evaluated by comparing the initial tritium concentration of each sample (measured tritium plus measured tritiogenic helium-3) to that of local precipitation at the apparent time of recharge. Three interpreted-age categories were determined for water from the sampled wells: (1) dominantly pre-bomb; (2) dominantly modern; and (3) modern or a mixture of pre-bomb and modern. Apparent tritium/helium-3 ages range from 3 years to more than 50 years. Water generally becomes older with distance from the mountain front, with the oldest water present in the discharge area. The presence of anthropogenic compounds at concentrations above reporting levels and elevated nitrate concentrations (affected wells) in the principal aquifer is well correlated with the distribution of interpreted-age categories. All of the wells (10 of 10) with dominantly modern water are affected. Seventy percent (7 of 10) of the wells with dominantly modern or a mixture of modern and pre-bomb waters are affected. Only 1 of the 11 wells with dominantly pre-bomb water is affected. Anthropogenic compounds were not detected in water with an apparent age of more than 50 years, except for water from one well. All of the samples that consisted mostly of modern water contained at least one anthropogenic compound.

Utah↗
USGS1994

Identification of potential public water-supply areas of the Cape Cod aquifer, Massachusetts, using a geographic information system

Potential public water-supply areas of the Cape Cod aquifer, Massachusetts, were identified using a geographic information system (GIS) to aid regional and local ground-water resource management efforts. Criteria were selected to identify potential areas on the basis of data restrictions in addition to State requirements for siting new public water- supply wells, Federal or local restrictions on land use, and general hydrogeologic or water-quality concerns. Data layers were created for each criterion and overliad to eliminate areas from consideration as potential public water supplies. Remaining areas, those not included within the applied criteria, are the primary areas to consider for potential public water supplies. The areas identified in this analysis as potential public water supplies range from 0.5 to 7.9 percent of the individual flow cells, or 5.6 percent of the total flow cell area. The criteria were ranked so that criteria more limiting to potential public water supplies were given a higher rank than other criteria. The ranking scheme allows for the inclusion of areas with lower ranked criteria as potential public water supplies. Results can be viewed on a plat in this report, or accessed using the map-based, menu-driven GIS application, which provides interactive display and query of investigation results.

Water-Resources Investigations Report↗
USGS1954

The industrial utility of public water supplies in the United States, 1952, part 1, States east of the Mississippi River

Public water supplies are utilized extensively by industries for processing, cooling, and steam generation. The requirements as to quality of water for each industry are specific, therefore information on the quality or chemical character of the water supply is essential not only in the location of industrial plants but also is an aid in the manufacture and distribution of products. Data are given in this report on the water supplies for 1,315 of the larger cities (or places) throughout the United States. The population of these cities represents 58. 3 percent of the total population (1950 census), and more than 90 percent of the total urban population, of the United States. Part 1 of the report contains data for 819 cities east of the Mississippi River, and part 2 includes data for 416 cities west of the river. All cities of 15,000 or more population and many cities of smaller population are included. The information given for each place includes, in most instances, population of the place; ownership, source, and treatment of supply; storage facilities for both raw and finished water; and chemical analyses of the supplies. The chemical quality of a water affects its industrial utility. A total of 2, 506 chemical analyses of the supplies for the places included are shown. Surface-water supplies, generally, are more variable in composition than ground-water supplies, but contain less mineral matter in solution. Many of the treated public supplies require further treatment to make them satisfactory for some industrial uses. Of the total of 1,315 places included in the report, 711 receive surface-water supplies; 472 receive ground-water supplies, and 132 receive mixed supplies. The population served by these supplies is about 88,000,000, of which about 71,000,000 receive surface-water supplies and 17,000,000 groundwater supplies. Hardness of water supplies with respect to industrial use is given much attention. The hardness of the large public supplies ranges from less than 5 parts per million to about 700 parts. About 52, 000, 000 people are furnished with water having hardness of 100 parts per million or less. The weighted average hardness (average hardness of supplies weighted according to the population served) of finished water of surface supplies is 82 parts per million; of ground supplies, 162 parts; and of all supplies, 97 parts. The weighted average hardness of raw water of surface, ground, and all supplies are 96,200, and 116 parts per million, respectively. The average hardness (based on the average hardness of each supply and the number of supplies) of finished water of surface supplies is 85 parts per million; of ground supplies, 164 parts; and of all supplies, 121 parts. The average hardness of the raw water supplies are 94, 192 and 139 parts per million, respectively. The median hardness of finished water of all supplies is 91 parts per million, and of the raw water supplies, 90 parts. The treatment of a public water supply is planned principally to give a water that is bacterially safe for public use, and to eliminate or minimize certain undesirable characteristics of the water; Of the supplies for the places in this report, a total of 117 (3 surface supplies and 114 ground supplies) receive no treatment; 393 supplies receive no treatment other than chlorination; and the remainder receive treatment in addition to chlorination. The supplies for 171 cities are softened. Rapid sand filter plants are in use for 533 cities, exclusive of those in use at places where the water is softened. Slow sand-filter plants are in use at 35 places. A population of about 40, 000, 000 is served with water from these filter plants. The total number of treatment plants, exclusive of facilities for chlorination, for most of the places in this report is 660. The total capacity of these plants in millions of gallons per day is 10, 694. A total of 693 places report raw-water storage facilities having a total capacity of 2, 460, 346 millions of gallons; a total of 1,081 places report finished-water storage facilities having a total capacity of 24, 557 millions of gallons. Investigations by others have shown that a definite relationship exists between fluoride in drinking water and the incidence of dental caries in the teeth of children. A total of about 85 percent of the population served from the large public supplies receive water having a fluoride concentration in the range of 0.0 to 0. 5 part per million. Few large public supplies contain fluoride in concentrations in excess of 3 parts per million. A total of 155 places of those included in the report received fluoridated water in 1955.

Water Supply Paper↗
USGS2020

Bridging the research-management gap: Landscape ecology in practice on public lands in the western United States

The field of landscape ecology has grown and matured in recent decades, but incorporating landscape science into land management decisions remains challenging. Many lands in the western United States are federally owned and managed for multiple uses, including recreation, conservation, and energy development. We argue for stronger integration of landscape science into the management of these public lands. We open by outlining the relevance of landscape science for public land planning, management, and environmental effects analysis, including pertinent laws and policies. We identify challenges to integrating landscape science into public land management, including the multijurisdictional nature and complicated spatial pattern of public lands, the capacity of agencies to identify and fill landscape science needs, and public perceptions about the meaning of landscape approaches to management. We provide several recent examples related to landscape monitoring, restoration, reclamation, and conservation in which landscape science products were developed specifically to support decision-making. We close by highlighting three actions - elevating the importance of science-management partnerships dedicated to coproducing actionable landscape science products, identifying where landscape science could foster efficiencies in the land-use planning process, and developing scenario-based landscape models for shrublands - that could improve landscape science support for public land planners and managers.

Arizona, California, Colorado, Idaho, Montana, New↗
USGS2022

Populations using public-supply groundwater in the conterminous U.S. 2010; Identifying the wells, hydrogeologic regions, and hydrogeologic mapping units

Most Americans receive their drinking water from publicly supplied sources, a large portion of it from groundwater. Mapping these populations consistently and at a high resolution is important for understanding where the resource is used and needs to be protected. The results show that 269 million people are supplied by public supply, 107 million are supplied by groundwater and 162 million are supplied by surface water. The population using public supply drinking water was mapped in two ways: the census enhanced method (CEM) evenly distributes the population across populated census blocks, and the urban land-use enhanced method (ULUEM) distributes the population only to certain urban land use designations. In addition, a two-dimensional polygon dataset was created for the conterminous U.S. that identifies 177 unique Hydrogeologic Mapping Units (HMUs) with similar hydrogeologic characteristics. The HMUs do not overlap, but they can delineate areas where stacked hydrogeologic regions (HRs) contribute drinking water from below the surface. HRs are waterbearing geologic regions identified as either a principal aquifers (PA) or secondary hydrogeologic regions (SHR). Within each HMU, the wells were used to determine the proportion of each HR that is providing groundwater to the HMU. In 63% of the HMUs, a single HR is providing water to the public supply wells located within it, while the rest of the HMUs show that the wells are tapping up to a maximum of four stacked HRs. In total, groundwater from 108 HRs provide drinking water for public supply, six of which provide more than 50% of the groundwater used for public supply drinking water. The aquifer serving the largest number of equivalent people (>17 million) is the glacial aquifer. The HR providing the greatest number of people per km 2 is the Biscayne aquifer in Florida at nearly 453 people per km 2 .

Science of the Total Environment↗
USGS2018

Reconnaissance of mixed organic and inorganic chemicals in private and public supply tapwaters at selected residential and workplace sites in the United States

Safe drinking water at the point-of-use (tapwater, TW) is a United States public health priority. Multiple lines of evidence were used to evaluate potential human health concerns of 482 organics and 19 inorganics in TW from 13 (7 public supply, 6 private well self-supply) home and 12 (public supply) workplace locations in 11 states. Only uranium (61.9 μg L –1 , private well) exceeded a National Primary Drinking Water Regulation maximum contaminant level (MCL: 30 μg L –1 ). Lead was detected in 23 samples (MCL goal: zero). Seventy-five organics were detected at least once, with median detections of 5 and 17 compounds in self-supply and public supply samples, respectively (corresponding maxima: 12 and 29). Disinfection byproducts predominated in public supply samples, comprising 21% of all detected and 6 of the 10 most frequently detected. Chemicals designed to be bioactive (26 pesticides, 10 pharmaceuticals) comprised 48% of detected organics. Site-specific cumulative exposure–activity ratios (∑ EAR ) were calculated for the 36 detected organics with ToxCast data. Because these detections are fractional indicators of a largely uncharacterized contaminant space, ∑ EAR in excess of 0.001 and 0.01 in 74 and 26% of public supply samples, respectively, provide an argument for prioritized assessment of cumulative effects to vulnerable populations from trace-level TW exposures.

Environmental Science & Technology↗
USGS2026

Resources to inform the 2026 Colorado Climate Preparedness Roadmap: Compound hazards and associated public health implications

Changing environmental conditions are increasing the frequency and severity of extreme weather and environmental hazards, including heat waves, wildfires, drought, reduced water quality, and degraded air quality from ozone (O3) and fine particulate matter pollution (AghaKouchak et al., 2020; Bolinger et al., 2024; Colorado Health Institute, 2023a; Fann et al., 2015; IPCC, 2023a; Nagamoto et al., 2024; Nolte et al., 2018, 2021; Zscheischler et al., 2020). Strong scientific evidence indicates that climate change will increase risks to public health and safety throughout the 21st century, particularly through compound climate events (AghaKouchak et al., 2020; Cascio, 2018; Childs et al., 2022; Ebi, 2025; IPCC, 2023a, 2023b; Ma et al., 2024; Marlier et al., 2026; National Academy of Medicine, 2025; Reid et al., 2016; Reid & Maestas, 2019; Simpson et al., 2023; van den Hurk et al., 2023; Volckens, 2024; Zscheischler et al., 2018, 2020). Compound hazards, which are co-occurring or sequential hazards such as heat waves occurring alongside drought, wildfire, and poor air quality from smoke, can amplify public health risks beyond the effects of individual hazards alone (Marlier et al., 2026; Zscheischler et al., 2020). In Colorado, compound climate events with clear implications for public health are already evident (see “Core definitions” section for additional context on compound climate events). Recent statewide assessments have documented increasing heat waves, drought, and wildfires linked to rising temperatures, while emerging data show that climate change is reversing decades of air quality improvements through increased O3 and fine particulate matter pollution due to wildfire, and increased aerosolized topsoil (i.e., dust) due to drought (Bolinger et al., 2024; Childs et al., 2022; Fann et al., 2015; Ghanbari et al., 2023; Larsen et al., 2022; Nolte et al., 2018, 2021; Volckens, 2024). These environmental shifts are associated with increases in eye and kidney-health related concerns, heat-related illness, exacerbations of asthma and other respiratory conditions, increased risk of infectious disease, cardiovascular stress, and mental health impacts, with disparities in risk for children, older adults, outdoor workers, and communities with existing health and economic vulnerabilities (Baraghoshi et al., 2023; Butler-Dawson et al., 2026; Cascio, 2018; Cleland et al., 2022; Colorado Health Institute, 2023a; Grover et al., 2024; Lee et al., 2023; Ma et al., 2024; Macaluso et al., 2024; Marlier et al., 2026; National Academy of Medicine, 2025; Patnaik et al., 2024; Peters et al., 2019; Reid et al., 2016; Reid & Maestas, 2019). The state is actively pursuing strategies to mitigate the risks of these compound climate events on the public, including expanding climate and health surveillance, strengthening early-warning systems and public communication around smoke and air quality, and developing integrated policy agendas that link climate mitigation, adaptation, and health equity (CDPHE, 2025; Colorado Health Institute, 2023b; Zemaitis & Bailey, 2024). For example, state and partner organizations have articulated cross-sector goals to prepare for health impacts related to extreme heat, wildfires, flooding, drought, declines in water quality, and poor air quality, including updating workplace safety protocols, enhancing community-based resilience, adapting clinical care assessments to include climate-related stressors, and improving access to mental and behavioral health services following climate-related disasters (Colorado Health Institute, 2023b; CDPHE, 2025; Zemaitis & Bailey, 2024). To better prepare for current risks and make informed decisions, more information is needed, including methods to analyze historical and projected conditions in near real time, characterize interactions among compound hazards, and translate climate and air quality science into actionable guidance for public health agencies, health care systems, and communities across Colorado (Ebi, 2025; Marlier et al., 2026; National Academy of Medicine, 2025; Simpson et al., 2023; Zscheischler et al., 2018). For this report, we focus on extreme heat and outdoor air quality (ozone [O3] and fine particulate matter [PM2.5]) as the main compound hazards causing compound climate events, given that 1) the state of Colorado has experienced poor air quality for some time, 2) these climate events are affecting large population numbers, and 3) there is capacity to consider and respond to these climate-driven events.

Colorado↗
USGS1996

Bibliography of selected water-resources publications on Nevada by the U.S. Geological Survey, 1885 through 1995

References to 898 water-resources publications are listed alphabetically by senior author and indexed by hydrographic-area name or other geographic features. Most of the publications were written between 1960 and 1995 by U.S. Geological Survey scientists and engineers of the Water Resources Division, Nevada District. Also included are references to publications by other Water Resources Division authors that deal with Nevada hydrology. References to publications written before 1960 are included to provide a historical perspective. The references include several types of Geological Survey book and map publications, as well as State-series reports, journal articles, conference and symposium papers, abstracts, and graduate- degree theses. Information on publication availability is provided also.

Open-File Report↗
USGS2011

Hydrogeologic settings and groundwater-flow simulations for regional investigations of the transport of anthropogenic and natural contaminants to public-supply wells—Investigations begun in 2004

A study of the Transport of Anthropogenic and Natural Contaminants to public-supply wells (TANC study) was begun in 2001 as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. The study was designed to shed light on factors that affect the vulnerability of groundwater and, more specifically, water from public-supply wells to contamination to provide a context for the NAWQA Program's earlier finding of mixtures of contaminants at low concentrations in groundwater near the water table in urban areas across the Nation. The TANC study has included investigations at both the regional (tens to thousands of square kilometers) and local (generally less than 25 square kilometers) scales. At the regional scale, the approach to investigation involves refining conceptual models of groundwater flow in hydrologically distinct settings and then constructing or updating a groundwater-flow model with particle tracking for each setting to help quantify regional water budgets, public-supply well contributing areas (areas contributing recharge to wells and zones of contribution for wells), and traveltimes from recharge areas to selected wells. A great deal of information about each contributing area is captured from the model output, including values for 170 variables that describe physical and (or) geochemical characteristics of the contributing areas. The information is subsequently stored in a relational database. Retrospective water-quality data from monitoring, domestic, and many of the public-supply wells, as well as data from newly collected samples at selected public-supply wells, also are stored in the database and are used with the model output to help discern the more important factors affecting vulnerability in many, if not most, settings. The study began with investigations in seven regional areas, and it benefits from being conducted as part of the NAWQA Program, in which consistent methods are used so that meaningful comparisons can be made. The hydrogeologic settings and regional-scale groundwater-flow models from the initial seven regional areas are documented in Chapter A of this U.S. Geological Survey Professional Paper. Also documented in Chapter A are the methods used to collect and compile the water-quality data, determine contributing areas of the public-supply wells, and characterize the oxidation-reduction (redox) conditions in each setting. A data dictionary for the database that was designed to enable joint storage and access to water-quality data and groundwater-flow model particle-tracking output is included as Appendix 1 of Chapter A. This chapter, Chapter B, documents modifications to the study methods and presents descriptions of two regional areas that were added to the TANC study in 2004.

Professional Paper↗
USGS2010

Public outreach and communications of the Alaska Volcano Observatory during the 2005-2006 eruption of Augustine Volcano: Chapter 27 in The 2006 eruption of Augustine Volcano, Alaska

The 2005-6 eruption of Augustine Volcano in the Cook Inlet region, Alaska, greatly increased public desire for volcano hazard information, as this eruption was the most significant in Cook Inlet since 1992. In response to this heightened concern, the Alaska Volcano Observatory (AVO) increased ongoing efforts to deliver specific eruption-focused information to communities nearest to the volcano, created a public communications strategy to assist staff with managing requests, and used the recently upgraded AVO Web site as a primary information-delivery path. During the eruption, AVO responded to a minimum of ~1,700 individual requests for information from the media, the public, and other organizations with responsibilities associated with volcanic activity in Alaska; requests were received both as phone calls to the observatory and e-mail stemming from the AVO Web site. Staff also delivered approximately two dozen Augustine-specific presentations and gave nearly three dozen tours of the AVO Anchorage Operations Center in Anchorage. This intensity of public interaction was markedly higher than during noneruptive periods. During the Augustine unrest and eruption, AVO also refined its internal communication procedures, instituted and maintained up-to-date and concise talking points concerning the most recent and relevant volcanic activity and hazards, and created a media management plan to assist staff in working with members of the media. These items aided staff in maintaining a consistent message concerning the eruption, potential hazards, and our response activities. The AVO Web site, with its accompanying database, is the backbone of AVO's external and internal communications. This was the first Cook Inlet volcanic eruption with a public expectation of real-time access to data, updates, and hazards information over the Internet. In March 2005, AVO improved the Web site from individual static pages to a dynamic, database-driven site. This new system provided quick and straightforward access to the latest information for (1) staff within the observatory, (2) emergency managers from State and local governments and organizations, (3) the media, and (4) the public. From mid-December 2005 through April 2006, the AVO Web site served more than 45 million Web pages and about 5.5 terabytes of data.

Alaska↗
USGS2007

Earth science and public health: Proceedings of the Second National Conference on USGS Health-Related Research

The mission of the U.S. Geological Survey (USGS) is to serve the Nation by providing reliable scientific information to describe and understand the earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life. As the Nation?s largest water, earth, and biological science and civilian mapping agency, the USGS can play a significant role in providing scientific knowledge and information that will improve our understanding of the relations of environment and wildlife to human health and disease. USGS human health-related research is unique in the Federal government because it brings together a broad spectrum of natural science expertise and information, including extensive data collection and monitoring on varied landscapes and ecosystems across the Nation. USGS can provide a great service to the public health community by synthesizing the scientific information and knowledge on our natural and living resources that influence human health, and by bringing this science to the public health community in a manner that is most useful. Partnerships with health scientists and managers are essential to the success of these efforts. USGS scientists already are working closely with the public health community to pursue rigorous inquiries into the connections between natural science and public health. Partnering agencies include the Armed Forces Institute of Pathology, Agency for Toxic Substances Disease Registry, Centers for Disease Control and Prevention, U.S. Environmental Protection Agency, Food and Drug Administration, Mine Safety and Health Administration, National Cancer Institute, National Institute of Allergy and Infectious Disease, National Institute of Environmental Health Sciences, National Institute for Occupational Safety and Health, U.S. Public Health Service, and the U.S. Army Medical Research Institute of Infectious Diseases. Collaborations between public health scientists and earth scientists can lead to improved solutions for existing and emerging environmental health problems. This report summarizes the presentations and discussions held at the Second National Conference on USGS Health-Related Research, held at the USGS national headquarters in Reston, Virginia. The report presents 68 abstracts of technical presentations made at the conference and summaries of six topical breakout sessions. The abstracts cover a broad range of issues and demonstrate connections between human health and the quality and condition of our environment and wildlife. The summaries of the topical breakout sessions present ideas for advancing interdisciplinary science in areas of earth science and human health.

Scientific Investigations Report↗
USGS2015

Hexavalent and total chromium at low reporting concentrations in source-water aquifers and surface waters used for public supply in Illinois, 2013

On the basis of their recent review of the human health effects of hexavalent chromium [Cr(VI)] in public drinking water, the U.S. Environmental Protection Agency is considering the need for Federal regulation of Cr(VI). Presently, only total chromium is regulated, at a Maximum Contaminant Level (MCL) of 100 micrograms per liter (µg/L). The occurrence of Cr(VI) in groundwater and surface waters generally is attributed to industrial sources, but can be of natural origin. California’s recently established MCL for Cr(VI) of 10 µg/L illustrates the drinking-water concerns associated with Cr(VI). To improve understanding of the possible impact of a Cr(VI)-specific standard that approximates the California level on the management of Illinois’ public drinking water, the U.S. Geological Survey, in cooperation with the Illinois Environmental Protection Agency, assessed the occurrence and distribution of Cr(VI) in the State’s public-water supplies. During 2013, untreated water samples were collected to be analyzed for Cr(VI) and total chromium [Cr(T)] at 119 water-supply wells and 32 surface-water intakes; also, 32 treated surface-water samples were collected near the point of treatment and 32 near the furthest point of distribution. Public-supply sample sites were selected by a stratified random method. Samples typically were analyzed within 24 hours of collection at reporting limits of 0.02 µg/L for Cr(VI) and 0.1 µg/L for Cr(T). The occurrence of Cr(VI) was compared with selected geophysical, physical, and sampling factors that might more fully explain its distribution and magnitude of concentrations. The maximum concentration of Cr(VI) in groundwater was 2.1 µg/L. Maximum concentrations in untreated and treated surface water were 0.29 µg/L and 2.4 µg/L, respectively. All sample concentrations were below the California MCL; only 35 percent were below that State’s non-enforceable public health goal of 0.02 of µg/L. Cr(VI) was undetected in 43 percent of untreated groundwater samples, with a median of 0.06 µg/L when detected. All but two (94 percent) of untreated surface-water samples had detections. In untreated surface water, the median concentration was 0.09 µg/L, whereas in treated (tap and distributed) water the median was 0.20 µg/L. Surface waters treated with lime for softening typically had the greatest Cr(VI) concentrations (maximum, 2.4 µg/L; median, 1.2 µg/L). The maximum concentration of Cr(T) in groundwater was 1.8 µg/L. Maximum concentrations in untreated and treated surface water were 1.8 µg/L and 2.5 µg/L, respectively. All sample concentrations were below the Federal MCL. Total chromium was detected in 65 percent of untreated groundwater samples, with a median of 0.40 µg/L, when detected. All but one (97 percent) of untreated surface-water samples had detections. In untreated surface water, the median concentration was 0.40 µg/L, whereas in treated (tap and distributed) water the median was 0.30 µg/L. As with Cr(VI), surface waters treated with lime typically had the greatest Cr(T) concentrations. Examination of factors that might account for or be associated with the occurrence of Cr(VI) in public-supply source waters found few clearly evident factors. Associations in frequencies of occurrence and range of concentrations indicate that surface waters and groundwaters of shallow, unconsolidated, unconfined aquifers, particularly alluvial aquifers, are possibly most commonly affected by anthropogenic sources of Cr(VI). Groundwaters of deep (greater than 500 feet) bedrock aquifers, particularly the Cambrian-Ordovician aquifer system, are possibly most commonly affected by geologic sources of Cr(VI). Additional study, with supporting geologic and geochemical data that were not collected in this study, would be necessary to verify these associations. There was a weak positive relation (ρ = 0.23) between concentrations of Cr(VI) and Cr(T) in untreated water samples, with a much stronger positive relation (ρ = 0.86 and ρ = 0.90, respectively) in samples collected soon after treatment and near the endpoint of distribution. The stronger relation and greater similarity between Cr(VI) and Cr(T) concentrations in treated water samples indicate that Cr(VI) represents a greater proportion of the measured concentrations of Cr(T) in treated waters than in untreated waters. The analysis of spikes and other quality-assurance samples indicate uncertainties associated with obtaining or confirming consistently accurate analytical results for Cr(VI) at near the applied reporting limit of 0.02 µg/L.

Illinois↗
USGS1964

Public water supplies of the 100 largest cities of the United States, 1962

The public water supplies of the 100 largest cities in the United States (1960 U.S. Census) serve 9,650 million gallons of water per day (mgd) to 60 million people, which is 34 percent of the Nation's total population and 48 percent of the Nation's urban population. The amount of water used to satisfy the domestic needs as well as the needs of commerce and industry ranges from 13 mgd, which serves a population of 124,000, to 1,200 mgd, which serves a city of 8 million people. The water for the public supplies of these largest cities comes fro^n ground water wells and infiltration galleries and from surface water streams, reservoirs, and lakes. Twenty of the cities use ground water exclusively for public supplies, and 14 use a combination of ground and surface waters. Sixty-six cities use surface water solely; of these cities 37 depend solely upon reservoir water, and 20 depend solely upon natural streamflow. Water from the Great Lakes furnishes part or all of the water supply for 10 of these largest cities. Hardness of water, measured in parts per million (ppm), is an important factor in the usability of water supplies. Twenty-seven cities, serving a population of 8 million, have a raw-water hardness exceeding 180 ppm ("very hard"), but only 13 cities, serving a population of 3.7 million, have a "very hard" treated-water supply; and although 22 cities, serving about 10 million people, have a raw-water hardness ranging from 121 to 180 ppm ("hard"), only 16 cities, serving a population of 11 million, have a "hard" treated-water supply. Only 16 cities, serving a population of 16 million people, have a raw-water hardness ranging from 61 to 120 ppm ("moderately hard"), whereas 41 cities, serving a population of 22 million, have a treated-water supply having a hardness within this desirable range. A few cities that have a "soft" raw water add lime to control corrosion and consequently increase their water hardness to more than 61 ppm. Thirty cities, serving a population of about 23 million, have a treated-water supply with a hardness of less than 61 ppm. The dissolved-solids content in raw-water supplies of 27 cities, which serve a total population of slightly more than 21 million people, is 100 ppr^ or less. Thirty-eight cities serving a total population of 23 million people have raw-water supplies with a dissolved-solids content between 101 and 250 ppm, whereas 48 cities, serving a population of 28 million about half the population of these 1 2 PUBLIC WATER SUPPLIES, 1962 cities furnish water having this range of dissolved solids. Twentv-nine cities serving a total population of 11 million people have raw-water supplies that contain between 251 to 500 ppm of dissolved solids. Because some o* these cities treat their water supply, 22 cities serving 8 million people furnish water having a dissolved-solids content between 251 and 500 ppm. Only six cities, serving a population of about iy2 million people, have raw-water supplies containing more than 500 ppm of dissolved solids; four of these cities soften the water and consequently reduce the dissolved-solids content. Thus, about 1 million people in three cities receive water containing more than 500 ppm of dissolved solids. Chemical analyses of treated-water supplies indicate that more than 90 percent of the supplies contain less than (a) 500 ppm of dissolved solids, (b) 100 ppm of sulfate, (c) 50 ppm each of calcium, sodium, and chloride, (d) 30 ppm of silica, (e) 20 ppm of magnesium, (f) 5 ppm each of potassium and nitrate, and (g) 1 ppm of fluoride. Spectrographic analyses, reported in micrograms per liter (/*g per 1), show that 87 percent of the treated-water supplies contain less than 500 /*g per 1 of aluminum and more than 90 percent of the supplies contain less than (a) 500 /*g per 1 of strontium, (b) 150 /*g per 1 of iron, (c) 50 ^g per 1 of lithium, (d) 10 /ug per 1 each of molybdenum, nickel, lead, and vanadium, and (e) 5 /*g per 1 each cf chromium, rubidium, and titanium. Radiochemical analyses of treated-water supplies reveal that the maximum beta activity of these supplies is 130 picocuries per liter (pc per 1) and the maximum activity due to radium content is 2.5 pe per 1, both of which are well under the recommended maximum limits for drinking water. The report is divided into two sections. The first describes the uses of water in large cities, the raw-water supplies available for public supplies, tl-<; major and minor constituents and the properties of water, the methods of analyses, the treatment of water, the effects of chemical treatment on constituents and properties of water, and the costs of water treatment. The second is a city-by-city inventory that gives (a) the population of the city, (b) the adjacent communities supplied by the city water system, (c) the total population served, (d) the sources of water supply (including auxiliary and emergency supplies), (e) the average amount of water used daily, (f) the lowest 30-day mean discharge of streams used for public supply during recent years, (g) the treatment of water, (h) the rated capacity of each water-treatment plant, and (i) the storage capacity for raw and finished water. For 58 of the cities, the sources of water, the location of water-treatment plants, and the areas served by the city system are shown on maps. Chemical, spectrographic, and radiochemical analyses of treated water and chemical and spectrographic analyses for many of the raw-water supplies are presented in tabular form.

Water Supply Paper↗