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USGS2000

Water resources data, Pennsylvania, water year 2000. Volume 2. Susquehanna and Potomac River Basins

Introduction The Water Resources Division of the U.S. Geological Survey, in cooperation with State, municipal, and Federal agencies, collects a large amount of data pertaining to the water resources of Pennsylvania each water year. These data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, these data are published annually in this report series entitled "Water Resources Data - Pennsylvania, Volumes 1, 2, and 3." Volume 1 contains data for the Delaware River Basin; Volume 2, the Susquehanna and Potomac River Basins; and Volume 3, the Ohio and St. Lawrence River Basins. This report, Volume 2, contains: (1) discharge records for 83 continuous-record streamflow-gaging stations, 16 partial-record stations, and 24 special study and miscellaneous streamflow sites; (2) elevation and contents records for 12 lakes and reservoirs; (3) water-quality records for 11 streamflow gaging stations and 70 partial-record and project stations; and (4) water-level records for 30 ground-water network observation wells and water-quality analyses of ground water from 8 wells; and (5) water-quality analyses at 60 special study ground-water wells. Additional water data collected at various sites not involved in the systematic data-collection program may also be presented. Publications similar to this report are published annually by the Geological Survey for all States. For the purpose of archiving, these official reports have an identification number consisting of the two-letter State abbreviation, the last two digits of the water year, and the volume number. For example, this volume is identified as "U.S. Geological Survey Water-Data Report PA-00-2." These water-data reports, beginning with the 1971 water year, are for sale as paper copy or microfiche by the National Technical Information Service, U.S. Department of Commerce, Springfield, VA 22161. The annual series of Water Data Reports for Pennsylvania began with the 1961 water-year report and contained only data relating to quantities of surface water. With the 1964 water year, a companion report (part 2) was introduced that contained only data relating to water quality. Beginning with the 1975 water year the report was changed to three volumes (by river basin), with each volume containing data on quantities of surface water, quality of surface and ground water, and ground-water levels. Prior to the introduction of this series and for several years concurrent with it, water-resources data for Pennsylvania were published in U.S. Geological Survey Water-Supply Papers. Data on stream discharge and stage, and on lake or reservoir contents and stage, through September 1960, were published annually under the title "Surface-Water Supply of the United States," which was released in numbered parts as determined by natural drainage basins. For the 1961-70 water years, these data were published in two 5-year reports. Data prior to 1961 are included in two reports: "Compilation of Records of Surface Waters of the United States through 1950," and "Compilation of Records of Surface Waters of the United States, October 1950 to September 1960." Data for Pennsylvania are published in Parts 1, 3, and 4. Data on chemical quality, temperature, and suspended sediment for the 1941-70 water years were published annually under the title "Quality of Surface Waters of the United States," and ground-water levels for the 1935-74 water years were published annually under the title "Ground-Water Levels in the United States." The above mentioned Water-Supply Papers may be consulted in the libraries of the principal cities of the United States and may be purchased from the U.S. Geological Survey, Information Services, Box 25286, Denver, CO 80225. Information for ordering specific reports may be obtained from the Pennsylvania District Office at the address on the back of the title page or by phoning the Scientific and Technical Products Section at (717) 730-6940. Information on the availability of unpublished data or statistical analyses may be obtained from the District Information Specialist by telephone at (717) 730-6916 or by FAX at (717) 730-6997.

Water Data Report↗

USGS2001

Water Resources Data, Pennsylvania, Water Year 2001, Volume 2. Susquehanna and Potomac River Basins

Introduction The Water Resources Division of the U.S. Geological Survey, in cooperation with State, municipal, and Federal agencies, collects a large amount of data pertaining to the water resources of Pennsylvania each water year. These data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, these data are published annually in this report series entitled "Water Resources Data - Pennsylvania, Volumes 1, 2, and 3." Volume 1 contains data for the Delaware River Basin; Volume 2, the Susquehanna and Potomac River Basins; and Volume 3, the Ohio and St. Lawrence River Basins. This report, Volume 2, contains: (1) discharge records for 83 continuous-record streamflow-gaging stations, 15 partial-record stations, and 24 special study and miscellaneous streamflow sites; (2) elevation and contents records for 12 lakes and reservoirs; (3) water-quality records for 9 streamflow gaging stations and 73 partial-record and project stations; and (4) water-level records for 36 ground-water network observation wells and water-quality analyses of ground water from 8 wells; (5) water-quality analyses at 123 special study ground-water wells; and, (6) miscellaneous water-level measurements at 80 special study ground-water wells. Additional water data collected at various sites not involved in the systematic data-collection program may also be presented. Publications similar to this report are published annually by the Geological Survey for all States. For the purpose of archiving, these official reports have an identification number consisting of the two-letter State abbreviation, the last two digits of the water year, and the volume number. For example, this volume is identified as "U.S. Geological Survey Water-Data Report PA-01-2." These water-data reports, beginning with the 1971 water year, are for sale as paper copy or microfiche by the National Technical Information Service, U.S. Department of Commerce, Springfield, VA 22161. The annual series of Water Data Reports for Pennsylvania began with the 1961 water-year report and contained only data relating to quantities of surface water. With the 1964 water year, a companion report (part 2) was introduced that contained only data relating to water quality. Beginning with the 1975 water year the report was changed to three volumes (by river basin), with each volume containing data on quantities of surface water, quality of surface and ground water, and ground-water levels. Prior to the introduction of this series and for several years concurrent with it, water-resources data for Pennsylvania were published in U.S. Geological Survey Water-Supply Papers. Data on stream discharge and stage, and on lake or reservoir contents and stage, through September 1960, were published annually under the title "Surface-Water Supply of the United States," which was released in numbered parts as determined by natural drainage basins. For the 1961-70 water years, these data were published in two 5-year reports. Data prior to 1961 are included in two reports: "Compilation of Records of Surface Waters of the United States through 1950," and "Compilation of Records of Surface Waters of the United States, October 1950 to September 1960." Data for Pennsylvania are published in Parts 1, 3, and 4. Data on chemical quality, temperature, and suspended sediment for the 1941-70 water years were published annually under the title "Quality of Surface Waters of the United States," and ground-water levels for the 1935-74 water years were published annually under the title "Ground-Water Levels in the United States." The above mentioned Water-Supply Papers may be consulted in the libraries of the principal cities of the United States and may be purchased from the U.S. Geological Survey, Information Services, Box 25286, Denver, CO 80225. Information for ordering specific reports may be obtained from the Pennsylvania District Office at the address on the back of the title page or by phoning the Scientific and Technical Products Section at (717) 730-6940. Information on the availability of unpublished data or statistical analyses may be obtained from the District Information Specialist by telephone at (717) 730-6916 or by FAX at (717) 730-6997.

Water Data Report↗

USGS2006

FGDC Digital Cartographic Standard for Geologic Map Symbolization (PostScript Implementation)

PLEASE NOTE: This now-approved 'FGDC Digital Cartographic Standard for Geologic Map Symbolization (PostScript Implementation)' officially supercedes its earlier (2000) Public Review Draft version (see 'Earlier Versions of the Standard' below). In August 2006, the Digital Cartographic Standard for Geologic Map Symbolization was officially endorsed by the Federal Geographic Data Committee (FGDC) as the national standard for the digital cartographic representation of geologic map features (FGDC Document Number FGDC-STD-013-2006). Presented herein is the PostScript Implementation of the standard, which will enable users to directly apply the symbols in the standard to geologic maps and illustrations prepared in desktop illustration and (or) publishing software. The FGDC Digital Cartographic Standard for Geologic Map Symbolization contains descriptions, examples, cartographic specifications, and notes on usage for a wide variety of symbols that may be used on typical, general-purpose geologic maps and related products such as cross sections. The standard also can be used for different kinds of special-purpose or derivative map products and databases that may be focused on a specific geoscience topic (for example, slope stability) or class of features (for example, a fault map). The standard is scale-independent, meaning that the symbols are appropriate for use with geologic mapping compiled or published at any scale. It will be useful to anyone who either produces or uses geologic map information, whether in analog or digital form. Please be aware that this standard is not intended to be used inflexibly or in a manner that will limit one's ability to communicate the observations and interpretations gained from geologic mapping. In certain situations, a symbol or its usage might need to be modified in order to better represent a particular feature on a geologic map or cross section. This standard allows the use of any symbol that doesn't conflict with others in the standard, provided that it is clearly explained on the map and in the database. In addition, modifying the size, color, and (or) lineweight of an existing symbol to suit the needs of a particular map or output device also is permitted, provided that the modified symbol's appearance is not too similar to another symbol on the map. Be aware, however, that reducing lineweights below .125 mm (.005 inch) may cause symbols to plot incorrectly if output at higher resolutions (1800 dpi or higher). For guidelines on symbol usage, as well as on color design and map labeling, please refer to the standard's introductory text. Also found there are informational sections covering concepts of geologic mapping and some definitions of geologic map features, as well as sections on the newly defined concepts and terminology for the scientific confidence and locational accuracy of geologic map features. More information on both the past development and the future maintenance of the FGDC Digital Cartographic Standard for Geologic Map Symbolization can be found at the FGDC Geologic Data Subcommittee website (http://ngmdb.usgs.gov/fgdc_gds/). Earlier Versions of the Standard

Techniques and Methods↗

USGS2001

Water resources data, Pennsylvania, water year 2000, Volume 1. Delaware River Basin

The Water Resources Division of the U.S. Geological Survey, in cooperation with State, municipal, and Federal agencies, collects a large amount of data pertaining to the water resources of Pennsylvania each water year. These data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, these data are published annually in this report series entitled "Water Resources Data - Pennsylvania, Volumes 1, 2, and 3." Volume 1 contains data for the Delaware River Basin; Volume 2, the Susquehanna and Potomac River Basins; and Volume 3, the Ohio River and St. Lawrence River Basins. This report, Volume 1, contains: (1) discharge records for 76 continuous-record streamflow-gaging stations, 7 partial-record stations, and 13 special study and miscellaneous streamflow sites; (2) elevation and contents records for 14 lakes and reservoirs; (3) water-quality records for 28 gaging stations and 14 ungaged streamsites; (4) water-quality records for 77 special-study stations; (5) water-level records for 53 network observation wells; and (6) water-quality analyses of ground water from 101 ground-water wells. Additional water data collected at various sites not involved in the systematic data-collection program may also be presented. Publications similar to this report are published annually by the Geological Survey for all States. For the purpose of archiving, these official reports have an identification number consisting of the two-letter State abbreviation, the last two digits of the water year, and the volume number. For example, this volume is identified as "U.S. Geological Survey Water-Data Report PA-00-1." These water data reports, beginning with the 1971 water year, are for sale as paper copy or microfiche by the National Technical Information Service, U.S. Department of Commerce, Springfield, VA 22161. The annual series of Water Data Reports for Pennsylvania began with the 1961 water-year report and contained only data relating to quantities of surface water. With the 1964 water year, a companion report (part 2) was introduced that contained only data relating to water quality. Beginningwith the 1975 water year the report was changed to its present format of three volumes (by river basin), with each volume containing data on quantities of surface water, quality of surface and ground water, and ground-water levels. Prior to the introduction of this series and for several years concurrent with it, water-resources data for Pennsylvania were published in U.S. Geological Survey Water-Supply Papers. Data on stream discharge and stage, and on lake or reservoir contents and stage, through September 1960, were published annually under the title "Surface-Water Supply of the United States," which was released in numbered parts as determined by natural drainage basins. For the 1961-70 water years, these data were published in two 5-year reports. Data prior to 1961 are included in two reports: "Compilation of Records of Surface Waters of the United States through 1950," and "Compilation of Records of Surface Waters of the United States, October 1950 to September 1960." Data for Pennsylvania are published in Parts 1, 3, and 4. Data on chemical quality, temperature, and suspended sediment for the 1941-70 water years were published annually under the title "Quality of Surface Waters of the United States," and ground-water levels for the 1935-74 water years were published under the title "Ground-Water Levels in the United States." The above mentioned Water-Supply Papers may be consulted in the libraries of the principal cities of the United States and may be purchased from the U.S. Geological Survey, Information Services, Box 25286, Denver, CO 80225. Information for ordering specific reports may be obtained from the Pennsylvania District Office at the address given on the back of the title page or by phoning the Scientific and Technical Products Section, at (717) 730-6940. Information on the availability of unpublished data or statistical analyses may be obtained from the District Information Specialist by telephone at (717) 730-6916 or by FAX at (717) 730-6997.

Water Data Report↗

USGS2025

Selected special conditions affecting peak streamflow and extreme floods in Alaska through water year 2022

The U.S. Geological Survey, in cooperation with the Alaska Department of Transportation and Public Facilities, inventoried selected special conditions for annual peak flows and identified extreme floods at streamgages in Alaska through water year 2022 to facilitate hydrologic analysis. Special conditions identified from U.S. Geological Survey gaging records and basin characteristics included regulation and diversion, urbanization, indeterminate drainage areas, drainage areas less than the minimum used in regional analyses, glacial lake outburst floods, other outburst floods, and snowmelt floods. For peak flows that occurred during calendar years 1980–2019, an atmospheric river dataset was used to identify atmospheric river presence or absence on the dates peak flows occurred. Extreme floods (defined as peak flows exceeding the 1-percent annual exceedance probability flood magnitude or an empirical measure of relative magnitude using Creager’s coefficient C) were identified and associated with flood-generating mechanisms using the other inventoried special conditions and other information. The gaging record contained glacial lake outburst floods at 15 streamgages and other types of outburst floods at 10 streamgages. Non-outburst peak flows in Alaska resulted from a mixture of rainfall and melt-based flood-generating mechanisms in all but the most rain-dominated seasonal flow regime. Melt-based flood-generating mechanisms included snowmelt, high-elevation snow and ice melt, or rain-on-snow events. Atmospheric rivers were common in Alaska and conterminous basins in Canada, occurring in that region on 67 percent of the days in the calendar year 1980–2019 period. Atmospheric rivers were more common on the days of peak flows and even more common on the days of non-outburst extreme floods. The percentage of days when an atmospheric river was present increased to 78 percent for the days of peak flows in that period and to 83 percent for the days of non-outburst extreme floods in that period. Of 149 extreme floods in the gaging record, 38 were generated by outburst floods. Of the non-outburst extreme floods, 72 percent were generated by rainfall and 26 percent were generated by melt-based processes or a combination of rainfall and melt-based processes. Flood-generating mechanisms could not be determined for the final 2 percent of the non-outburst extreme floods because the month and day of the peak flows were unknown and no other information was available. Secondary factors strongly associated with extreme floods included antecedent rain and streamflow conditions and warm storm conditions that produced rain instead of snow or generated snowmelt.

Alaska↗

USGS2001

Water resources data, Pennsylvania, water year 2000. Volume 3. Ohio and St. Lawrence River Basins

Introduction The Water Resources Division of the U.S. Geological Survey, in cooperation with State, municipal, and Federal agencies, collects a large amount of data pertaining to the water resources of Pennsylvania each water year. These data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, these data are published annually in this report series entitled "Water Resources Data - Pennsylvania, Volumes 1, 2, and 3." Volume 1 contains data for the Delaware River Basin; Volume 2, the Susquehanna and Potomac River Basins; and Volume 3, the Ohio and St. Lawrence River Basins. This report, Volume 3, contains: (1) discharge records for 58 continuous-record streamflow-gaging stations, 5 partial-record stations, and 12 special study and miscellaneous streamflow sites; (2) elevation and contents records for 11 lakes and reservoirs; (3) water-quality records for 1 streamflow gaging station and 8 ungaged streamsites; and (4) water-level records for 15 ground-water network observation wells and. Additional water data collected at various sites not involved in the systematic data-collection program may also be presented. Publications similar to this report are published annually by the Geological Survey for all States. For the purpose of archiving, these official reports have an identification number consisting of the two-letter State abbreviation, the last two digits of the water year, and the volume number. For example, this volume is identified as "U.S. Geological Survey Water-Data Report PA-00-3." These water-data reports, beginning with the 1971 water year, are for sale as paper copy or microfiche by the National Technical Information Service, U.S. Department of Commerce, Springfield, VA 22161. The annual series of Water Data Reports for Pennsylvania began with the 1961 water-year report and contained only data relating to quantities of surface water. With the 1964 water year, a companion report (part 2) was introduced that contained only data relating to water quality. Beginning with the 1975 water year the report was changed to three volumes (by river basin), with each volume containing data on quantities of surface water, quality of surface and ground water, and ground-water levels. Prior to the introduction of this series and for several years concurrent with it, water-resources data for Pennsylvania were published in U.S. Geological Survey Water-Supply Papers. Data on stream discharge and stage, and on lake or reservoir contents and stage, through September 1960, were published annually under the title "Surface-Water Supply of the United States," which was released in numbered parts as determined by natural drainage basins. For the 1961-70 water years, these data were published in two 5-year reports. Data prior to 1961 are included in two reports: "Compilation of Records of Surface Waters of the United States through 1950," and "Compilation of Records of Surface Waters of the United States, October 1950 to September 1960." Data for Pennsylvania are published in Parts 1, 3, and 4. Data on chemical quality, temperature, and suspended sediment for the 1941-70 water years were published annually under the title "Quality of Surface Waters of the United States," and ground-water levels for the 1935-74 water years were published annually under the title "Ground-Water Levels in the United States." The above mentioned Water-Supply Papers may be consulted in the libraries of the principal cities of the United States and may be purchased from the U.S. Geological Survey, Information Services, Box 25286, Denver, CO 80225. Information for ordering specific reports may be obtained from the Pennsylvania District Office at the address on the back of the title page or by phoning the Scientific and Technical Products Section at (717) 730-6940. Information on the availability of unpublished data or statistical analyses may be obtained from the District Information Specialist by telephone at (717) 730-6916 or by FAX at (717) 730-6997.

Water Data Report↗

USGS2015

Status and understanding of groundwater quality in the Northern Coast Ranges study unit, 2009: California GAMA Priority Basin Project

Groundwater quality in the 633-square-mile (1,639-square-kilometer) Northern Coast Ranges (NOCO) study unit was investigated as part of the Priority Basin Project (PBP) of the Groundwater Ambient Monitoring and Assessment (GAMA) Program and the U.S. Geological Survey (USGS) National Water-Quality Assessment Program. The study unit is composed of two study areas (Interior Basins and Coastal Basins) and is located in northern California in Napa, Sonoma, Lake, Colusa, Mendocino, Glenn, Humboldt, and Del Norte Counties. The GAMA-PBP is being conducted by the California State Water Resources Control Board in collaboration with the USGS and the Lawrence Livermore National Laboratory. The GAMA NOCO study was designed to provide a spatially unbiased assessment of the quality of untreated (ambient) groundwater in the primary aquifer system within the study unit. The assessment is based on water-quality and ancillary data collected in 2009 by the USGS from 58 sites and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system is defined by the perforation intervals of sites listed in the CDPH water-quality database for the NOCO study unit. Groundwater quality in the primary aquifer system may differ from the quality in the shallow or deep water-bearing zones. The first component of this study, the status assessment of the current quality of the groundwater resource, was performed by using data from samples analyzed for inorganic constituents (such as trace elements and major and minor ions), organic constituents (volatile organic compounds and pesticides and pesticide degradates), the special-interest constituent perchlorate, and microbial indicators. This status assessment is intended to characterize the quality of groundwater resources in the primary aquifer system of the NOCO study unit, not the quality of treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration divided by the health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal or California regulatory or nonregulatory benchmarks for drinking-water quality. A relative-concentration greater than (>) 1.0 indicates a concentration greater than a benchmark, and a relative-concentration less than or equal to (≤) 1.0 indicates a concentration less than or equal to a benchmark. Relative-concentrations of organic constituents and perchlorate were classified as “high” (relative-concentration >1.0), “moderate” (0.1 < relative-concentration ≤1.0), or “low” (relative-concentration ≤0.1). Relative-concentrations of inorganic constituents were classified as “high” (relative-concentration >1.0), “moderate” (0.5 < relative-concentration ≤1.0), or “low” (relative-concentration ≤0.5). Aquifer-scale proportion was used as the primary metric in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion was defined as the percentage of the area of the primary aquifer system with a relative-concentration >1.0 for a particular constituent or class of constituents; the percentage is based on an aerial rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches—grid-based and spatially weighted—were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the NOCO study unit (within 90 percent confidence intervals). Inorganic constituents (one or more) with health-based benchmarks were detected at high relative-concentrations in 10.3 percent and at moderate relative-concentrations in 13.8 percent of the primary aquifer system. The high aquifer-scale proportion of inorganic constituents primarily reflected high aquifer-scale proportions of boron (in 8.6 percent of the primary aquifer system), arsenic (in 3.4 percent), and barium (in 1.7 percent). Inorganic constituents with aesthetic-based benchmarks were detected at high relative-concentrations in 39.7 percent and at moderate relative-concentrations in 10.3 percent of the primary aquifer system. The constituents present at high relative-concentrations were iron (25.9 percent) and manganese (39.7 percent). Relative-concentrations of organic constituents with health-based benchmarks (one or more) were high in 0.2 percent, moderate in 1.7 percent, and low in 39.7 percent of the primary aquifer system. Organic constituents were not detected in 58.4 percent of the primary aquifer system. Of the 168 organic constituents analyzed, 11 constituents were detected. Two organic constituents had detection frequencies >10 percent: the trihalomethane chloroform and the herbicide simazine. For the 10 detected organic constituents that had health-based benchmarks, nearly all detections had low relative-concentrations. The special-interest constituent perchlorate was detected at moderate relative-concentrations in 1.7 percent and at low relative-concentrations in 22.4 percent of the primary aquifer system. Perchlorate was not detected in 75.9 percent of the primary aquifer system. The second component of this study, the understanding assessment , evaluated relations between constituent concentrations and values of selected potential explanatory factors to identify the factors potentially affecting the concentrations and occurrences of constituents found at high relative-concentrations or, for organic constituents, with detection frequencies >10 percent. The potential explanatory factors evaluated were land use (including density of septic tanks and leaking or formerly leaking underground fuel tanks), well construction (well depth and depth to the top of the perforated interval in the well), hydrologic conditions (aridity index, field water temperature, and distance to nearest hot spring and geothermal well), pH, dissolved oxygen concentration, study area, groundwater age distribution, and geochemical conditions. High and moderate relative-concentrations of boron primarily occurred in the Interior Basins study area and may be attributed to groundwater interacting with hydrothermal systems. High and moderate relative-concentrations of boron were associated with elevated groundwater temperatures, groundwater chemistry characteristics similar to those of geothermal waters, and distance to known geothermal areas. Boron concentrations generally were higher where low dissolved oxygen concentrations or anoxic conditions exist. High and moderate relative-concentrations of arsenic predominantly occur in the Interior Basins study area under reducing conditions. Arsenic concentrations also may be influenced by hydrothermal systems (when present). Chloroform, simazine, and perchlorate were observed in the Interior Basins and Coastal Basins study areas, predominantly at shallow sites with top-of-perforation depths ≤70 feet below land surface, with modern water (post-1950s), and with oxic groundwater conditions.

California↗

USGS2011

Status and understanding of groundwater quality in the Monterey Bay and Salinas Valley Basins, 2005-California GAMA Priority Basin Project

Groundwater quality in the approximately 1,000 square mile (2,590 km2) Monterey Bay and Salinas Valley Basins (MS) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in central California in Monterey, Santa Cruz, and San Luis Obispo Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA MS study was designed to provide a spatially unbiased assessment of the quality of untreated (raw) groundwater in the primary aquifer systems (hereinafter referred to as primary aquifers). The assessment is based on water-quality and ancillary data collected in 2005 by the USGS from 97 wells and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifers were defined by the depth intervals of the wells listed in the CDPH database for the MS study unit. The quality of groundwater in the primary aquifers may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. The first component of this study, the status of the current quality of the groundwater resource, was assessed by using data from samples analyzed for volatile organic compounds (VOC), pesticides, and naturally occurring inorganic constituents, such as major ions and trace elements. This status assessment is intended to characterize the quality of groundwater resources in the primary aquifers of the MS study unit, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration divided by the health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal and (or) California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration greater than (>) 1.0 indicates a concentration greater than a benchmark, and less than or equal to (≤) 1.0 indicates a concentration less than or equal to a benchmark. Relative-concentrations of organic and special interest constituents [perchlorate, N-nitrosodimethylamine (NDMA), and 1,2,3-trichloropropane (1,2,3-TCP)], were classified as "high" (relative-concentration > 1.0), "moderate" (0.1 < relative-concentration ≤ 1.0), or "low" (relative-concentration ≤ 0.1). Relative-concentrations of inorganic constituents were classified as "high" (relative-concentration > 1.0), "moderate" (0.5 < relative-concentration ≤ 1.0), or "low" (relative-concentration ≤ 0.5). Aquifer-scale proportion was used as the primary metric in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion was defined as the percentage of the area of the primary aquifers with a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the percentage of the primary aquifers with moderate and low relative-concentrations, respectively. Two statistical approaches-grid-based and spatially weighted-were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially-weighted estimates were comparable in the MS study unit (within 90-percent confidence intervals). Inorganic constituents with human-health benchmarks were detected at high relative-concentrations in 14.5 percent of the primary aquifers, moderate in 35.5 percent, and low in 50.0 percent. High aquifer-scale proportion of inorganic constituents primarily reflected high aquifer-scale proportions of nitrate (7.9 percent), molybdenum (2.9 percent), arsenic (2.8 percent), boron (1.9 percent), and gross alpha-beta radioactivity (1.5 percent). Relative-concentrations of organic constituents (one or more) were high in 0.2 percent, moderate in 6.6 percent, and low in 93.2 percent (not detected in 48.1 percent) of the primary aquifers. The high aquifer-scale proportion of organic constituents primarily reflected high aquifer-scale proportions of tetrachloroethene (0.1 percent) and methyl tert-butyl ether (0.1 percent). Relative-concentration for inorganic constituents with secondary maximum contaminant levels, manganese, total dissolved solids, iron, sulfate, and chloride were high in 18.6, 8.6, 7.1, 2.9, and 1.4 percent of the primary aquifers, respectively. Of the 205 organic and special-interest constituents analyzed, 32 constituents were detected. One organic constituent, the herbicide simazine, was frequently detected (in 10 percent or more of samples), but was detected at low relative-concentrations. The second component of this study, the understanding assessment, identified the natural and human factors that affect groundwater quality by evaluating land use, physical characteristics of the wells, and geochemical conditions of the aquifer. Results from these evaluations were used to explain the occurrence and distribution of constituents in the study unit. The understanding assessment indicated that most wells that contained nitrate were classified as being in agricultural land-use areas, and depths to the top of perforations in most of the wells were less than 350 ft (76 m). High and moderate relative-concentrations of arsenic may be attributed to reductive dissolution of manganese or iron oxides, or to desorption or inhibition of arsenic sorption under alkaline conditions. Arsenic concentrations increased with increasing groundwater depth and residence time (age). Simazine was detected more often in groundwater from wells with surrounding land use classified as agricultural or urban, and with top of perforation depths less than 200 ft (61 m), than in groundwater from wells with natural land use or with deeper depths. Tritium, helium-isotope, and carbon-14 data were used to classify the predominant age of groundwater samples into three categories: modern (water that has entered the aquifer since 1953), pre-modern (water that entered the aquifer prior to 1953 to tens of thousands of years ago), and mixed (mixtures of modern- and pre-modern-age waters). Arsenic concentrations were significantly greater in groundwater with pre-modern age classification than in groundwater with modern-age classification, suggesting that arsenic accumulates with groundwater residence time.

Scientific Investigations Report↗

USGS2010

Eruptions of Hawaiian volcanoes—Past, present, and future

Viewing an erupting volcano is a memorable experience, one that has inspired fear, superstition, worship, curiosity, and fascination since before the dawn of civilization. In modern times, volcanic phenomena have attracted intense scientific interest because they provide the key to understanding processes that have created and shaped more than 80 percent of the Earth’s surface. The active Hawaiian volcanoes have received special attention worldwide because of their frequent spectacular eruptions, which often can be viewed and studied with relative ease and safety. In January 1987, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO), then located on the caldera rim of Kīlauea, celebrated its 75th anniversary. To honor this anniversary, the U.S. Geological Survey (USGS) published Professional Paper 1350 , a comprehensive summary of the many studies on Hawaiian volcanism by USGS and other scientists through the mid-1980s. Drawing from the wealth of data contained in that volume, the USGS also published in 1987 the original edition of this general-interest booklet, focusing on selected aspects of the eruptive history, style, and products of two of the State of Hawaii’s active volcanoes—Kīlauea and Mauna Loa. A second edition of the booklet was published in 2010 to commemorate the Centennial of HVO (which occurred in January 2012), summarizing abundant new information gained since the January 1983 onset of Kīlauea’s middle East Rift Zone eruption at Pu‘u‘ō‘ō and the March 2008 beginning of Kīlauea’s summit lava-lake activity within Halema‘uma‘u. In this third edition, we include highlights from Kīlauea’s subsequent activity, including the 2018 eruption in the lower East Rift Zone—the largest and most destructive in at least 200 years—and associated summit-collapse events, the eruptions at Kīlauea’s summit since 2018, and the 2022 eruption of Mauna Loa, which occurred after 38 years of quiescence. It also considers new data leading to an improved history of Kīlauea’s explosive activity in the recent geologic past. This general-interest booklet is a companion to the one on Mount St. Helens volcano (southwestern Washington) first published in 1984, revised in 1990. Together, these publications illustrate the contrast between the two main types of volcanoes: shield volcanoes, such as those in the State of Hawaii, which generally are nonexplosive to weakly explosive; and composite volcanoes, such as Mount St. Helens in the Cascade Range, which generally erupt explosively.

Hawaii↗

USGS2015

Documenting 35 years of land cover change: Lago Cachet Dos drainage, Chile

The U.S. Geological Survey (USGS) Special Applications Science Center is monitoring temporal changes at the Colonia Glacier and Lago Cachet Dos, Northern Patagonia Icefield of southern Chile. This location is one of the newest international sites in the USGS Global Fiducial Program (GFP)—a program which provides systematic monitoring of dynamic and environmentally critical areas with high-resolution imagery (http://gfp.usgs.gov/). In 2008, Lago Cachet Dos began experiencing glacial lake outburst floods (GLOFs) during which the entire pool of water (about 200 million cubic meters) rapidly drains from the lake and flows south-southeast through the Colonia Glacier. These catastrophic events cause massive erosion of valley-fill deposits and consequent upstream expansion of Lago Cachet Dos towards Lago Cachet Uno. Panchromatic and multispectral images for 1979, 2007, and 2014 highlight the dramatic changes that have occurred at this site over a 35-year period. The lake was smallest in 1979, when the Colonia Glacier was at its maximum extent during the study period. Between 1979 and 2007, the glacier shrank causing an increase in the surface area of the lake. The size of the lake increased substantially, from 2.98 square kilometers (km 2 ) in 1979 to 4.41 km 2 in 2014, primarily due to erosion of valley-fill deposits upstream of its northern edge by the 15 GLOFs that occurred between April 2008 and February 2014. Ongoing studies of the Colonia Glacier and Lago Cachet Dos are focused on providing real-time monitoring of Lago Cachet Dos lake levels, understanding the history of advances and retreats of the Colonia Glacier, and determining the physical mechanisms and hazards associated with the GLOFs that come from Lago Cachet Dos.

Lago Cachet Dos↗

USGS2010

A method for assessing carbon stocks, carbon sequestration, and greenhouse-gas fluxes in ecosystems of the United States under present conditions and future scenarios

he Energy Independence and Security Act of 2007 (EISA), Section 712, mandates the U.S. Department of the Interior to develop a methodology and conduct an assessment of the Nation’s ecosystems, focusing on carbon stocks, carbon sequestration, and emissions of three greenhouse gases (GHGs): carbon dioxide, methane, and nitrous oxide. The major requirements include (1) an assessment of all ecosystems (terrestrial systems, such as forests, croplands, wetlands, grasslands/shrublands; and aquatic ecosystems, such as rivers, lakes, and estuaries); (2) an estimate of the annual potential capacities of ecosystems to increase carbon sequestration and reduce net GHG emissions in the context of mitigation strategies (including management and restoration activities); and (3) an evaluation of the effects of controlling processes, such as climate change, land-use and land-cover change, and disturbances such as wildfires. The concepts of ecosystems, carbon pools, and GHG fluxes follow conventional definitions in use by major national and international assessment or inventory efforts. In order to estimate current ecosystem carbon stocks and GHG fluxes and to understand the potential capacity and effects of mitigation strategies, the method will use two time periods for the assessment: 2001 through 2010, which establishes a current ecosystem carbon and GHG baseline and will be used to validate the models; and 2011 through 2050, which will be used to assess potential capacities based on a set of scenarios. The scenario framework will be constructed using storylines of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES), along with both reference and enhanced land-use and land-cover (LULC) and land-management parameters. Additional LULC and land-management mitigation scenarios will be constructed for each storyline to increase carbon sequestration and reduce GHG fluxes in ecosystems. Input from regional experts and stakeholders will be solicited to construct these scenarios. The methods for mapping the current LULC and ecosystem disturbances will require the extensive use of both remote-sensing data and field-survey data (for example, forest inventories) to capture and characterize landscape-changing events. For potential LULC changes and ecosystem disturbances, key drivers such as socioeconomic and climate changes will be used in addition to the biophysical data. The result of these analyses will be a series of maps for each future year for each scenario. These annual maps will form the basis for estimating carbon storage and GHG emissions. For terrestrial ecosystems, carbon storage, carbon-sequestration capacities, and GHG emissions under the present conditions and future scenarios will be assessed using the LULC-change and ecosystem-disturbance estimates in map format with a spatially explicit biogeochemical ensemble modeling system that incorporates properties of management activities (such as tillage or harvesting) and properties of individual ecosystems (such as energy exchange, vegetation characteristics, hydrological cycling, and soil attributes). For aquatic ecosystems, carbon burial in sediments and fluxes of GHG are functions of the present and future potential stream flow and sediment transport and will be assessed using empirical hydrological modeling methods. Validation and uncertainty analysis methods described in the methodology will follow established guidelines to assess the quality of the assessment results. The U.S. Environmental Protection Agency’s Level II ecoregions map will be the practical instrument for developing and delivering assessment results. Consequently, the ecoregion (there are 22 modified ecoregions) will be the reporting unit of the assessment because the scenarios, assessment results, validation, and uncertainty analysis will be produced at that scale. The implementation of these methods will require collaborations among various Federal agencies, State agencies, nongovernmental organizations, and the science community. Using the method described in this document, the assessment can be completed in approximately 3 to 4 years. The primary deliverables will be assessment reports containing tables, charts, and maps that will present the estimated GHG parameters annually for 2001 through 2050 by ecosystem, pool, and scenario. The results will permit the evaluation of a range of policies, mitigation options, and research topics, such as the demographic, LULC-change, or climate-change effects on carbon stocks, carbon sequestration, and GHG fluxes in ecosystems.

Scientific Investigations Report↗

USGS2018

Department of the Interior metadata implementation guide—Framework for developing the metadata component for data resource management

The Department of the Interior (DOI) is a Federal agency with over 90,000 employees across 10 bureaus and 8 agency offices. Its primary mission is to protect and manage the Nation’s natural resources and cultural heritage; provide scientific and other information about those resources; and honor its trust responsibilities or special commitments to American Indians, Alaska Natives, and affiliated island communities. Data and information are critical in day-to-day operational decision making and scientific research. DOI is committed to creating, documenting, managing, and sharing high-quality data and metadata in and across its various programs that support its mission. Documenting data through metadata is essential in realizing the value of data as an enterprise asset. The completeness, consistency, and timeliness of metadata affect users’ ability to search for and discover the most relevant data for the intended purpose; and facilitates the interoperability and usability of these data among DOI bureaus and offices. Fully documented metadata describe data usability, quality, accuracy, provenance, and meaning. Across DOI, there are different maturity levels and phases of information and metadata management implementations. The Department has organized a committee consisting of bureau-level points-of-contacts to collaborate on the development of more consistent, standardized, and more effective metadata management practices and guidance to support this shared mission and the information needs of the Department. DOI’s metadata implementation plans establish key roles and responsibilities associated with metadata management processes, procedures, and a series of actions defined in three major metadata implementation phases including: (1) Getting started—Planning Phase, (2) Implementing and Maintaining Operational Metadata Management Phase, and (3) the Next Steps towards Improving Metadata Management Phase. DOI’s phased approach for metadata management addresses some of the major data and metadata management challenges that exist across the diverse missions of the bureaus and offices. All employees who create, modify, or use data are involved with data and metadata management. Identifying, establishing, and formalizing the roles and responsibilities associated with metadata management are key to institutionalizing a framework of best practices, methodologies, processes, and common approaches throughout all levels of the organization; these are the foundation for effective data resource management. For executives and managers, metadata management strengthens their overarching views of data assets, holdings, and data interoperability; and clarifies how metadata management can help accelerate the compliance of multiple policy mandates. For employees, data stewards, and data professionals, formalized metadata management will help with the consistency of definitions, and approaches addressing data discoverability, data quality, and data lineage. In addition to data professionals and others associated with information technology; data stewards and program subject matter experts take on important metadata management roles and responsibilities as data flow through their respective business and science-related workflows. The responsibilities of establishing, practicing, and governing the actions associated with their specific metadata management roles are critical to successful metadata implementation.

Techniques and Methods↗

USGS2024

Special topic—Rapid-response instrumentation

Introduction Based on the reports of Ewert and others (2005, 2018) and Moran and others (2008), most U.S. volcanoes are currently under-monitored and are likely to remain so until the goals of the National Volcano Early Warning System are fulfilled. In addition, volcanoes determined to have low to moderate threat levels (Ewert and others 2005, 2018) could awaken suddenly and, as a result, may need to have instrumentation installed rapidly. For these reasons, equipment caches would ideally be readily available for rapid response in the event of unrest at under-monitored volcanoes or during a volcanic crisis. Given that volcanoes in Alaska and Hawai‘i are frequently active, it is likely that several U.S. volcanoes could experience unrest simultaneously, as happened in 2018, 2019, and 2020, when unrest or eruptions occurred at Great Sitkin Volcano, Alaska; Mauna Loa, Hawai‘i; Mount Cleveland, Alaska; Semisopochnoi Island, Alaska; Shishaldin Volcano, Alaska; Mount Veniaminof, Alaska, as well as the most destructive documented eruption of Kīlauea, Hawai‘i. Therefore, we recommend that sufficient numbers of seismometers, infrasound sensors, Global Navigation Satellite System (GNSS) receivers, remote cameras, gas-monitoring instruments, and airborne and ground-based remote-sensing systems be made available and placed in a state of readiness at each observatory with the capability of bringing a level-2 monitoring network to near level-4 readiness. These rapid-response caches would ideally include sufficient equipment to provide real-time data telemetry, including satellite telemetry, where available, applicable, and appropriate. Rapid-response caches would be maintained in a state of readiness so that instruments can be deployed within several hours to days. Although the primary focus of the caches would be to enable rapid increases to a volcano observatory’s real-time monitoring capabilities, not all scenarios of volcanic unrest are conducive to rapid deployment of real-time data telemetry. Non-telemetered, campaign instruments, particularly seismometers and GNSS stations, can also be deployed to aid in detection of early signs of volcanic unrest given the data can be recovered in a timely fashion. Given the geographic separation of the U.S. Geological Survey Volcano Science Center’s (VSC) four volcano observatory offices, the logistical difficulties in shipping equipment rapidly between them in response to unrest, the possible scenario that a volcano could reawaken with just hours or days of precursory unrest, and the difference in operating environments (for example, tropical Hawai‘i compared to subarctic Alaska), we recommend three rapid-response instrument caches—for Hawai‘i, Alaska, and the lower 48 States. For the lower 48 States, a single cache shared among the Cascades Volcano Observatory, Yellowstone Volcano Observatory, and the California Volcano Observatory could be warehoused in California or Washington. Although these rapid-response caches would be located at one of the observatories, they would ideally be owned and maintained by VSC, and together form a flexible VSC-wide instrument pool. To maintain continuity of monitoring capabilities, this rapid-response cache could also serve to replace instruments destroyed during an on-going eruption. However, to retain eruption-response readiness, we recommend instruments in the rapid-response cache not be permanently reallocated to an observatory’s monitoring network unless they are replaced.

Scientific Investigations Report↗

USGS2014

Monitoring recharge in areas of seasonally frozen ground in the Columbia Plateau and Snake River Plain, Idaho, Oregon, and Washington

Seasonally frozen ground occurs over approximately one‑third of the contiguous United States, causing increased winter runoff. Frozen ground generally rejects potential groundwater recharge. Nearly all recharge from precipitation in semi-arid regions such as the Columbia Plateau and the Snake River Plain in Idaho, Oregon, and Washington, occurs between October and March, when precipitation is most abundant and seasonally frozen ground is commonplace. The temporal and spatial distribution of frozen ground is expected to change as the climate warms. It is difficult to predict the distribution of frozen ground, however, because of the complex ways ground freezes and the way that snow cover thermally insulates soil, by keeping it frozen longer than it would be if it was not snow covered or, more commonly, keeping the soil thawed during freezing weather. A combination of satellite remote sensing and ground truth measurements was used with some success to investigate seasonally frozen ground at local to regional scales. The frozen-ground/snow-cover algorithm from the National Snow and Ice Data Center, combined with the 21-year record of passive microwave observations from the Special Sensor Microwave Imager onboard a Defense Meteorological Satellite Program satellite, provided a unique time series of frozen ground. Periodically repeating this methodology and analyzing for trends can be a means to monitor possible regional changes to frozen ground that could occur with a warming climate. The Precipitation-Runoff Modeling System watershed model constructed for the upper Crab Creek Basin in the Columbia Plateau and Reynolds Creek basin on the eastern side of the Snake River Plain simulated recharge and frozen ground for several future climate scenarios. Frozen ground was simulated with the Continuous Frozen Ground Index, which is influenced by air temperature and snow cover. Model simulation results showed a decreased occurrence of frozen ground that coincided with increased temperatures in the future climate scenarios. Snow cover decreased in the future climate scenarios coincident with the temperature increases. Although annual precipitation was greater in future climate scenarios, thereby increasing the amount of water available for recharge over current (baseline) simulations, actual evapotranspiration also increased and reduced the amount of water available for recharge over baseline simulations. The upper Crab Creek model shows no significant trend in the rates of recharge in future scenarios. In these scenarios, annual precipitation is greater than the baseline averages, offsetting the effects of greater evapotranspiration in future scenarios. In the Reynolds Creek Basin simulations, precipitation was held constant in future scenarios and recharge was reduced by 1.0 percent for simulations representing average conditions in 2040 and reduced by 4.3 percent for simulations representing average conditions in 2080. The focus of the results of future scenarios for the Reynolds Creek Basin was the spatial components of selected hydrologic variables for this 92 square mile mountainous basin with 3,600 feet of relief. Simulation results from the watershed model using the Continuous Frozen Ground Index provided a relative measure of change in frozen ground, but could not identify the within-soil processes that allow or reject available water to recharge aquifers. The model provided a means to estimate what might occur in the future under prescribed climate scenarios, but more detailed energy-balance models of frozen-ground hydrology are needed to accurately simulate recharge under seasonally frozen ground and provide a better understanding of how changes in climate may alter infiltration.

Idaho;Oregon;Washington↗

USGS2018

Water-quality response to changes in phosphorus loading of the Winnebago Pool Lakes, Wisconsin, with special emphasis on the effects of internal loading in a chain of shallow lakes

The Winnebago Pool is a chain of four shallow lakes (Lake Poygan, Lake Winneconne, Lake Butte des Morts, and Lake Winnebago) that are fed primarily by the Fox and Wolf Rivers, two large agriculturally dominated rivers in Wisconsin, United States. Because the lakes have received extensive phosphorus inputs from their watershed, they have become highly eutrophic with much phosphorus in the water column as well as trapped in their sediments. Each of the four Winnebago Pool lakes has been included on the Wisconsin Department of Natural Resources impaired waters list because of their high total phosphorus concentrations, water-quality use restrictions, and excess algal growth. The study described in this report is part of a Total Maximum Daily Load investigation to determine what actions are needed to improve the water quality (trophic status) of these lakes and thus be able to be removed from the impaired waters list and restore their designated uses. As part of this study, data were collected to describe the existing water quality of the lakes, detailed phosphorus budgets were developed for each of the lakes to describe the different sources of the phosphorus, and two eutrophication models (BATHTUB and Jensen models) were used to determine how much of the phosphorus being input to the lakes needs to be reduced for the lakes to be removed from the impaired waters list and restore their designated uses. In-lake water-quality data indicated that each of the lakes had extensive vertical mixing that resulted in their water quality deteriorating throughout summer. Each of the lakes had mean summer total phosphorus concentrations exceeding 0.088 milligram per liter (mg/L), well above the 0.040 mg/L criterion for the lakes. Detailed phosphorus budgets for the lakes indicated that the primary sources of phosphorus were from their tributaries (for the most upstream lake in the Winnebago Pool–Lake Poygan) or from a combination of input from the upstream lakes and phosphorus release from the bottom sediment when only the summer months were considered (for the other three lakes). Model simulations with the BATHTUB and Jensen models indicated that (1) the lakes should have almost linear response in their total phosphorus concentrations to changes in their phosphorus inputs; (2) phosphorus inputs need to be reduced by about 60 percent to the Upper Pool Lakes and 69–73 percent to Lake Winnebago to reduce their mean summer total phosphorus concentrations to 0.040 mg/L; and (3) if all the anthropogenic phosphorus inputs to the lakes could be eliminated, their best possible mean summer total phosphorus concentrations should decrease to about 0.022–0.028 mg/L in the Upper Pool Lakes and to 0.032–0.033 mg/L in Lake Winnebago. The effects of any reduction in phosphorus loading will take many years (50 to more than 75 years) to be fully realized in lake water quality because of phosphorus release from the lake sediments. The effects of nutrient reductions in the watershed of a chain of lakes, such as the Winnebago Pool, gradually cascades down the chain, which has beneficial and detrimental effects. Any action made in the watershed of upstream lakes to reduce phosphorus inputs should improve the water quality of all downstream lakes; however, the upstream lakes delay the response in the downstream lakes, especially in lakes where internal phosphorus loading is important.

Wisconsin↗

USGS2004

Water quality, hydrology, and the effects of changes in phosphorus loading to Pike Lake, Washington County, Wisconsin, with special emphasis on inlet-to-outlet short-circuiting

Pike Lake is a 459-acre, mesotrophic to eutrophic dimictic lake in southeastern Wisconsin. Because of concern over degrading water quality in the lake associated with further development in its watershed, a study was conducted by the U.S. Geological Survey from 1998 to 2000 to describe the water quality and hydrology of the lake, quantify sources of phosphorus including the effects of short-circuiting of inflows, and determine how changes in phosphorus loading should affect the water quality of the lake. Measuring all significant water and phosphorus sources and estimating lesser sources was the method used to construct detailed water and phosphorus budgets. The Rubicon River, ungaged near-lake surface inflow, precipitation, and ground water provide 55, 20, 17, and 7 percent of the total inflow, respectively. Water leaves the lake through the Rubicon River outlet (87 percent) or by evaporation (13 percent). Total input of phosphorus to the lake was about 3,500 pounds in 1999 and 2,400 pounds in 2000. About 80 percent of the phosphorus was from the Rubicon River, about half of which came from the watershed and half from a waste-water treatment plant in Slinger, Wisconsin. Inlet-to-outlet short-circuiting of phosphorus is facilitated by a meandering segment of the Rubicon River channel through a marsh at the north end of the lake. It is estimated that 77 percent of phosphorus from the Rubicon River in monitoring year 1999 and 65 percent in monitoring year 2000 was short-circuited to the outlet without entering the main body of the lake. Simulations using water-quality models within the Wisconsin Lake Model Suite (WiLMS) indicated Pike Lake's response to 13 different phosphorus-loading scenarios. These scenarios included a base 'normal' year (2000) for which lake water quality and loading were known, six different percentage increases or decreases in phosphorus loading from controllable sources, and six different loading scenarios corresponding to specific management actions. Model simulations indicate that a 50-percent reduction in controllable loading sources would be needed to achieve a mesotrophic classification with respect to phosphorus, chlorophyll a, and Secchi depth (an index of water clarity). Model simulations indicated that short-circuiting of phosphorus from the inlet to the outlet was the main reason the water quality of the lake is good relative to the amount of loading from the Rubicon River and that changes in the percentage of inlet-to-outlet short-circuiting have a significant influence on the water quality of the lake.

Wisconsin↗

USGS2021

Status and understanding of groundwater quality in the northern Sierra Nevada foothills domestic-supply aquifer study units, 2015–17—California GAMA Priority Basin Project

Groundwater quality in the northern Sierra Nevada foothills region of California was investigated as part of California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring Assessment Priority Basin Project (GAMA-PBP). The region was divided into two study units: the Yuba-Bear watersheds (YBW) study unit and the American-Cosumnes-Mokelumne watersheds (ACMW) study unit. The GAMA-PBP made a spatially unbiased assessment of aquifer systems used for domestic drinking-water supply in the study region, which are predominantly composed of fractured, hard-rock aquifers of varying lithology. These assessments characterized the quality of raw groundwater to evaluate ambient conditions in the domestic-supply aquifer and not the quality of treated drinking water. The study included three components: (1) a status assessment , which characterized the quality of groundwater resources used for domestic drinking-water supply in the YBW and ACMW study units; (2) an understanding assessment , which evaluated natural and anthropogenic explanatory factors that could potentially affect groundwater quality in the study region; and (3) a comparative assessment between the groundwater resources used for domestic and public drinking-water supply in the study region. The status assessment was based on data collected by the GAMA-PBP from 74 sites in the YBW study unit during 2015–16 and 67 sites in the ACMW study unit from 2016 to 2017. To contextualize water-quality results, concentrations of water-quality constituents in ambient groundwater were compared to regulatory and non-regulatory benchmarks typically used by the State of California and Federal agencies as health-based or aesthetic standards for public drinking water. The status assessment used a grid-based method to estimate proportions of groundwater resources with concentrations approaching or exceeding benchmark thresholds. This method provides spatially unbiased results and allows inter-comparability with similar groundwater-quality assessments. Inorganic constituents with health-based benchmarks were present at high relative concentration (RC), meaning they exceeded the benchmark threshold, in 5.4 and 10 percent of domestic-supply aquifer systems in the YBW and ACMW study units, respectively. Inorganic constituents with aesthetic-based benchmarks were detected at high-RCs in 20 and 28 percent of the YBW and ACMW study units, respectively. The inorganic constituents present at high RC were arsenic, barium, boron, molybdenum, strontium, nitrate, adjusted gross-alpha particle activity, chloride, total dissolved solids, specific conductance, iron, manganese, and hardness. Groundwater samples were tested for presence or absence of three microbial indicators (total coliform, Escherichia coli , and Enterococci ). At least one microbial indicator was present in 26 and 28 percent of the YBW and ACMW study units, respectively. At least one organic constituent was detected in 30 and 42 percent of the YBW and ACMW study units, respectively. Organic constituents were not present at high RC, but tetrachloroethene (PCE), trichloroethene (TCE), and toluene were detected in the YBW study unit at moderate RC (between the benchmark concentration and one-tenth of the benchmark concentration). Methyl tert -butyl ether (MTBE) and chloroform were present at low RC (less than one-tenth of the benchmark concentration) in the YBW and ACMW study units with detection frequencies greater than 10 percent. Perchlorate, a constituent of special interest, was detected in 31 and 41 percent of the YBW and ACMW study units, respectively, at either low or moderate RCs. Relations among select water-quality constituents and potential explanatory factors were evaluated using statistical and graphical approaches. Nitrate, microbial indicators, and perchlorate were all correlated to elevation-dependent variables relating to climate, land use, and recharge condition. Isotopic and dissolved noble-gas tracers indicated these water-quality constituents are associated with recharge conditions associated with irrigation during the summer dry-season, which is common in areas of rural-residential or agricultural land uses. Higher concentrations of iron and manganese were primarily associated with anoxic groundwater in aquifers of metasedimentary lithology. Increased hardness was primarily associated with anoxic groundwater in aquifers of mafic-ultramafic or metavolcanics lithologies at lower elevations in the study region in the Melones fault zone. Chloroform and MTBE were associated with shallow groundwater (wells depths less than 130 m) under oxic and anoxic redox conditions, respectively. The comparative assessment evaluated differences between the aquifer systems used for domestic- and public-supply in study region based on (1) well-construction characteristics, and (2) water quality. Analysis of over 60,000 well-completion reports in the study region showed that although domestic-supply wells span the deepest depth zones in regional aquifers, median depths for public-supply wells were significantly greater than those of domestic-supply wells in both study units. Water-quality data from more than 300 public-supply wells in the study region were assessed using a spatially weighted method for calculation aquifer-scale proportions and compared with the domestic-supply assessment results. Detections of inorganic constituents at high RC and detection frequencies for organic constituents were generally similar between the domestic- and public-supply aquifer systems in both study units, with a few notable exceptions in the ACMW study unit: nitrate was greater for the public- compared to domestic-supply aquifer system and both manganese, hardness, and MTBE were greater in the domestic- compared to public-supply aquifer system. These differences are likely related to contrasting land uses, aquifer lithologies, landscape positions, and depths characterizing domestic- and public-supply wells in the ACMW study unit. Overall, fewer samples from domestic-supply wells in the northern Sierra Nevada foothills exceeded health-based benchmarks compared to aesthetic-based benchmarks for groundwater quality. Exceedences of health-based benchmarks were primarily caused by nitrate and coliform bacteria, which were associated with recharge from diverted surface water used primarily for irrigation. Exceedences of aesthetic-based benchmarks were primarily caused by iron, managanese, and hardness, which were associated with geologic factors. Regional irrigation practices and aquifer lithology can affect groundwater quality in fractured-rock aquifers in the northern Sierra Nevada foothills used for domestic drinking-water supply.

California↗

USGS2011

Status and understanding of groundwater quality in the Santa Clara River Valley, 2007-California GAMA Priority Basin Project

Groundwater quality in the approximately 460-square-mile Santa Clara River Valley study unit was investigated from April through June 2007 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is conducted by the U.S. Geological Survey (USGS) in collaboration with the California State Water Resources Control Board and the Lawrence Livermore National Laboratory. The Santa Clara River Valley study unit contains eight groundwater basins located in Ventura and Los Angeles Counties and is within the Transverse and Selected Peninsular Ranges hydrogeologic province. The Santa Clara River Valley study unit was designed to provide a spatially unbiased assessment of the quality of untreated (raw) groundwater in the primary aquifer system. The assessment is based on water-quality and ancillary data collected in 2007 by the USGS from 42 wells on a spatially distributed grid, and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined as that part of the aquifer system corresponding to the perforation intervals of wells listed in the CDPH database for the Santa Clara River Valley study unit. The quality of groundwater in the primary aquifer system may differ from that in shallow or deep water-bearing zones; for example, shallow groundwater may be more vulnerable to surficial contamination. Eleven additional wells were sampled by the USGS to improve understanding of factors affecting water quality.The status assessment of the quality of the groundwater used data from samples analyzed for anthropogenic constituents, such as volatile organic compounds (VOCs) and pesticides, as well as naturally occurring inorganic constituents, such as major ions and trace elements. The status assessment is intended to characterize the quality of untreated groundwater resources in the primary aquifers of the Santa Clara River Valley study unit, not the quality of treated drinking water delivered to consumers. Relative-concentrations (sample concentration divided by health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal and (or) California benchmarks. A relative-concentration greater than 1.0 indicates a concentration greater than a benchmark. For organic and special interest constituents, relative-concentrations were classified as high (greater than 1.0); moderate (greater than 0.1 and less than or equal to 1.0); and low (less than or equal to 0.1). For inorganic constituents, relative-concentrations were classified as high (greater than 1.0); moderate (greater than 0.5 and less than or equal to 1.0); and low (less than or equal to 0.5). Aquifer-scale proportion was used as the primary metric in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the areal percentage of the primary aquifer system with relative-concentrations greater than 1.0. Moderate and low aquifer-scale proportions are defined as the areal percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches, grid-based and spatially weighted, were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the Santa Clara River Valley study unit (within 90 percent confidence intervals). The status assessment showed that inorganic constituents were more prevalent and relative-concentrations were higher than for organic constituents. For inorganic constituents with human-health benchmarks, relative-concentrations (of one or more constituents) were high in 21 percent of the primary aquifer system areally, moderate in 30 percent, and low or not detected in 49 percent. Inorganic constituents with human-health benchmarks with high aquifer-scale proportions were nitrate (15 percent of the primary aquifer system), gross alpha radioactivity (14 percent), vanadium (3.4 percent), boron (3.2 percent), and arsenic (2.3 percent). For inorganic constituents with aesthetic benchmarks, relative-concentrations (of one or more constituents) were high in 54 percent of the primary aquifer system, moderate in 41 percent, and low or not detected in 4 percent. The inorganic constituents with aesthetic benchmarks with high aquifer-scale proportions were total dissolved solids (35 percent), sulfate (22 percent), manganese (38 percent), and iron (22 percent). In contrast, the results of the status assessment for organic constituents with human-health benchmarks showed that relative-concentrations were high in 0 percent (not detected above benchmarks) of the primary aquifer system, moderate in 2.4 percent, and low or not detected in 97 percent. Relative-concentrations of the special interest constituent, perchlorate, were moderate in 12 percent of the primary aquifer system and low or not detected in 88 percent. Relative-concentrations of two VOCs-carbon tetrachloride and trichloroethene (TCE)-were moderate in 2.4 percent of the primary aquifer system. One VOC-chloroform (water disinfection byproduct)-was detected in more than 10 percent of the primary aquifer system but at low relative-concentrations. Of the 88 VOCs and gasoline oxygenates analyzed, 71 were not detected. Pesticides were low or not detected in 100 percent of the primary aquifer system. Of the 118 pesticides and pesticide degradates analyzed, 13 were detected and 5 of those had human-health benchmarks. Two of these five pesticides-simazine and atrazine-were detected in more than 10 percent of the primary aquifer system. The second component of this study, the understanding assessment, was to identify the natural and human factors that affect groundwater quality on the basis of the evaluation of land use, physical characteristics of the wells, and geochemical conditions of the aquifer. Results from these analyses are used to explain the occurrence and distribution of selected constituents in the primary aquifer system of the Santa Clara River Valley study unit. The understanding assessment indicated that water quality varied spatially primarily in relation to depth, groundwater age, reduction-oxidation conditions, pH, and location in the regional groundwater flow system. High and moderate relative-concentrations of nitrate and low relative-concentrations of pesticides were correlated with shallow depths to top-of-perforation, and with high dissolved oxygen. Groundwater of modern and mixed ages had higher nitrate than pre-modern-age groundwater. Decreases in concentrations of total dissolved solids (TDS) and sulfate were correlated with increases in pH. This relationship probably indicates relations of these constituents with increasing depth across most of the Santa Clara River Valley study unit. Previous studies have indicated multiple sources of high concentrations of TDS and sulfate and multiple geochemical processes affecting these constituents in the Santa Clara River Valley study unit. Manganese and iron concentrations were highest in pre-modern-age groundwater at depth and in the downgradient area of the Santa Clara River Valley study unit (closest to the coastline), indicating the prevalence of reducing groundwater conditions in these aquifer zones.

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