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At least 1,243 records · Page 69Linked to original sources
USGS1953

Measurement of earth pressures by means of the flat jack test

This study deals with the principle and application of a method of measuring the stresses around a rock gallery. The measuring principle consists of cutting a drain in a gallery wall, observing the corresponding stress lessening, then restoring the initial state of stress by means of a Freyssinet flat jack. The application of this method in the Eastern iron-ore mines have given interesting results. In particular, they confirm the validity of the elastic hypothesis in these mines and enable the measurement of the stresses within them ass to be made more accurately than by the usual methods. Finally, by means of improvements, which do not unduly complicate the test performance, complete information on the elastic characteristics of the mineral may be obtained.

Open-File Report↗
USGS1995

Hydrologic data for the Fristoe Unit of the Mark Twain National Forest, southern Missouri, 1988-93

Background hydrologic data were collected from 1988 to 1993 in the Fristoe Unit of the Mark Twain National Forest. Water-quality data collected from area streams, springs, and wells were analyzed using trilinear diagrams, stiff diagrams, boxplots, and summary statistics. The water is a calcium- magnesium-bicarbonate type. Streams generally have slightly larger potassium, barium, and total organic carbon concentrations than spring or well water. Well water has larger bicarbonate and zinc concen- trations and larger variability in sodium, chloride, and nitrate concentrations than stream and spring water samples. The bulk mineralogy for streambed material is primarily coarse grain quartz. Quantitative elemental (chemistry) analysis on the less than 63 micrometer fraction of bulk material was performed. The heavy mineral concentrate in the streambed material was analyzed using semi- quantitative optical mineralogy and 37-element semi- quantitative emission spectrography. Water levels were measured in 57 area wells in the spring and fall from 1990 to 1993 to determine ground-water level fluctuations. Ground-water fluctuations ranged from less than 1.0 to 205.1 feet in these wells. Continuous water-level recorders were installed on three area wells. Depth to water ranged from 289.68 to 333.39 feet in the lower Eleven Point well, which is completed in the Ozark aquifer. Depth to water ranged from 78.73 to 90.20 feet in Ozark Lead Well 1 which is completed in the Ozark aquifer and St. Francois confining unit. Depth to water ranged from 127.53 to 135.67 feet in Ozark Lead Well 2, which is completed in the St. Francois confining unit and the St. Francois aquifer.

Open-File Report↗
USGS2006

Flow and salt transport in the Suwannee River estuary, Florida, 1999–2000: Analysis of data and three-dimensional simulations

A three-dimensional numerical model was developed to assist in the evaluation of the effects of changes in freshwater flow on the salinity regime of the lower Suwannee River, its estuary, and Suwannee Sound. Hydrodynamic and salt-transport modeling were supported by data from a comprehensive data-collection network operated in the lower Suwannee River during 1998-2000. The study area included all of the downstream-most 12 kilometers of the Suwannee River, Suwannee Sound, and part of the Gulf of Mexico. Development, calibration, and application of the hydrodynamic and salt-transport model were completed by using data primarily collected during October 1999-September 2000.

Florida↗
USGS2004

Riverbed elevations and water quality of the Missouri River at Sioux City, Iowa, 2002-03

The U.S. Geological Survey, in cooperation with the City of Sioux City, Iowa, conducted an investigation of the Missouri River, during 2002-2003, to assess changes in riverbed elevations from its confluence with the Big Sioux River, downstream to the area of the Sioux City municipal well field. Water-quality samples also were collected across the Missouri River to provide additional information on the differences between the water quality of the Missouri River and Big Sioux River in the well field area. The water supply at Sioux City, Iowa, is withdrawn from fourteen vertical wells and one horizontal collector well. Twelve vertical wells and the collector well are completed in the alluvial sand and gravel aquifer adjacent to the Missouri River at Sioux City. The well field is located on the left bank (looking downstream) of the Missouri River about 0.5 mile upstream from USGS streamflow gage 06486000, and approximately 5,000 feet downstream from the confluence with the Big Sioux River. The Missouri River, adjacent to the Sioux City alluvial well field, consists of the combined streamflows from the Missouri and the Big Sioux Rivers. The streamflows do not appear to be well mixed downstream from the confluence, and the streamflow directly adjacent to the well field could be predominately from the Big Sioux River. The U.S. Geological Survey measures streamflow on the Missouri River at Sioux City, Iowa (USGS streamflow gage 06486000). The riverbed of the Missouri River at Sioux City consists of a sequence of sands and gravels. The surface of the riverbed is undulatory, with continuously migrating riverbed forms, 5 to 8 feet in relief, of sand and gravel. Measurements of riverbed elevations from October 1, 2002, to September 30, 2003, showed an annual change of as much as 8 feet with the majority of the riverbed change closer to 5 feet. The largest change occurred near a wing dike on the Nebraska side of the Missouri River. On the Iowa side, the annual change was close to 5 feet. The results showed that channel fill occurred in the winter months and scour occurred during the summer months. Results of analyses of water samples collected at five locations across the Missouri River, near the municipal well field, were similar for most samples. Higher values of specific conductance and turbidity were recorded on the Iowa side of the Missouri River, the side from which the Big Sioux River enters upstream. Higher concentrations of chloride, ammonia nitrogen, nitrate nitrogen, and atrazine also were detected on the Iowa side of the Missouri River. Based on these results, there does not appear to be complete mixing of water from the Missouri and Big Sioux Rivers near the municipal well field.

Iowa↗
USGS2005

Snowmelt discharge characteristics Sierra Nevada, California

Alpine snow is an important water resource in California and the western U.S. Three major features of alpine snowmelt are the spring pulse (the first surge in snowmelt-driven river discharge in spring), maximum snowmelt discharge, and base flow (low river discharge supported by groundwater in fall). A long term data set of hydrologic measurements at 24 gage locations in 20 watersheds in the Sierra Nevada was investigated to relate patterns of snowmelt with stream discharge In wet years, the daily variations in snowmelt discharge at all the gage locations in the Sierra Nevada correlate strongly with the centrally located Merced River at Happy Isles, Yosemite National Park (i.e., in 1983, the mean of the 23 correlations was R= 0.93 + 0.09) ; in dry years, however, this correlation breaks down (i.e., in year 1977, R=0.72 + 0.24). A general trend towards earlier snowmelt was found and modeled using correlations with the timing of the spring pulse and the river discharge center of mass. For the 24 river and creek gage locations in this study, the spring pulse appeared to be a more sensitive measure of early snowmelt than the center of mass. The amplitude of maximum daily snowmelt discharge correlates strongly with initial snow water equivalent. Geologic factors, base rock permeability and soil-to-bedrock ratio, influence snowmelt flow pathways. Although both surface and ground water flows and water levels increase in wet years compared to dry years, the increase was greater for surface water in a watershed with relatively impermeable base rock than for surface water in a watershed with highly permeable base rock The relation was the opposite for base flow (ground water). The increase was greater for groundwater in a watershed with permeable rock compared to ground water in a watershed with impermeable rock. A similar, but weaker, surface/groundwater partitioning was observed in relatively impermeable granitic watersheds with differing soil-to-bedrock ratios. The increase in surface flow was greater in a watershed with a low, compared to a high, soil-to-bedrock ratio; whereas the increase in ground water flow was greater in a watershed with a high, compared to a low, soil-to-bedrock ratio. Transects that include long-term observations of shallow well-water depth and chemistry would complement traditional hydroclimate data and provide a more complete understanding of hydrologic controls of snowmelt.

California↗
USGS2008

Water Levels and Selected Water-Quality Conditions in the Mississippi River Valley Alluvial Aquifer in Eastern Arkansas, 2006

During the spring of 2006, the U.S. Geological Survey, in cooperation with the Arkansas Natural Resource Commission and the Arkansas Geological Survey, measured water levels in 707 wells completed in the Mississippi River Valley alluvial aquifer in eastern Arkansas. Ground-water levels are affected by ground-water withdrawals resulting in depressions. In 2006, the lowest water-level altitude was 76 feet above the National Geodetic Vertical Datum of 1929 in the center of Arkansas County. The highest water-level altitude was 289 feet above the National Geodetic Vertical Datum of 1929 in northeastern Clay County on the west side of Crowleys Ridge. Two large depressions in the potentiometric surface are located in Arkansas, Lonoke, and Prairie Counties and west of Crowleys Ridge in Craighead, Cross, Lee, Monroe, Poinsett, St. Francis, and Woodruff Counties. The elongated depression in Arkansas, Lonoke, and Prairie Counties has changed in areal extent or depth when compared to previous conditions of the aquifer. The area in Arkansas County at the southeastern half of the depression has not expanded horizontally during recent years, although the center of the depression has deepened. The area in Lonoke and Prairie Counties in the northwestern half of the depression has expanded horizontally in the deeper part of the depression. The 90-foot contour has expanded north and east in Lonoke County when compared with the 2004 potentiometric surface. Along the west side of Crowleys Ridge the 2006 potentiometric-surface map shows very little change in the area of this depression, although the deeper areas within the depression have expanded. A map showing the difference in water level was constructed using 645 differences in water-levels measured in 633 wells during 2002 and 2006. The difference in measured water levels from 2002 to 2006 ranged from -24.0 feet to 25.0 feet, with a mean of -2.0 feet. The largest decline of -24.0 feet occurred in Poinsett County and the largest rise of 25.0 feet occurred in Randolph County. Out of the 645 differences, 481 were declines (74.6 percent), 12 were no difference (values of 0.0 ft) (1.8 percent), and 152 were rises (23.6 percent). Long-term water-level trends were evaluated using hydrographs from 152 wells completed in the Mississippi River Valley alluvial aquifer for the period 1982 to 2006. The mean annual rise or decline in water level for the entire study area was -0.32 feet per year with a range of -1.28 to 0.77 feet per year. Independence and White Counties are the only counties with a mean annual rise from 1982 to 2006. Mean annual declines between -0.50 feet per year and 0.00 feet per year occurred in Arkansas, Ashley, Chicot, Clay, Craighead, Crittenden, Drew, Jefferson, Lee, Mississippi, Monroe, Phillips, Poinsett, Prairie, Pulaski, Randolph, and Woodruff Counties. Mean annual declines between -1.00 feet per year and -0.50 feet per year occurred in Cross, Desha, Greene, Jackson, Lincoln, Lonoke, and St. Francis Counties. The analysis of long-term water-level changes in Arkansas, Lonoke, and Prairie Counties shows the elongation of the depression in these three counties. Both Arkansas and Prairie Counties have two different rates of annual decline for the two hydrographs shown for each county. Water levels in the two wells near the Arkansas and White Rivers either have risen or declined at a slower rate than in the three wells in the center, northern, and western part of the depression. These rates of water-level change indicate that this depression is expanding in an elongated direction north and west into Lonoke and Prairie Counties. The depression west of Crowleys Ridge has five wells with hydrographs in or near the depression that can be used to characterize the rates of water-level change within the depression. Water samples were collected from 65 wells completed in the Mississippi River Valley alluvial aquifer and measured onsite for specific conductance and tempera

Scientific Investigations Report↗
USGS2000

Depth to bedrock in the upper San Pedro Valley, Cochise County, southeastern Arizona

The thickness, distribution, and character of alluvial sediments that were deposited in the structural subbasins of the upper San Pedro basin in southeastern Arizona during the late Cenozoic provide important constraints on ground-water availability of the area. Two sedimentary units are recognized; the Oligocene and Miocene Pantano(?) Formation and an unnamed upper Miocene through lower Pleistocene unit termed basin fill. The complete Bouguer gravity anomaly map shows that there are three major structural subbasins in the upper San Pedro basin north of the international border with Mexico. The Tombstone subbasin is north of Tombstone, and two more are located north and south of Sierra Vista, respectively. This report concentrates on the two subbasins north and south of Sierra Vista. The northern subbasin (termed the Huachuca City subbasin) extends from east of Huachuca City to northeast of Whetstone, and the southern subbasin (termed the Palominas subbasin) extends southward from a line between Nicksville and Hereford to the border. The locations and shapes of these subbasins, thickness of basin fill, and depth to bedrock were estimated using a procedure involving interpolation of (1) the density functions derived in this study, (2) stratigraphic data from water wells, and (3) a residual gravity anomaly grid obtained by subtracting the gravity effects of the bedrock ranges bordering the basin from the complete Bouguer gravity anomaly. This procedure indicates that the subbasins are shallow and contain significant thicknesses of the Pantano(?) Formation in addition to the overlying younger basin fill. The maximum depth to bedrock is about 1,700 m in the Palominas subbasin and 800m in the Huachuca City subbasin; the basin-fill unit occupies the upper 250-350 m in general with local thickenings exceeding 1,000 m in the Palominas subbasin. An east-west trending buried bedrock high beneath Fort Huachuca, Sierra Vista, and Charleston separates the subbasins. The depth to bedrock over this high is 200-500 m and the basin-fill unit ranges from 100 to 200 m thick there. A number of previously unrecognized faults were identified and the lengths of some of the known faults were extended based on reconnaissance geologic mapping, study of driller's logs, interpretation of aerial photographs and thematic mapper satellite images, and inspection of contoured gravity and aeromagnetic anomaly data. Many faults that segment the main San Pedro basin and shape the boundaries of the subbasins are apparently pre-existing faults that have been reactivated by Basin and Range extension.

Open-File Report↗
USGS2019

Assessing water quality from highway runoff at selected sites in North Carolina with the Stochastic Empirical Loading and Dilution Model (SELDM)

In 2015, the U.S. Geological Survey (USGS) entered into a cooperative agreement with the North Carolina Department of Transportation (NCDOT) to develop a North Carolina-enhanced variation of the national Stochastic Empirical Loading and Dilution Model (SELDM) with available North Carolina-specific streamflow and water-quality data and to demonstrate use of the model by documenting selected simulation scenarios. The USGS developed the national SELDM in cooperation with the Federal Highway Administration (FHWA) to provide the tools and techniques necessary for performing stormwater-quality simulations. SELDM uses a stochastic mass-balance approach to estimate combinations of flows, concentrations, and loads of stormwater constituents from the site of interest (often a highway catchment; nonhighway areas, such as a large impervious area at a shopping center complex, also can be used) and the basin upstream from the stormwater outfall to assess the risk for adverse effects of runoff. SELDM also can be used to simulate the effectiveness of volume reduction, hydrograph extension, and water-quality concentration reductions by stormwater best management practices (BMPs), which are designed to help mitigate the effects of runoff on receiving water bodies. Some of the statistical inputs needed for the North Carolina-enhanced SELDM were either calculated or augmented using local or regional data from North Carolina. Streamflow statistics used by SELDM were determined for 266 streamgages across North Carolina on the basis of data available through the 2015 water year. Recession ratio statistics used for triangular hydrographs were also developed for 30 streamgages across the State. The NCDOT identified previous research reports on highway-runoff and BMP studies in North Carolina for review of potential data addition to the national FHWA Highway-Runoff Database (HRDB). Following USGS review of these data, a total of 25,087 event mean concentration values and 1,140 storm events for 39 highway-runoff sites and 195 analytes were uploaded to the national HRDB from six North Carolina highway-runoff research reports and a recent USGS bridge deck runoff study. Using data for 27 streamgages in North Carolina, a total of 57 water-quality transport curves were developed for seven constituents for use in simulating water-quality conditions in the upstream basin. Performance data for three BMPs (bioretention, grass strip or swale, and wetland channel) from NCDOT research data were incorporated into the North Carolina-enhanced SELDM for volume-reduction statistics, including the effectiveness of treating four water-quality constituents (total suspended solids, total nitrogen, total phosphorus, nitrate plus nitrite) and turbidity. Simulations using the North Carolina-enhanced SELDM are presented for two hypothetical upstream basins in the Piedmont ecoregion and one hypothetical highway site to demonstrate how simulations can be used to provide risk-based information about potential effects of stormwater runoff on downstream water quality and the potential for mitigating those risks by using BMPs. The first group of simulations explores the stochastic variability in dilution factors (the ratio of the highway runoff to the total downstream stormflow) for a hypothetical Piedmont rural creek having drainage areas ranging from 1 to 100 square miles. The second group of simulations examines dilution factors based on variations in precipitation, streamflow, and recession ratios for two hypothetical Piedmont upstream basins (rural and urban) where the drainage area was held constant at 25 square miles. These simulations indicate the sensitivity of results to variations in each of the three variables. The third group of simulations examines the effects of varied concentrations in the upstream basin on water-quality conditions downstream from the highway crossing. Variations in upstream water-quality conditions for three constituents (suspended sediment concentration, total nitrogen, and total phosphorus) are based on water-quality transport curves selected from among the 57 curves developed as part of this study to represent low-, medium-, and high-concentration statistics. Simulations completed for this third group also examine the potential effects of grass swale and bioretention BMP treatment on total nitrogen and total phosphorus concentrations in highway runoff. The BMP performance data from the NCDOT research reports were applied in this group of simulations. The stochastic mass-balance approach used in SELDM analyses and simulations provides a strong tool for engineers and water-resource managers to use in exploring a wide range of possible hydrologic and water-quality inputs and their effects on downstream water quality. The results of this study can not only aid engineers and managers in planning for potential adverse effects of runoff at site-specific locations, they can also help the USGS and other Federal and State agencies with oversight responsibilities in stormwater-quality issues to continue gathering data on potential water-quality effects in receiving streams.

North Carolina↗
USGS2020

Assessment of dissolved-selenium concentrations and loads in the Lower Gunnison River Basin, Colorado, as part of the Selenium Management Program, 2011–17

The Gunnison Basin Selenium Management Program implemented a water-quality monitoring network in 2011 to measure concentrations of selenium in the lower Gunnison River Basin in Colorado. Selenium is a trace element that bioaccumulates in aquatic food chains. Selenium is essential for life, but elevated amounts can cause reproductive failure, deformities, and other harmful effects. The primary goal of the Selenium Management Program is to meet the State of Colorado water-quality standard of 4.6 micrograms per liter (µg/L) for dissolved selenium at the U.S. Geological Survey (USGS) streamflow-gaging station number 09152500—Gunnison River near Grand Junction, Colorado—herein referred to as “Whitewater.” The U.S. Geological Survey, in cooperation with the Bureau of Reclamation, has completed a review of dissolved-selenium data collected from the Selenium Management Program network during Water Year (WY) 2017 (October 1, 2016 through September 30, 2017) to further the understanding of the status and trends of selenium in the basin. This report presents the percentile values for selenium because regulatory agencies in Colorado make decisions based on the U.S. Environmental Protection Agency’s Clean Water Act section 303(d), which uses percentile values for concentrations. Also presented are dissolved-selenium loads at 14 sites in the lower Gunnison River Basin for WYs 2011–17. Annual dissolved-selenium loads were calculated for six sites with continuous U.S. Geological Survey streamflow-gaging stations. These six sites are referred to as “core” sites in this report. The remaining sites, which do not have streamflow-gaging stations, are referred to as “ancillary” sites in this report. During WY 2017, the loads calculated at the six core sites ranged from 306 pounds (lb) at Uncompahgre River at Colona to 12,600 lb at Whitewater, respectively. By using discrete water-quality samples and the associated discharge measurements, instantaneous loads were calculated for 14 sites in WYs 2011–17 where discrete water-quality sampling took place. Median instantaneous loads ranged from 0.52 pounds per day (lb/d) at Uncompahgre River at Colona to 35.7 lb/d at Whitewater. Mean instantaneous loads ranged from 0.63 lb/d at Cummings Gulch at mouth to 35.5 lb/d at Whitewater. Most tributary sites in the basin had a median instantaneous dissolved-selenium load of less than 20.0 lb/d. In general, dissolved-selenium loads at Gunnison River main-stem sites showed an increase from upstream to downstream. The State of Colorado’s water-quality standard for dissolved selenium of 4.6 µg/L was compared to the 85th percentiles for dissolved selenium at selected sites. Annual 85th percentiles for dissolved selenium were calculated by using estimated dissolved-selenium concentrations from linear regression models for the six core sites with U.S. Geological Survey streamflow-gaging stations. The 85th-percentile concentrations for WY 2017 based on this method ranged from 0.68 µg/L at Uncompahgre River at Colona to 140 µg/L at Loutzenhizer Arroyo at North River Road. The 85th percentiles for concentrations of dissolved selenium also were calculated from water-quality samples collected during WY 2017 from sites with sufficient data. The annual 85th-percentile concentrations based on the discrete samples ranged from 0.75 µg/L at Uncompahgre River at Colona to 106 µg/L at Loutzenhizer Arroyo at North River Road. An analysis was completed for Whitewater to determine if an upward or downward trend exists for dissolved-selenium loads during two time periods. The first time period included all data at Whitewater, whereas the second time period focused on more recent data. The trend analysis indicates a decrease from 22,200 to 12,600 lb, which is a 43.1 percent (9,600 lb) reduction during the time period WY 1986 through WY 2017. The trend analysis for the annual dissolved-selenium load for WY 1995 through WY 2017 indicates a decrease of 6,600 lb per year, or 35.5 percent. An evaluation of laboratory bias was completed for selenium data which was used in the trend analysis. Findings indicated a potential positive bias of approximately 12 percent may exist in the data from October 2005 through August 2015.

Colorado↗
USGS2008

Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona— 2006-07

The N aquifer is the major source of water in the 5,400 square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use and the needs of a growing population. Precipitation in the Black Mesa area is typically about 6 to 14 inches per year. The water-monitoring program in the Black Mesa area began in 1971 and is designed to provide information about the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected for the monitoring program in the Black Mesa area from January 2006 to September 2007. The monitoring program includes measurements of (1) ground-water withdrawals, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, and (5) ground-water chemistry. Periodic testing of ground-water withdrawal meters is completed every 4 to 5 years. The Navajo Tribal Utility Authority (NTUA) yearly totals for the ground-water metered withdrawal data were unavailable in 2006 due to an up-grade within the NTUA computer network. Because NTUA data is often combined with Bureau of Indian Affairs data for the total withdrawals in a well system, withdrawals will not be published in this year's annual report. From 2006 to 2007, annually measured water levels in the Black Mesa area declined in 3 of 11 wells measured in the unconfined areas of the N aquifer, and the median change was 0.0 feet. Measurements indicated that water levels declined in 8 of 17 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was 0.2 feet. From the prestress period (prior to 1965) to 2007, the median water-level change for 30 wells was -11.1 feet. Median water-level changes were 2.9 feet for 11 wells measured in the unconfined areas and -40.2 feet for 19 wells measured in the confined area. Spring flow was measured once in 2006 and once in 2007 at Moenkopi School Spring. Flow decreased by 18.9 percent at Moenkopi School Spring. During the period of record, flow fluctuated, and a decreasing trend was apparent. Continuous records of surface-water discharge in the Black Mesa area have been collected from streamflow gages at the following sites: Moenkopi Wash at Moenkopi (1976 to 2006), Dinnebito Wash near Sand Springs (1993 to 2006), Polacca Wash near Second Mesa (1994 to 2006), and Pasture Canyon Springs (August 2004 to December 2006). Median flows during November, December, January, and February of each water year were used as an index of the amount of ground-water discharge to the above named sites. For the period of record at each streamflow-gaging station, the median winter flows have generally remained even, showing neither a significant increase nor decrease in flows. There is not a long enough period of record for Pasture Canyon Spring for a trend to be apparent. In 2007, water samples were collected from 1 well and 1 spring in the Black Mesa area and were analyzed for selected chemical constituents. Concentrations of dissolved solids, chloride, and sulfate have varied at Peabody well 5 for the period of record, and there is an apparent increasing trend. Dissolved-solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 12 years of record.

Arizona↗
USGS1972

A geochemical study of the Rio Pantanos area, Department of Antioquia, Colombia preliminary report

Geochemical sampling in the Western Cordillera has delineated an 18 km 2 area anomalous in copper, molybdenum, and silver. Highly anomalous metal contents are found in stream sediment, soil, and outcrop samples collected within this area. The area is underlain by intrusive granodiorite to quartz diorite that has porphyritic and granitoid phases. Most of the outcrop samples contain disseminated pyrite, chalcopyrite, and bornite. A geochemical reconnaissance sampling program in the Western Cordillera, formulated by Andros Jimeno V., Director, Instituto National de Investigaciones Geologico-Mineras (INGEOMINAS), and Earl M. Irving, U. S. Geological Survey (USGS) Chief of Party in Colombia, was carried out from 1969 to 1971 by geologists of the INGEOMINAS office in Medellin. This work was part of a cooperative program of INGEOMINAS and the USGS sponsored by the Government of Colombia and the Agency for International Development, U. S. Department of State. Seventeen generally east-trending traverses were completed across the Western Cordillera. These traverses, generally paralleling major drainages, cross the range at intervals of 10 to 30 km.

Open-File Report↗
USGS2003

USGS National Assessment of Oil and Gas Online (NOGA Online)

The Central Energy Resources Team (CERT) of the U.S. Geological Survey is providing results of the USGS National Assessment of Oil and Gas online (NOGA Online). In addition to providing resource estimates and geologic reports, NOGA Online includes an internet map application that allows interactive viewing and analysis of assessment data and results. CERT is in the process of reassessing domestic oil and natural gas resources in a series of priority basins in the United States using a Total Petroleum System (TPS) approach where the assessment unit is the basic appraisal unit (rather than the oil and gas play used in the 1995 study). Assessments of undiscovered oil and gas resources in five such priority provinces were recently completed to meet the requirements of the Energy Policy and Conservation Act of 2000 (EPCA 2000). New assessment results are made available at this site on an ongoing basis.

Fact Sheet↗
USGS2024

Distribution, abundance, and breeding activities of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2020 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton (MCBCP, or Base). Surveys for the Least Bell's Vireo were conducted at MCBCP, California, between April 1 and July 10, 2020. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed 3–4 times. We detected 669 territorial male vireos and 16 transient vireos in core survey areas. An additional 156 territorial male vireos were detected in non-core survey areas. Territorial vireos were detected on all 10 drainages/sites surveyed (core and non-core areas). Of the vireo territories in core areas, 88 percent were on the 4 most populated drainages, with the Santa Margarita River containing 69 percent of all territories. In core areas, 79 percent of male vireos were confirmed as paired; 83 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP (669) increased 39 percent from 2019 to 2020. The number of territories in all core survey area drainages increased by one or more between 2019 and 2020. The substantial increase in vireo numbers on MCBCP (39 percent) was consistent with population changes in surrounding areas, including the lower San Luis Rey River (26 percent), Marine Corps Air Station, Camp Pendleton (58 percent), and the middle San Luis Rey River (7 percent). Most core-area vireo territories (69 percent of males) occurred in willow ( Salix spp.) riparian habitat. An additional 4 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Eighteen percent of territories were found in riparian scrub dominated by mule fat ( Baccharis salicifolia ) or sandbar willow ( S. exigua ). Upland scrub was used by 7 percent or fewer vireos; 1 percent of territories occurred in non-native vegetation, and less than 1 percent of vireo territories occurred in habitat co-dominated by coast live oak ( Quercus agrifolia ) and sycamore. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River. The artificial seep pumped water to the surface from March through August each year during daylight hours and was designed to increase the amount of surface water present to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ; flycatcher) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited the seep and proposed seep areas within the past several years. Therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents preliminary analyses of vireo and vegetation response to the existing artificial seep. We sampled vegetation in the Seep site and three Reference sites to determine the effects of a new water diversion dam that was completed in 2019 and a surface water enhancement seep pump installed along the Santa Margarita River. We found minor differences in non-native vegetation cover between Reference sites and the Seep site. However, soil moisture was higher at the Reference sites compared to the Seep site. The effect of the seep pump may have been masked by high precipitation in the bio-year (July 1‒June 30) before 2020, limited time for the water diversion to have an effect, well-draining soil, and the non-operation of two to three of the six seep outlets. We color banded and resighted color banded Least Bell’s Vireos to evaluate adult site fidelity, between-year movement, and the effect of surface water enhancement on vireo site fidelity and between-year movement. We banded 146 Least Bell's Vireos for the first time during the 2020 season. Birds banded included 27 adult vireos and 119 juvenile vireos. All adult vireos were banded with unique color combinations. The juvenile vireos (all nestlings) were banded with a single gold numbered federal band on the left leg. We resighted and identified 85 Least Bell's Vireos banded before the 2020 breeding season on Base in 2020. Of the 85, 13 vireos were originally banded on the San Luis Rey River, 2 were banded in Baja California Sur, 1 was banded at Marine Corps Air Station, Camp Pendleton, and the remaining birds were banded at MCBCP. Adult birds of known age ranged from 1 to 8 years old. Most returning adult vireos showed strong between-year site fidelity. Of the adults present in 2019 and 2020, 74 percent, (79 percent of males; 40 percent of females) returned to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.3 plus or minus (±) 0.8 kilometer (km). The average movement of first-year vireos detected in 2020 that fledged from a known nest on MCBCP in 2019 was 4.7±7.0 km. One first-year vireo that originated at MCBCP moved off Base and was detected at Murrieta Creek, 23.0 km from his natal territory. We monitored Least Bell's Vireo pairs to evaluate the effects of surface water enhancement on nest success and breeding productivity. Vireos were monitored at one Seep site and three Reference sites. Base personnel plan to install a second seep pump at one of the Reference sites in the future, at which time the status of the monitoring site will change from Reference to Seep. Nesting activity was monitored between March 31 and July 28 in 52 territories within the Seep and Reference sites (12 at the Seep site and 40 at Reference sites). All territories were occupied by pairs, and all but one territory was fully monitored, meaning all nesting attempts were monitored at these territories. One vireo territory within a Reference site was partially monitored. During the monitoring period, 94 nests (25 in the Seep site and 69 in Reference sites) were monitored. Breeding productivity was similar at the Seep site and Reference sites (3.7 and 2.9 young per pair, respectively), with 75 percent of Seep pairs and 79 percent of Reference pairs successfully fledging at least 1 young in 2020. Compared to Reference sites, the Seep site had a higher proportion of all eggs that hatched and also a higher proportion of nests with eggs that hatched. Conversely, a lower proportion of hatchlings and nests that had hatchlings fledged at the Seep site than at Reference sites. According to the best model, nest survival in 2020 was not affected by treatment (Seep versus Reference), although the second best model that included treatment was also well supported. Completed nests at the Seep site were likely to be as successful as nests at Reference sites in 2020 (57 percent and 59 percent, respectively). Predation was believed to be the primary source of nest failure at both sites. Predation accounted for 90 percent and 73 percent of nest failures at Seep and Reference sites, respectively. Failure of the remaining eight nests was attributed to the collapse of the nesting substrate, exposure to rain and flooding, and other unknown reasons. Fourteen plant species were used as hosts for vireo nests in 2020. In 2020, we found that at the Seep site, successful nests were placed in taller host plants and further from the edge of host plants (closer to the center) than unsuccessful nests. We found no difference in nest placement between the Seep site and the Reference sites.

California↗
USGS2006

Cross-Sectional Data for Selected Reaches of the Chattahoochee River within the Chattahoochee River National Recreation Area, Georgia, 2004

This report presents hydrologic data for selected reaches of the Chattahoochee River within the Chattahoochee River National Recreation Area (CRNRA). Data about transect location, width, depth, and velocity of flow for selected reaches of the river are presented in tabular form. The tables contain measurements collected from shoal and run habitats identified as critical sites for the CRNRA. In shoal habitats, measurements were collected while wading using a digital flowmeter and laser range finder. In run habitats, measurements were collected using acoustic Doppler current profiling. Fifty-three transects were established in six reaches throughout the CRNRA; 24 in shoal habitat, 26 in run habitat, and 3 in pool habitat. Illustrations in this report contain information about study area location, hydrology, transect locations, and cross-sectional information. A study area location figure is followed by figures identifying locations of transects within each individual reach. Cross-sectional information is presented for each transect, by reach, in a series of graphs. The data presented herein can be used to complete preliminary habitat assessments for the Chattahoochee River within the CRNRA. These preliminary assessments can be used to identify reaches of concern for future impacts associated with continual development in the Metropolitan Atlanta area and potential water allocation agreements between Georgia, Florida, and Alabama.

Georgia↗
USGS2021

Least Bell's Vireos and Southwestern Willow Flycatchers at the San Luis Rey flood risk management project area in San Diego County, California—Breeding activities and habitat use—2020 annual report

Executive Summary Surveys and monitoring for the endangered Least Bell’s Vireo ( Vireo bellii pusillus ; vireo) were done at the San Luis Rey Flood Risk Management Project Area (Project Area) in the city of Oceanside, San Diego County, California, between March 31 and July 20, 2020. We completed four protocol surveys during the breeding season, supplemented by weekly territory monitoring visits. We identified a total of 161 territorial male vireos; 145 were confirmed as paired and 4 were confirmed as single males. For the remaining 12 territories, we were unable to confirm pair status. Three transient vireos were detected in 2020. The vireo population in the Project Area increased by 26 percent from 2019 to 2020. Vireo populations increased across San Diego County, with a 39-percent increase documented at Marine Corps Base Camp Pendleton (MCBCP); a 58-percent increase at Marine Corps Air Station; a 78-percent increase on the Otay River; and a 7-percent increase in the population on the middle San Luis Rey River. We used an index of treatment (Treatment Index) to evaluate the impact of on-going vegetation clearing on the Project Area vireo population. The Treatment Index measures the cumulative effect of vegetation treatment within a territory (since 2005) by using the percent area treated weighted by the number of years since treatment. We found that the Treatment Index for unoccupied habitat was more than five times that of occupied habitat, indicating that vireos selected less disturbed habitat in which to settle. We monitored vireo nests at three general site types: (1) within the flood channel where exotic and native vegetation removal has occurred regularly (Channel), (2) three sites next to the flood channel where limited exotic and native vegetation removal has occurred (Off-channel), and (3) three sites that have been actively restored by planting native vegetation (Restoration). Nesting activity was monitored in 100 territories, 4 of which were occupied by single males. Hatching success was higher in the Channel relative to the Off-channel. We found no other differences between Channel, Off-channel, and Restoration nests in terms of clutch size or fledging success. There also was no difference in measures of productivity per pair between Channel, Off-channel, Restoration, and Mixed territories (territories that were classified as one site type but nesting occurred in another site type, or where multiple site types were used for nesting). Overall, breeding success and productivity were lower in 2020 than in 2019, with 69 percent of pairs fledgling at least one young and pairs fledging an average of 2.1±1.7 young. To investigate whether the cumulative years of treatment had an impact on vireo reproductive effort, we looked at the effects of the Treatment Index on reproductive parameters. Results from generalized linear models indicated that treatment did not have an effect on vireo nesting effort or the number of vireo fledglings per pair produced in 2020. Similarly, our analysis of nest survival for 2020 revealed no effect of Treatment Index on daily survival rate. Analysis of vegetation data collected at vireo nests from 2006 to 2020 revealed that vegetation at 1–2 meters (m) from the ground was the most important predictor of daily survival rate. There were differences in nest-placement characteristics among site types and successful/unsuccessful nests. Channel nests were placed higher in the vegetation than Off-channel or Restoration nests. Host plant height, distance to edge of host plant, and distance to edge of vegetation clump were greater at Channel sites compared with Off-channel sites, but were not different from Restoration sites. Within sites, we found only one difference between successful and unsuccessful nests. At Off-channel sites, successful nests were placed higher in the vegetation than unsuccessful nests. Red/arroyo willow ( Salix laevigata or Salix lasiolepis ) and mule fat ( Baccharis salicifolia ) were the species most commonly selected for nesting by vireos in all 3 site types. Vireos used a wider variety of species for nesting in Channel and Off-channel sites (7 and 10 species, respectively) compared to Restoration sites (3 species). Ninety-three vireos banded before the 2020 breeding season were resighted and identified at the Project Area in 2020, all of which were originally banded at the Project Area. Adult birds of known age ranged from 1 to 9 years old. A total of 171 vireos were newly banded in 2020. Twenty-eight adult vireos were banded with a unique color combination, and 143 nestlings were banded with a single dark blue numbered federal band on the left leg. Between 2006 and 2020, survivorship of males (67±10 percent) was consistently higher than females (59±11 percent). First-year birds from 2006 to 2020 had an average over-winter survivorship of 17±5 percent. First-year dispersal in 2020 averaged 2.9±2.9 kilometers (km), with the longest dispersal (13.5 km) by a female that was recaptured at Las Flores Creek, MCBCP. From 2007 to 2012, most returning first-year vireos returned to the Project Area, whereas from 2013 to 2017, the majority of returning birds dispersed to areas outside of the Project Area. In 2018, the trend shifted, and most first-year vireos returned to the Project area. This trend continued in 2020 with most first-year vireos returning to the Project Area; 77 percent of all re-encountered first-year birds returned to the Project Area and 23 percent dispersed to areas outside of the Project Area (upstream to the middle San Luis Rey River and to drainages on MCBCP). Most of the returning adult male vireos showed strong between-year site fidelity to their previous territories. Eighty percent of males (45/56) occupied a territory in 2020 that they had defended in 2019 (within 100 m). Thirty-three percent of females (2/6) detected in 2020 returned to a territory that they occupied in 2019. The average between-year movement for returning adult vireos was 0.1±0.5 km. We completed four protocol surveys for the endangered Southwestern Willow Fycatcher ( Empidonax traillii extimus ; flycatcher) at the Project Area between May 20 and July 20, 2020. No Willow Flycatchers were detected in the Project Area in 2020. A total of 46 vegetation transects (526 points) were sampled at the San Luis Rey Flood Risk Management Project Area in 2020. Seventy-one percent (376/526) of points were in the Channel and 22 percent (115/526) were at Upper Pond. The remaining 7 percent (35/526) were at the Whelan Restoration site. Foliage cover below 1 m was higher at the Channel points compared to Upper Pond and Whelan Restoration. Higher foliage cover in the Channel was attributed to the higher herbaceous component. However, foliage cover from 1 to 3 m was higher at the Whelan Restoration site compared to both Upper Pond and the Channel. Average canopy height was similar at all three site types and was 4.4 m or less. From 2006 to 2020, total foliage cover declined above 1 m in the Channel, from 4 to 5 m at Upper Pond, and above 8 m at Whelan Restoration. Within the Channel, the steepest declines occurred between 2009 and 2013 and between 2014 and 2016. Since 2016, we observed an increase in percent foliage between 0 and 2 m within the Channel, but for other height classes, percent cover remained below levels detected before 2009. Changes in cover at Upper Pond and Whelan Restoration appeared to be driven by the loss of tall tree cover. The vegetation mowing and treatment activities, in combination with lack of precipitation (especially between 2012 and 2016), may have contributed to the decline in foliage cover observed from 2006 to 2020. We sampled vegetation at 49 vireo nests and 49 random plots (“territory” plots) within territories in the Channel and Upper Pond following the 2020 breeding season. Vireos in the Channel selected territories with significantly more foliage cover above 2 m but less cover below 1 m relative to the available habitat. In contrast, Channel vireos selected nest sites within their territories with lower foliage cover above 3 m and were non-selective with regard to cover below 2 m. Vireos at Upper Pond generally were less selective with regard to territory and nest sites but tended to select territories with more foliage cover from 1 to 2 m and above 8 m, and they selected nest sites within their territories with greater foliage cover from 0 to 1 m.

California↗
USGS2020

Earthquakes, did you feel it?

The US Geological Survey (USGS) “Did You Feel It?” ® (DYFI) system is an automated system for rapidly collecting macroseismic intensity data from Internet users’ shaking and damage reports and generating intensity maps immediately following earthquakes. Although the collection and assignment of DYFI-based Macroseismic Intensity (MI) data depart from traditional assignments, they are made more quickly, provide more complete coverage at higher spatial resolution, offer citizen input and interaction, and allow data collection at rates and quantities that were not previously possible. These aspects of Internet-based data collection, in turn, allow for data analyses, graphics, and ways to communicate with the public, opportunities that were not feasible with traditional data-collection approaches.

Book chapter↗
USGS2014

Golden alga presence and abundance are inversely related to salinity in a high-salinity river ecosystem, Pecos River, USA

Prymnesium parvum (golden alga, GA) is a toxigenic harmful alga native to marine ecosystems that has also affected brackish inland waters. The first toxic bloom of GA in the western hemisphere occurred in the Pecos River, one of the saltiest rivers in North America. Environmental factors (water quality) associated with GA occurrence in this basin, however, have not been examined. Water quality and GA presence and abundance were determined at eight sites in the Pecos River basin with or without prior history of toxic blooms. Sampling was conducted monthly from January 2012 to July 2013. Specific conductance (salinity) varied spatiotemporally between 4408 and 73,786 mS/cm. Results of graphical, principal component (PCA), and zero-inflated Poisson (ZIP) regression analyses indicated that the incidence and abundance of GA are reduced as salinity increases spatiotemporally. LOWESS regression and correlation analyses of archived data for specific conductance and GA abundance at one of the study sites retrospectively confirmed the negative association between these variables. Results of PCA also suggested that at <15,000 mS/cm, GA was present at a relatively wide range of nutrient (nitrogen and phosphorus) concentrations whereas at higher salinity, GA was observed only at mid-to-high nutrient levels. Generally consistent with earlier studies, results of ZIP regression indicated that GA presence is positively associated with organic phosphorus and in samples where GA is present, GA abundance is positively associated with organic nitrogen and negatively associated with inorganic nitrogen. This is the first report of an inverse relation between salinity and GA presence and abundance in riverine waters and of interaction effects of salinity and nutrients in the field. These observations contribute to a more complete understanding of environmental conditions that influence GA distribution in inland waters.

New Mexico, Texas↗
USGS2026

Distribution and abundance of Least Bell’s Vireos ( Vireo bellii pusillus ) and Southwestern Willow Flycatchers ( Empidonax traillii extimus ) at the Mojave River Dam, San Bernardino County, California—2025 Data Summary

Executive Summary We surveyed for Least Bell’s Vireos ( Vireo bellii pusillus ; vireo) and Southwestern Willow Flycatchers ( Empidonax traillii extimus ; flycatcher) at the Mojave River Dam study area near Hesperia, California, in 2025. Four vireo surveys were completed between April 23 and June 26, 2025, and three flycatcher surveys were completed between May 16 and June 26, 2025. We detected two territorial male vireos, both of which were paired, and one transient vireo. No juvenile vireos were observed during surveys. Vireos were reported in two habitat types: riparian scrub dominated by narrowleaf willow ( Salix exigua ) or mule fat ( Baccharis salicifolia ) and willow-cottonwood dominated by red or arroyo willow ( Salix laevigata or lasiolepis ). One transient willow flycatcher of unknown subspecies was observed in willow-cottonwood habitat dominated by Fremont cottonwood ( Populus fremontii ).

California↗