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At least 1,657 records · Page 92Linked to original sources
USGS2021

Groundwater development leads to decreasing arsenic concentrations in the San Joaquin Valley, California

In the San Joaquin Valley (SJV), California, about 10% of drinking water wells since 2010 had arsenic concentrations above the US maximum contaminant level of 10 μg/L. High concentrations of arsenic are often associated with high pH (greater than 7.8) or reduced geochemical conditions. Although most wells have low arsenic (<3 μg/L) and do not have changing arsenic concentrations, this study found that most wells with concentrations above 10 μg/L had arsenic trends. Overall, about 24% of wells had time-series trends since 2010 and 59% had paired-sample trends since 2000. Most wells had decreasing arsenic trends, even in wells with higher arsenic concentrations. These wells often had co-detections of increasing nitrate and sulfate trends that reflect oxic groundwater likely derived from agricultural recharge. Wells with increasing arsenic trends were deeper or located in the valley trough where aquifer materials are more fine-grained and where reducing conditions favor arsenic mobility. Wells with arsenic trends also tend to be clustered near areas of higher well density. Groundwater pumping in these areas has likely increased the contribution of younger, more oxic groundwater in wells with declining arsenic or, less frequently, increased the contribution of higher pH or reduced groundwater in wells with rising arsenic. Projections of arsenic trends indicate that 37 wells with high arsenic presently will be below 10 μg/L in ten years. Unfortunately, these improvements will be largely offset by 31 wells that are expected to increase above 10 μg/L in addition to expected rises in nitrate in wells where arsenic decreased. This study shows how human-altered flow systems can impact the natural geochemical character of water in both beneficial and deleterious ways.

California↗
USGS2015

Long term changes in trout numbers following channel reconstruction, instream wood placement, and livestock removal from a spring creek in the Blackfoot Basin, Montana

To restore habitat for wild trout, Kleinschmidt Creek, a low-gradient, groundwater-dominated stream in the Blackfoot Basin, Montana, was reconstructed using natural channel design principles. Reconstruction increased stream sinuosity from a ratio of 1.1 to 1.6, decreased mean channel width from 14.5 to 2.8 m, and increased sediment transport capacity to reduce accumulations of fine instream sediment. To further improve trout habitat, coarse woody debris (CWD) was variably placed within the new channel and livestock were excluded to promote the vegetative recovery of the riparian area. To evaluate the response of wild trout (92% Brown Trout Salmo trutta ) to channel restoration, the abundance (number of trout per linear meter) and biomass (g/linear m) of age 1+ trout were monitored for 15 years (1998–2012) in a reach with low density CWD (1.3 stems/100 m) and compared with regional (reference) trends. Posttreatment (2002–2012) trout numbers in the low-density CWD reach were also compared with those in a reach with high-density CWD (18.2 stems/100 m). Long-term trends for the reference reaches showed a significant negative trend in trout abundance and no significant trend for biomass. Long-term trends for the low-density CWD reach showed a significant positive trend in abundance, as well as a significant trend in biomass. Trout abundance and biomass increased over the posttreatment period in the low-density CWD reach. However, in the high density CWD reach, while posttreatment abundance increased significantly, there was no significant trend in biomass. These results demonstrated that channel restoration increased wild trout populations in a deep, narrow, vegetated stream and that instream wood provided primarily short-term benefits during the early phase of habitat recovery.

Montana↗
USGS2016

Elevated bladder cancer in northern New England: The role of drinking water and arsenic

Background: Bladder cancer mortality rates have been elevated in northern New England for at least five decades. Incidence rates in Maine, New Hampshire, and Vermont are about 20% higher than the United States overall. We explored reasons for this excess, focusing on arsenic in drinking water from private wells, which are particularly prevalent in the region. Methods: In a population-based case-control study in these three states, 1213 bladder cancer case patients and 1418 control subjects provided information on suspected risk factors. Log transformed arsenic concentrations were estimated by linear regression based on measurements in water samples from current and past homes. All statistical tests were two-sided. Results: Bladder cancer risk increased with increasing water intake ( P trend = .003). This trend was statistically significant among participants with a history of private well use ( P trend = .01). Among private well users, this trend was apparent if well water was derived exclusively from shallow dug wells (which are vulnerable to contamination from manmade sources, P trend = .002) but not if well water was supplied only by deeper drilled wells ( P trend = .48). If dug wells were used pre-1960, when arsenical pesticides were widely used in the region, heavier water consumers (>2.2 L/day) had double the risk of light users (<1.1 L/day, P trend = .01). Among all participants, cumulative arsenic exposure from all water sources, lagged 40 years, yielded a positive risk gradient ( P trend = .004); among the highest-exposed participants (97.5th percentile), risk was twice that of the lowest-exposure quartile (odds ratio = 2.24, 95% confidence interval = 1.29 to 3.89). Conclusions: Our findings support an association between low-to-moderate levels of arsenic in drinking water and bladder cancer risk in New England. In addition, historical consumption of water from private wells, particularly dug wells in an era when arsenical pesticides were widely used, was associated with increased bladder cancer risk and may have contributed to the New England excess.

New England↗
USGS2020

Geology of the Trout Rock caves (Hamilton Cave, Trout Cave, New Trout Cave) in Pendleton County, West Virginia (USA), and implications regarding the origin of maze caves

The Trout Rock caves (Hamilton Cave, Trout Cave, New Trout Cave) are located in a hill named Cave Knob that overlooks the South Branch of the Potomac River in Pendleton County, West Virginia (U.S.A). The geologic structure of this hill is a northeasttrending anticline, and the caves are located at different elevations primarily along the contact between the Devonian New Creek Limestone (Helderberg Group) and the overlying Devonian Corriganville Limestone (Helderberg Group). The entrance to New Trout Cave (Stop 1) is located on the east flank of Cave Knob anticline at an elevation of 585 m (1,920 ft) relative to sea level, or 39 m (128 ft) above the modern river. Much of the cave consists of passages that extend to the northeast along strike, and many of these passages have developed along primary joints that trend N40E or secondary joints that trend N40W. Sediments in New Trout Cave include mud and sand (some of which was mined for nitrate during the American Civil War), as well as large boulders in the front part of the cave. Gypsum crusts are present in a maze section of the cave ~213 to 305 m (700 to 1,000 ft) from the cave entrance. Excavations in New Trout Cave have produced vertebrate fossils of Rancholabrean age, ~300,000 to 10,000 years Before Present (BP). The entrance to Trout Cave (Stop 2) is located on the east flank of Cave Knob anticline ~100 m (328 ft) northwest of the New Trout Cave entrance at an elevation of 622 m (2,040 ft) relative to sea level, or 76 m (249 ft) above the modern river. Much of the cave consists of passages that extend to the northeast along strike, although a small area of network maze passages is present in the western portion of Trout Cave that is closest to Hamilton Cave. Many of the passages of Trout Cave have developed along primary joints that trend N40E or secondary joints that trend N40W. Sediments in Trout Cave include mud (also mined for nitrate during the American Civil War), as well as large boulders in the front part of the cave. Excavations in the upper levels of Trout Cave have produced vertebrate fossils of Rancholabrean age (~300,000 to 10,000 years BP), whereas excavations in the lower levels of the cave have produced vertebrate fossils of Irvingtonian age (~1,810,000 to 300,000 years BP). The entrance to Hamilton Cave (Stop 3) is located along the axis of Cave Knob anticline ~165 m (540 ft) northwest of the Trout Cave entrance at an elevation of 640 m (2,100 ft) relative to sea level, or 94 m (308 ft) above the modern river. The front (upper) part of Hamilton Cave has a classic network maze pattern that is an angular grid of relatively horizontal passages, most of which follow vertical or near-vertical primary joints that trend N40W and N50W and secondary joints that trend N60W and N80E. This part of the cave lies along the axis of Cave Knob anticline. In contrast, the passages in the back (lower) part of Hamilton Cave lie along the west flank of Cave Knob anticline at ~58 to 85 m (190 to 279 ft) above the modern river. These passages do not display a classic maze pattern, and instead they may be divided into the following two categories: (1) longer northeast-trending passages that are relatively horizontal and follow the strike of the beds; and (2) shorter northwest-trending passages that descend steeply to the west and follow the dip of the beds. Sediments in Hamilton Cave include mud (which was apparently not mined for nitrate during the American Civil War), as well as large boulders in the front part of the cave. Gypsum crusts are present along passage walls of the New Creek Limestone from the Slab Room to the Airblower. Excavations in the front part of Hamilton Cave (maze section) have produced vertebrate fossils of Irvingtonian age (~1,810,000 to 300,000 years BP). The network maze portions of Hamilton Cave are interpreted as having developed at or near the water table where water did not have a free surface in contact with air and where the following conditions were present: (1) Location on or near the axis of an anticline (the location of the greatest amount of flexure); (2) Abundant vertical or near vertical joints, which are favored by location in the area of greatest flexure and by a lithologic unit (chert-rich limestone) that is more likely to experience brittle rather than ductile deformation; (3) Widening of joints to enhance ease of water infiltration, favored by location in area of greatest amount of flexure; and (4) Dissolution along nearly all major joints to produce cave passages of approximately the same size (which would most likely occur via water without a free surface in contact with air). The cave passages that are located along anticline axes and along strike at the New Creek-Corriganville contact are interpreted as having formed initially during times of base level stillstand at or near the water table where water did not have a free surface in contact with air and where the water flowed along the hydraulic gradient at gentle slopes. Under such conditions, dissolution occurred in all directions to produce cave passages with relatively linear wall morphologies. In the lower portions of some of the along-strike passages, the cave walls have a more sinuous (meandering) morphology, which is interpreted as having formed during subsequent initial base level fall as cave development continued under vadose conditions where the water had a free surface in contact with air, and where water flow was governed primarily by gravitational processes. Steeply inclined cave passages that are located along dip at the New Creek-Corriganville contact are interpreted as having formed during subsequent true vadose conditions (after base level fall). This chronology of base level stasis (with cave development in the phreatic zone a short distance below top of water table) followed by base level fall (with cave development in the vadose or epiphreatic zone) has repeated multiple times at Cave Knob during the past ~4 to 3 million years, resulting in multiple cave passages at different elevations, with different passage morphologies, and at different passage locations with respect to strike and dip.

West Virginia↗
USGS2004

Changes in the proportion of precipitation occurring as snow in New England (1949-2000)

The ratio of snow to total precipitation (S/P) is a hydrologic indicator that is sensitive to climate variability and can be used to detect and monitor hydrologic responses to climatic change. Changes in S/P ratio over time could influence the magnitude and timing of spring runoff and recession to summer baseflow. The S/P ratio for 21 U.S. Historical Climatology Network sites in New England was examined. Eleven out of twenty-one sites in New England had significant decreasing annual S/P ratios from 1949 to 2000. Annual trends in S/P are predominantly a result of decreasing snowfall, and to a lesser extent, increasing rainfall. The most consistent trends were in northernmost New England where all four sites had decreasing ratios, and in the coastal and near-coastal areas where five out of eight sites had significantly decreasing ratios. The four sites in northernmost New England, which had the strongest and most coherent trends, showed an average decrease in annual S/P ratio from about 0.30 in 1949 to 0.23 in 2000. Trends in winter S/P ratio were less geographically consistent. Seven out of 21 sites had significantly decreasing winter S/P ratios. Most northern New England and coastal to near-coastal sites had statistically significant trends (p < 0.05) or weak, but not significant trends (p < 0.2). When trends in S/P were analyzed on a monthly basis for the northernmost sites, it was evident that decreasing S/P trends were significant for March and December only. Significant correlations were observed between winter S/P ratios in northern New England and the timing of spring runoff, the North Atlantic Oscillation (NAO) index, and the Pacific-North American (PNA) index. Significant correlations were observed between winter S/P ratios averaged for all of New England and the NAO and PNA.

Journal of Climate↗
USGS2007

Strategic Plan for the North American Breeding Bird Survey: 2006-2010

Executive Summary The mission of the North American Breeding Bird Survey (BBS) is to provide scientifically credible measures of the status and trends of North American bird populations at continental and regional scales to inform biologically sound conservation and management actions. Determining population trends, relative abundance, and distributions of North American avifauna is critical for identifying conservation priorities, determining appropriate conservation actions, and evaluating those actions. The BBS program, jointly coordinated by the U.S. Geological Survey and Environment Canada’s Canadian Wildlife Service, provides the U.S. and Canadian Federal governments, state and provincial agencies, other conservation practitioners, and the general public with science-based avian population trend estimates and other information for regional and national species’ population assessments. Despite the demonstrated value of the BBS for furthering avian conservation across North America, its importance is often underappreciated, and it is underfunded compared with many other government-supported programs that report on status of the environment. Today, BBS resources, adjusted for inflation, are below the amount allocated in the 1970s and are still only sufficient to support two biologists. Yet the number of routes, participants, data, and data requests has quadrupled. Data and information management and delivery requirements and security concerns, non-existent in 1966, impose further demands on BBS resources. In addition, the Mexican expansion of the BBS offers new hope for a truly continental approach to avian conservation, but also brings additional challenges. Meeting the goals of this plan will take cooperation among myriad stakeholders; yet, even with collaboration, most objectives of this plan will be unattainable if BBS program support is not increased. The BBS developed this strategic plan to help set priorities and identify resources required for the program to continue to meet the evolving needs of the conservation community for information on bird population change. By setting clear goals, strategies, and measures of success, this plan provides a cohesive framework and vision for maintenance and development of the BBS. The plan identifies two major goals for the BBS, with a number of strategies and objectives to achieve these goals. Over the next 5 years, progress made in addressing each long-term goal and its associated 5-year strategies and objectives will gage the plan’s success. Specific actions, projected outcomes, and measures of success related to accomplishing these are outlined in Table 1, with a timeline in Table 2. The two main goals for the program, with a summary of the strategies to achieve them, are: Goal 1: Collect scientifically credible measures of the status and trends of North American bird populations at continental and regional scales. The North American Breeding Bird Survey will continue to support North American natural resource conservation through the collection of scientifically credible measures of the status and trends of continental bird populations. While doing this, the BBS will work to improve the science behind the program to better meet its mission and the changing needs of the avian conservation community. In partnership with collaborators, the BBS will address detection probability bias and habitat bias, improve analytical methods, and more fully assess and account for observer quality. Moreover, the BBS will improve the quality and breadth of avian population data through strategic increases in route density and the establishment of a Mexican BBS program. Goal 2: Ensure BBS data and analytical results are widely available and easily accessible for use by the avian conservation and management communities. At the heart of the BBS lies a four-million-record database containing more than 40 years of data on more than 600 bird species. These data are of no value if not well maintained, appropriately analyzed, and widely and easily accessible. The USGS has greatly improved data management and accessibility in recent years. Trend estimates were first made available via the Internet in the mid-1990s, followed closely by the raw data with baseline metadata and standard operating procedures. Nevertheless, numerous enhancements to data management and the usability of BBS results will greatly improve the ability of the BBS to serve avian conservation goals. The BBS needs to ensure that BBS data and results presented on the web site use the best data-management practices and statistical methods, with adequate documentation for users to understand them and any differences between different trend estimates. Moreover, the BBS needs to increase communication with BBS partners and stakeholders to ensure that it continues to meet the avian population status and trends needs of the conservation community and to encourage the development of new products. Working with collaborators, the BBS will develop tools for integrating environmental parameters like habitat change into the analyses, and for integrating BBS data with other avian survey results. In addition, the BBS will continue to improve data and database management through the incorporation of additional data and data fields, such as georeferenced stop locations and more complete metadata for the raw data and results, thus enhancing the uses that can be made of the data.

Circular↗
USGS1984

Geomorphic domains and linear features on Landsat images, Circle quadrangle, Alaska

A remote sensing study using Landsat images was undertaken as part of the Alaska Mineral Resource Assessment Program (AMRAP). Geomorphic domains A and B, identified on enhanced Landsat images, divide Circle quadrangle south of Tintina fault zone into two regional areas having major differences in surface characteristics. Domain A is a roughly rectangular, northeast-trending area of relatively low relief and simple, widely spaced drainages, except where igneous rocks are exposed. In contrast, domain B, which bounds two sides of domain A, is more intricately dissected showing abrupt changes in slope and relatively high relief. The northwestern part of geomorphic domain A includes a previously mapped tectonostratigraphic terrane. The southeastern boundary of domain A occurs entirely within the adjoining tectonostratigraphic terrane. The sharp geomorphic contrast along the southeastern boundary of domain A and the existence of known faults along this boundary suggest that the southeastern part of domain A may be a subdivision of the adjoining terrane. Detailed field studies would be necessary to determine the characteristics of the subdivision. Domain B appears to be divisible into large areas of different geomorphic terrains by east-northeast-trending curvilinear lines drawn on Landsat images. Segments of two of these lines correlate with parts of boundaries of mapped tectonostratigraphic terranes. On Landsat images prominent north-trending lineaments together with the curvilinear lines form a large-scale regional pattern that is transected by mapped north-northeast-trending high-angle faults. The lineaments indicate possible lithlogic variations and/or structural boundaries. A statistical strike-frequency analysis of the linear features data for Circle quadrangle shows that northeast-trending linear features predominate throughout, and that most northwest-trending linear features are found south of Tintina fault zone. A major trend interval of N.64-72E. in the linear feature data, corresponds to the strike of foliations in metamorphic rocks and magnetic anomalies reflecting compositional variations suggesting that most linear features in the southern part of the quadrangle probably are related to lithologic variations brought about by folding and foliation of metamorphic rocks. A second important trend interval, N.14-35E., may be related to thrusting south of the Tintina fault zone, as high concentrations of linear features within this interval are found in areas of mapped thrusts. Low concentrations of linear features are found in areas of most igneous intrusives. High concentrations of linear features do not correspond to areas of mineralization in any consistent or significant way that would allow concentration patterns to be easily used as an aid in locating areas of mineralization. The results of this remote sensing study indicate that there are several possibly important areas where further detailed studies are warranted.

Alaska↗
USGS2005

Significance of the precambrian basement and late Cretaceous thrust nappes on the location of tertiary ore deposits in the Oquirrh Mountains, Utah

The Oquirrh Mountains are located in north central Utah, in the easternmost part of the Basin and Range physiographic province, immediately south of the Great Salt Lake. The range consists of a northerly trending alignment of peaks 56 km long. Tooele and Rush Valleys flank the Oquirrh Mountains on the western side and Salt Lake and Cedar Valleys lie on the eastern side. The world class Bingham mine in the central part of the range hosts disseminated copper-bearing porphyry, skarn, base-and precious-metal vein and replacement ore deposits. The district includes the outlying Barneys Canyon disseminated-gold deposits. Disseminated gold in the Mercur mining district in the southern part of the range has become exhausted. The Ophir and Stockton base- and precious-metal mining districts in the range north of Mercur also are inactive. A geologic map of the range (Tooker and Roberts, 1998), available at a scale of 1:50,000, is a summation of U.S. Geological Survey (USGS) studies. Information about the range and its mining areas is scattered. This report summarizes map locations, new stratigraphic and structural data, and reexamined data from an extensive published record. Unresolved controversial geological interpretations are considered, and, for the first time, the complete geological evidence provides a consistent regional basis for the location of the ore deposits in the range. The geological setting and the siting of mineral deposits in the Oquirrh Mountains began with the formation of a Precambrian craton. Exposures of folded Proterozoic basement rocks of the craton, in the Wasatch Mountains east of Salt Lake City, were accreted and folded onto an Archean crystalline rock terrane. The accretion suture lies along the north flank of the Uinta Mountains. The western part of the accreted block was offset to northern Utah along a north-trending fault lying approximately along the Wasatch Front (Nelson and others, 2002), thereby creating a prominant basement barrier or buttress east of the Salt Lake area. The accretion suture along the north flank of the Uinta Anticline overlaps an earlier Precambrian east-west mobile zone, the Uinta trend (Erickson, 1976, Bryant and Nichols, 1988 and John, 1989), which extends westward across western Utah and into Nevada. A trace of the trend underlies the middle part of the Oquirrh Mountains. Its structure is recognized by disrupted Paleozoic stratigraphic units and fold and fault evidence of thrust faulting, intermittent local uplift and erosion, the alignment of Tertiary intrusives and associated ore deposits. Geologic readjustments along the trend continued intermittently through the Paleozoic, Cenozoic, Tertiary, and the development of clastic deposits along the shores of Pleistocene Lake Bonneville. Paleozoic sedimentary rocks were deposited on the craton platform shelf in westernmost Utah and eastern Nevada as the shelf subsided gradually and differentially. Debris was shed into two basins separated by the uplifted Uinta trend, the Oquirrh Basin on the south and Sublette Basin on the north. Sediments were derived from the craton to the east, the Antler orogenic zone on the west (Roberts, 1964), and locally from uplifted parts of the trend itself. Thick accumulations of clastic calcareous quartzite, shale, limestone, and dolomite of Lower and Upper Paleozoic ages are now exposed in the Oquirrh Mountains, the result of thrust faults. Evidence of decollement thrust faults in in the Wasatch Mountains during the Late Cretaceous Sevier orogeny, recognized by Baker and others (1949) and Crittenden (1961, is also recognized in the Oquirrh Mountains by Roberts and others (1965). During the late Cretaceous Sevier Orogeny, nappes were thrust sequentially along different paths from their western hinterland to the foreland. Five distinct nappes converged over the Uinta trend onto an uplifted west-plunging basement buttress east of the Oquirrh Mountains area: the Pass Canyon, Bingham,

Scientific Investigations Report↗
USGS2009

Pesticides in ground water in selected agricultural land-use areas and hydrogeologic settings in Pennsylvania, 2003-07

This report was prepared by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Agriculture (PDA) as part of the Pennsylvania Pesticides and Ground Water Strategy (PPGWS). Monitoring data and extensive quality-assurance data on the occurrence of pesticides in ground water during 2003–07 are presented and evaluated; decreases in the land area used for agriculture and corresponding changes in the use of pesticides also are documented. In the Pennsylvania ground waters assessed since 2003, concentrations of pesticides did not exceed any maximum contaminant or health advisory levels established by the U.S. Environmental Protection Agency; PPGWS actions are invoked by the PDA at fractions of these levels and were needed only in areas designated by the PDA for special ground-water protection. Previous investigations through 1998 of pesticides in Pennsylvania ground water identified land use, as a surrogate for pesticide use, and rock type of the aquifer combined with physiography as key hydrogeologic setting variables for understanding aquifer vulnerability to contamination and the common occurrence of atrazine and metolachlor in ground water. Of 20 major hydrogeologic settings in a framework established in 1999 for pesticide monitoring in Pennsylvania, 9 were identified as priorities for data collection in order to change the monitoring status from "inadequate" to "adequate" for the PPGWS. Agricultural and forested land-use areas are decreasing because of urban and suburban growth. In the nine hydrogeologic settings evaluated using 1992 and 2001 data, decreases of up to 12 percent for agricultural land and 10 percent for forested land corresponded to increases of up to 11 percent for urban land. Changes in agricultural pesticide use were computed from crop data. For example, from 1996 to 2004–05, atrazine use declined by about 15 percent to 1,314,000 lb/yr (pounds per year) and metolachlor use increased by about 20 percent to 895,000 lb/yr; these compounds are the two most-used agricultural pesticides statewide. In 2003–07, a baseline assessment of pesticides was conducted in five of nine hydrogeologic settings with inadequate monitoring data—the Blue Ridge crystalline and Triassic Lowland siliciclastic, Eastern Lake surficial, Devonian-Silurian carbonate, Great Valley siliciclastic, and Northeastern Glaciated surficial settings. Between 20 and 30 wells in each setting were monitored. Of the 126 wells sampled, 96 well-water samples were analyzed for at least 52 pesticide compounds at the USGS National Water Quality Laboratory (NWQL) using a method with a minimum reporting level (MRL) at or above 0.002 µg/L (micrograms per liter). Of the 96 well waters analyzed by NWQL, 43 had measureable concentrations of one or more pesticides. Atrazine and (or) deethylatrazine (CIAT), a degradation product of atrazine, were reported at or above the MRL in 39 of the 43 well waters. Neither atrazine nor CIAT were reported at concentrations exceeding 0.10 µg/L; all measured concentrations in these five settings were below PPGWS action levels. Metolachlor was present in 7 of the 43 well waters with measureable concentrations of 1 or more pesticides; however, concentrations were below the MRL. The other 30 samples (10 of 20 wells in the Blue Ridge crystalline and Triassic Lowland siliciclastic setting and all 20 wells in the Eastern Lake surficial setting) were analyzed for at least 19 pesticide compounds at the Pennsylvania Department of Environmental Protection Laboratory (PADEPL); the PADEPL reported no concentrations of pesticides at or above an MRL of 0.10 µg/L. Statistical tests using the NWQL analytical results showed correlations between pesticide occurrence and two indicators of water-quality degradation—the occurrence of total coliform bacteria and nitrate concentration. A 2 × 2 contingency-table test indicated a relation between presence or absence of atrazine or metolachlor and presence or absence of bacteria only for the 10 wells representing the Blue Ridge crystalline and Triassic Lowland siliciclastic setting. Results of Spearman’s rank test showed strong positive correlations in the Devonian-Silurian carbonate setting between 1) the number of pesticides above the MRLs and nitrate concentration, and 2) concentrations of atrazine and nitrate. Atrazine concentration and nitrate concentration also showed a statistically significant positive correlation in the Great Valley siliciclastic setting. An additional component of baseline monitoring was to evaluate changes in pesticide concentration in water from wells representing hydrogeologic settings most vulnerable to contamination from pesticides. In 2003, 16 wells originally sampled in the 1990s were resampled—4 each in the Appalachian Mountain carbonate, Triassic Lowland siliciclastic, Great Valley carbonate, and Piedmont carbonate settings. Nine of these wells, where pesticide concentrations from 1993 and 2003 were analyzed at the NWQL, were chosen for a paired-sample analysis using concentrations of atrazine and metolachlor. A statistically significant decrease in atrazine concentration was identified using the Wilcoxon signed-rank test (p = 0.004); significant temporal changes in metolachlor concentrations were not observed (p = 0.625). Monitoring in three areas of special ground-water protection, where selected pesticide concentrations in well water were at or above the PPGWS action levels, was done at wells BE 1370 (Berks County, Oley Township), BA 437 (Blair County, North Woodbury Township), and LN 1842 (Lancaster County, Earl Township). Co-occurrence of pesticide-degradation products with parent compounds was documented for the first time in ground-water samples collected from these three wells. Degradation products of atrazine, cyanazine, acetochlor, alachlor, and metolachlor were commonly at larger concentrations than the parent compound in the same water sample. Pesticide occurrence in water from wells neighboring the hot-spot wells was highly variable; however, the same sets of pesticide compounds that were present in wells BA 437, BE 1370, and LN 1842 were present to some degree in water from neighboring wells. To evaluate temporal changes in concentration, nonparametric statistical tests were used to determine overall and seasonal monotonic trends. Concentrations of alachlor, atrazine, metolachlor, and nitrate were examined using the 5-year (2003–07) and the long-term data from wells BA 437 and LN 1842 (1996–2007 and 1995–2007, respectively), and the long-term data for well BE 1370 (1998–2007); results showed either downward trends or no trends. Trends in acetochlor concentrations were tested only at well LN 1842 using the 5-year data; no trends were observed. Homogeneity of trend tests indicated statistically significant downward concentration trends in the long-term data were due to seasonal trends as follows: BA 437—alachlor and atrazine (summer); BE 1370—atrazine and metolachlor (winter) and alachlor (winter and spring); LN 1842—alachlor (summer and fall) and atrazine (spring and fall).

Pennsylvania↗
USGS2023

Hydrology, water-quality, and watershed characteristics in 15 watersheds in Gwinnett County, Georgia, water years 2002–20

The U.S. Geological Survey, in cooperation with Gwinnett County Department of Water Resources, established the Long-Term Trend Monitoring program in 1996 to monitor and analyze the hydrologic and water-quality conditions in Gwinnett County, Georgia. Gwinnett County is a suburban to urban area northeast of the city of Atlanta in north-central Georgia. The monitoring program currently consists of 15 watersheds ranging in size from 1.3 to about 161 square miles. This report synthesizes watershed characteristics and hydrologic and water-quality monitoring data collected for water years (WYs) 2002–20. The 15 study watersheds were characterized for land-surface elevations, average land-surface slopes, septic densities, sanitary sewer densities, and detention pond areas. Temporal patterns in watershed characteristics were determined for land cover (2001–19), percent imperviousness (2000–20), population density (2000–20), and building density (1950–2022). In 2001, most of the watersheds had at least 45 percent of their land cover composed of developed land cover groups, and by 2019, at least 59 percent of each watershed was developed. Land cover changes occurred most rapidly between 2004 and 2008 at most watersheds. Percent imperviousness in the study watersheds varied substantially and ranged from 14.75 to 55.13 percent in 2019. Precipitation and runoff were quantified at all study watersheds for WYs 2002–20, and the hydrologic cycle was evaluated both annually and seasonally. Several 1-year or longer droughts occurred during this period. Study area precipitation averaged 51.5 inches per year and runoff averaged 22.5 inches per year. Variations in annual runoff were largely determined by annual precipitation but were also dependent upon watershed storage. Runoff varied seasonally because of high evapotranspiration rates in the summer and changes in base flow associated with seasonal changes in watershed storage. Fifty-one percent of runoff in the study area occurred as base flow. Watersheds with higher imperviousness had higher stormflows because of increased surface runoff and lower base flows because of reduced infiltration that recharges watershed storage. Turbidity, water temperature, and specific conductance were continuously measured at each study site. These constituents varied seasonally, diurnally, and with streamflow. A minimum of two base-flow and six stormflow samples were collected per year at each watershed and were analyzed for 21 water-quality constituents (water temperature, laboratory specific conductance, pH, and turbidity, biochemical and chemical oxygen demand, suspended sediments, nutrients, base cations, trace metals, and total dissolved solids). Concentrations of most particulate constituents were approximately one-half or more orders of magnitude higher in stormflow samples than in base-flow samples. Total copper and zinc stormflow concentrations exceeded the national recommended aquatic life criteria for acute conditions to varying degrees. Annual loads and yields were estimated for 12 constituents (which include suspended sediments, nutrients, base cations, trace metals, and total dissolved solids) using a surrogate regression model approach and the Beale load estimator. Loads were typically higher for years with higher runoff. The proportional range of annual loads for total suspended solids, suspended-sediment concentrations, total phosphorus, and total lead, however, were 3.2 to 4.8 times larger than for annual runoff. Higher-than-expected annual sediment loads occurred in the years that also had some of the highest peak flows during the period, indicating that large storms are responsible for much of the sediment transport. Large development projects in proximity to streams also were related to years with high sediment loads. Yields from the Crooked Creek and North Fork Peachtree Creek watersheds were typically among the highest for 8 of the 12 constituents. These watersheds had the two highest amounts of developed medium plus high intensity land cover and the two highest percentages of imperviousness. Moderate to strong correlations were identified between seven of the constituent yields and the percentage of developed medium and high intensity land cover groups. Temporal trends in concentrations and loads were identified for 140 of the 300 possible watershed-time period-constituent combinations. There were substantially more negative than positive temporal trends identified during WYs 2003–10, whereas the number of negative and positive temporal trends were similar during WYs 2010–20. Measures of sediment transport had the most negative temporal trends. A few watersheds had consistent trends across several constituents; however, these trends did not appear to be associated with temporal changes in development or imperviousness. This study provides a thorough assessment of watershed characteristics, hydrology, and water-quality conditions and trends for the 15 study watersheds and can be used to identify possible factors that affect runoff and water quality and determine changes in water-quality conditions. Watershed managers can use these data and analyses to inform management decisions regarding the designated uses of streams, minimization of flooding, protection of aquatic habitats, and optimization of the effectiveness of best management practices.

Georgia↗
USGS1993

National water summary 1990-91: Hydrologic events and stream water quality

National Water Summary 1990-91 Hydrologic Events and Stream Water Quality was planned to complement existing Federal-State water-quality reporting to the U.S. Congress that is required by the Clean Water Act of 1972. This act, formally known as the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500), and its amendments in 1977,1979,1980,1981,1983, and 1987, is the principal basis for Federal-State cooperation on maintaining and reporting on water quality in the United States. Under section 305(b) of the Clean Water Act, the States must designate uses for waterbodies, biennially assess whether the waterbodies meet designated uses, and report to the U.S. Environmental Protection Agency (EPA), which in turn summarizes the findings of the State assessments in a biennial National Water Quality Inventory report to the Congress. This volume of the National Water Summary uses a nationally consistent data base and methods of statistical analysis to document stream water quality in the United States, Puerto Rico, and the Western Pacific Islands. As a basis for preparation of this report, the U.S. Geological Survey (uses) created a data base of waterquality data from about 2,900 stream water-quality monitoring stations in the United States (Lanfear, 1993). These data, which were extracted primarily from the uses National Water Information System (NWIS) and supplemented with data from the EPA national data base known as STORET, consisted mostly of water-chemistry and physical-sediment data. About 1,400 of these stations met a criterion, used in this volume for trends analysis of data, of having a period of record that began before water year 1980. (A water year is the period from October 1 through September 30 and is identified by the calendar year at the end of the period.) Inasmuch as the determination of trends requires about 10 years of data, few biological data were suitable for trends analysis because biological indicators of water quality were not being collected extensively by water year 1980. Also, because of the lack of long-term data, an assessment of the water quality of lakes and reservoirs is not included in this National Water Summary . Constituent and waterproperty data were selected from this data base and analyzed with statistical techniques that have been used extensively by the uses to summarize conditions and trends in water quality. (Throughout the remainder of this article, the term "constituent" is used also to represent water properties, such as pH and alkalinity.) Selected results from this analysis are presented graphically, both by State and nationally, in this volume. The data base created for preparation of this volume and the resulting nationally consistent statistical analysis of these data provide a unique opportunity to compare and contrast stream water-quality conditions and trends nationally and State by State. Because of the complexity of water quality and the natural seasonal and diurnal variations in the concentrations of waterquality constituents, the determination of trends in water quality requires a relatively long period of record. Trends in constituent concentrations in the State summaries in this volume were calculated for one or more of four periods water years 1970-89,1975-89,1980- 89, and 1982-89. Unfortunately, few water-quality monitoring stations have periods of record of more than 10 or 15 years, and therefore most analyses in the State summaries were done for 8- or 10-year periods. Although interest in water quality has continued to heighten since passage of the Clean Water Act, funds for support of data-collection programs are limited and data records of many of the constituents now of current concern, especially organic constituents, do not exist or are less than 10-years long; consequently only a modest number of organic constituents are presented in this volume. Discussion of conditions and trends in water quality in this National Water Summary also draw upon information about land use, population, water use, application of agricultural chemicals in rural areas, the siting of industrial facilities, and other ancillary information. Because the results of analysis of a restricted number of constituents are presented in this volume, State 305(b) reports also are cited in the discussion of water quality in each State. The following discussion is an overview of the three parts of this 1990-91 National Water Summary - "Hydrologic Conditions and Water-Related Events, Water Years 1990-91," "Hydrologic Perspectives on Water Issues," and "State Summaries of Stream Water Quality."

Water Supply Paper↗
USGS2011

Influences of environmental and anthropogenic features on greater sage-grouse populations, 1997-2007

The Greater Sage-Grouse (Centrocercus urophasianus), endemic to western North Amer-ica, is of great conservation interest. Its popula-tions are tracked by spring counts of males at lek sites. We explored the relations between trends of Greater Sage-Grouse lek counts from 1997 to 2007 and a variety of natural and anthropogenic fea-tures. We found that trends were correlated with several habitat features, but not always similarly throughout the range. Lek trends were positively associated with proportion of sagebrush (Artemisia spp.) cover, within 5 km and 18 km. Lek trends had negative associations with the coverage of agriculture and exotic plant species. Trends also tended to be lower for leks where a greater pro-portion of their surrounding landscape had been burned. Few leks were located within 5 km of developed land and trends were lower for those leks with more developed land within 5 km or 18 km. Lek trends were reduced where communi-cation towers were nearby, whereas no effect of power lines was detected. Active oil or natural gas wells and highways, but not secondary roads, were associated with lower trends. Effects of some anthropogenic features may have already been manifested before our study period and thus not have been detected in this analysis. Results of this range-wide analysis complement those from more intensive studies on smaller areas. Our findings are important for identifying features that could threaten Greater Sage-Grouse populations.

Book chapter↗
USGS1996

Long-term geochemical surveillance of fumaroles at Showa-Shinzan dome, Usu volcano, Japan

This study investigates 31 years of fumarole gas and condensate (trace elements) data from Showa-Shinzan, a dacitic dome-cryptodome complex that formed during the 1943-1945 eruption of Usu volcano. Forty-two gas samples were collected from the highest-temperature fumarole, named A-1, from 1954 (800??C) to 1985 (336??C), and from lower-temperature vents. Condensates were collected contemporaneously with the gas samples, and we reanalyzed ten of these samples, mostly from the A-1 vent, for 32 cations and three anions. Modeling using the thermochemical equilibrium program, SOLVGAS, shows that the gas samples are mild disequilibrium mixtures because they: (a) contain unequilibrated sedimentary CH4 and NH3; (b) have unequilibrated meteoric water; or (c) lost CO, either by air oxidation or by absorption by the sodium hydroxide sampling solution. SOLVGAS also enabled us to restore the samples by removing these disequilibrium effects, and to estimate their equilibrium oxygen fugacities and amounts of S2 and CH4. The restored compositions contain > 98% H2O with minor to trace amounts of CO2, H2, HCl, SO2, HF, H2S, CO, S2 and CH4. We used the restored gas and condensate data to test the hypotheses that these time-series compositional data from the dome's fumaroles provide: (1) sufficient major-gas data to analyze long-term degassing trends of the dome's magma-hydrothermal system without the influence of sampling or contamination effects; (2) independent oxygen fugacity-versus-temperature estimates of the Showa-Shinzan dacite; (3) the order of release of trace elements, especially metals, from magma; and (4) useful information for assessing volcanic hazards. The 1954-1985 restored A-1 gas compositions confirm the first hypothesis because they are sufficient to reveal three long-term degassing trends: (1) they became increasingly H2O-rich with time due to the progressive influx of meteoric water into the dome; (2) their C/S and S/Cl ratios decreased dramatically while their Cl/F ratios stayed roughly constant, indicating the progressive outgassing of less soluble components (F ??? Cl > S > C) from the magma reservoir; and (3) their H2O/H2, CO2/CO and H2S/SO2 ratios increased significantly in concert with equilibrium changes expected for the ??? 500??C temperature drop. When plotted against reciprocal temperature, the restored-gas log oxygen fugacities follow a tight linear trend from < NNO + 0.5 at > 800??C to NNO + 2.5 at ??? 400??C. This trend largely disproves the second hypothesis because the oxygen fugacities for the < 800??C restored gases can only be explained by mixing of hot magmatic gases with ??? 350??C steam from superheated meteoric water. But above 800??C this trend intersects the opposing linear trend for other Usu eruptive products, implying a log oxygen fugacity of -11.45 at 902??C for the Showa-Shinzan magma. The time-series trace-element data also disprove the third hypothesis because rock- and incrustation-particle contaminants in the condensates account for most of the trace-element variation. Nonetheless, highly volatile elements like B and As are relatively unaffected by this particle contamination, and they show similar time-series trends as Cl and F. Finally, except for infrequent sampling around the 1977 Usu eruption, the results generally confirm the fourth hypothesis, since the time-series trends for the major gases and selected trace elements indicate that, with time, the system cooled, degassed and was infiltrated by meteoric water, all of which are positive signs that volcanic activity declined over the 31-year history. This study also suggests that second boiling of shallow magma within and possibly beneath the cryptodome sustained magmatic degassing for at least 20 years after emplacement.

Journal of Volcanology and Geothermal Research↗
USGS2022

Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai‘i

Endemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (BINWRC) was created for conservation of endangered Hawaiian forest birds and their habitats. Surveys have been conducted at two units of BINWRC to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and pasture, and two strata at the KFU: upper (>1524 m elevation) and lower (<1524 m). In all years, ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), and Hawai‘i ‘amakihi (Chlorodrepanis virens virens) were the most abundant species at HFU. The three endangered forest bird species, Hawai‘i ‘ākepa (Loxops coccineus), ‘alawī (Loxops mana, also known as Hawai‘i creeper) and ‘akiapōlā‘au (Hemignathus wilsoni), had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai‘i ‘amakihi and warbling white-eye (Zosterops japonicus) at much lower densities. At HFU we found a continuation of several trends observed in previous analyses from 1987–2012, with most species’ trends upward in pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, when we looked at the most recent decade at HFU, more species were showing downward trends in all three strata. At KFU results were mixed, with more species’ trends downward in the upper stratum and more species’ trends upward in the lower stratum. Populations of endangered forest species were either locally extirpated at KFU or in numbers too low to reliably estimate population densities. Both units in the BINWRC are important for conservation of forest birds on Hawai‘i Island, and our results show that HFU supports the majority of the three endangered forest bird species found on Hawai‘i Island. Our analysis also shows the importance of continuous monitoring and timely analysis to track forest bird populations. With the additional data provided by continued surveys, we determined conclusive population trends for species whose trends were previously inconclusive. Knowing current population densities, abundances, and trends allows managers to evaluate and adapt management actions to support forest bird conservation at the BINWRC.

Hawaii↗
USGS2017

Recent stability of resident and migratory landbird populations in National Parks of the Pacific Northwest

Monitoring species in National Parks facilitates inference regarding effects of climate change on population dynamics because parks are relatively unaffected by other forms of anthropogenic disturbance. Even at early points in a monitoring program, identifying climate covariates of population density can suggest vulnerabilities to future change. Monitoring landbird populations in parks during the breeding season brings the added benefit of allowing a comparative approach to inference across a large suite of species with diverse requirements. For example, comparing resident and migratory species that vary in exposure to non-park habitats can reveal the relative importance of park effects, such as those related to local climate. We monitored landbirds using breeding-season point-count data collected during 2005–2014 in three wilderness areas of the Pacific Northwest (Mount Rainier, North Cascades, and Olympic National Parks). For 39 species, we estimated recent trends in population density while accounting for individual detection probability using Bayesian hierarchical N -mixture models. Our analyses integrated several recent developments in N -mixture modeling, incorporating interval and distance sampling to estimate distinct components of detection probability while also accommodating count intervals of varying duration, annual variation in the length and number of point-count transects, spatial autocorrelation, random effects, and covariates of detection and density. As covariates of density, we considered metrics of precipitation and temperature hypothesized to affect breeding success. We also considered effects of park and elevational stratum on trend. Regardless of model structure, we estimated stable or increasing densities during 2005–2014 for most populations. Mean trends across species were positive for migrants in every park and for residents in one park. A recent snowfall deficit in this region might have contributed to the positive trend, because population density varied inversely with precipitation-as-snow for both migrants and residents. Densities varied directly but much more weakly with mean spring temperature. Our approach exemplifies an analytical framework for estimating trends from point-count data, and for assessing the role of climatic and other spatiotemporal variables in driving those trends. Understanding population trends and the factors that drive them is critical for adaptive management and resource stewardship in the context of climate change.

Ecosphere↗
USGS2020

Regional crop water use assessment using Landsat-derived evapotranspiration

Reliable information on water use and availability at basin and field scales are important to ensure the optimized constructive uses of available water resources. This study was conducted with the specific objective to estimate Landsat-based actual evapotranspiration (ETa) using the Operational Simplified Surface Energy Balance (SSEBop) model across the state of South Dakota (SD), USA for the 1986–2018 (33-year) period. Validated ETa estimations (r 2 = 0.91, PBIAS = −4%, and %RMSE = 11.8%) were further used to understand the crop water-use characteristics and existing historic mono-directional (increasing/decreasing) trends over the eastern (ESD) and western (WSD) regions of SD. The crop water-use characteristics indicated that the annual cropland water uses across the ESD and WSD were more or less met by the precipitation amounts in the area. The ample water supply and distribution have led to high rainfed and low percentage of irrigated cropland (~2.5%) in the state. The WSD faced greater crop-water use reductions than the ESD during drought periods. The landscape ETa responses across the state were found to be more sensitive than precipitation for the drought impact assessments. The Mann Kendall trend analysis revealed the absence of a significant trend ( p > 0.05) in annual ETa at a regional scale due to the varying weather conditions in the state. However, about 12% and 9% cropland areas in the ESD and WSD, respectively, revealed a significant mono-directional trend at pixel scale ETa. Most of the pixels under significant trend showed an increasing trend that can be explained by the shift in agricultural practices, increased irrigated cropland area, higher productions, moisture regime shifts, and decreased risk of farming in the dry areas. The decreasing trend pixels were clustered in mid-eastern SD and could be the result of dynamic conversion of wetlands to croplands and decreased irrigation practices in the region. This study also demonstrates the tremendous potential and robustness of the SSEBop model, Landsat imagery, and remote sensing-based ETa modelling approaches in estimating consistent spatially distributed evapotranspiration.

South Dakota↗
USGS2021

Runoff response to directional land cover change across reference basins in the conterminous United States

Land cover change plays a critical role in influencing hydrological responses. Change in land cover has impacted runoff across basins with substantial human interference; however, the impacts in basins with minimal human interference have been studied less. In this study, we investigated the impacts of directional land cover changes (forest to/from combined grassland and shrubland) in runoff coefficient (RC; ratio of runoff to precipitation) and runoff volume across 603 low human interference reference basins in the conterminous United States (CONUS). The results indicate basins with significant ( p <0.05) increasing trends in runoff and RC were across the northeast and northwest regions of CONUS, and basins with decreasing trends were in the southern CONUS region. A unit percent increase in basin area from grassland and shrubland to forest was associated with a ∼4% decrease in RC across basins with decreasing RC trends. Similarly, a unit percent increase in basin area from forest to a combined grassland and shrubland was associated with a ∼1% increase in RC across increasing RC trend basins. Runoff volume was decreased (increased) by ∼25 × 10 6 m 3 yr −1 (∼9 × 10 6 m 3 yr −1 ) across basins with decreasing (increasing) trends in runoff and RC. When relating runoff volume with the area of directional land cover changes, each 1 km 2 increase in area from grassland and shrubland to forest resulted in a decrease of ∼530,000 m 3 runoff volume across basins with decreasing trends. In contrast, each 1 km 2 increase in area from forest to grassland and shrubland increased runoff volume by ∼200,000 m 3 across increasing trend basins. Basins in the southern region of CONUS were more impacted by runoff parameters (RC and runoff volume) from directional land cover changes than basins in the northern region. The findings of this study are useful for planning and managing water availability for sustainable and adaptive water resources management at regional scales.

Advances in Water Resources↗
USGS1999

Mining geology of the Pond Creek seam, Pikeville Formation, Middle Pennsylvanian, in part of the Eastern Kentucky Coal Field, USA

The Pond Creek seam is one of the leading producers of coal in the Eastern Kentucky Coal Field. The geologic factors that affect mining were investigated in several underground mines and categorized in terms of coal thickness, coal quality, and roof control. The limits of mining and thick coal are defined by splitting along the margin of the coal body. Within the coal body, local thickness variation occurs because of (1) leader coal benches filling narrow, elongated depressions, (2) rider coal benches coming near to or merging with the main bench, (3) overthrust coal benches being included along paleochannel margins, (4) cutouts occuring beneath paleochannels, and (5) very hard and unusual rock partings occuring along narrow, elongated trends. In the study area, the coal is mostly mined as a compliance product: sulfur contents are less than 1% and ash yields are less than 10%. Local increases in sulfur occur beneath sandstones, and are inferred to represent post-depositional migration of fluids through porous sands into the coal. Run-of-mine quality is also affected by several mine-roof conditions and trends of densely concentrated rock partings, which lead to increased in- and out-of-seam dilution and overall ash content of the mined coal. Roof control is largely a function of a heterolithic facies mosaic of coastal-estuarine origin, regional fracture trends, and unloading stress related to varying mine depth beneath the surface. Lateral variability of roof facies is the rule in most mines. The largest falls occur beneath modern valleys and parallel fractures, along paleochannel margins, within tidally affected 'stackrock,' and beneath rider coals. Shale spalling, kettlebottoms, and falls within other more isolated facies also occur. Many of the lithofacies, and falls related to bedding weaknesses within or between lithofacies, occur along northeast-southwest trends, which can be projected in advance of mining. Fracture-related falls occur independently of lithofacies trends along northwest-southeast trends, especially beneath modern valleys where overburden thickness decreases sharply. Differentiating roof falls related to these trends can aid in predicting roof quality in advance of mining.The Pond Creek-Lower Elkhorn seam has been an important exploration target because it typically has very low sulfur contents and ash yields. Geologic research in several large Pond Creek mines suggested variability in roof quality and coal thickness. Due to mine access, geologic problems encountered during mining are documented and described.

International Journal of Coal Geology↗