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USGS2014

Land-margin ecosystem hydrologic data for the coastal Everglades, Florida, water years 1996-2012

Mangrove forests and salt marshes dominate the landscape of the coastal Everglades (Odum and McIvor, 1990). However, the ecological effects from potential sea-level rise and increased water flows from planned freshwater Everglades restoration on these coastal systems are poorly understood. The National Park Service (NPS) proposed the South Florida Global Climate Change Project (SOFL-GCC) in 1990 to evaluate climate change and the effect from rising sea levels on the coastal Everglades, particularly at the marsh/mangrove interface or ecotone (Soukup and others, 1990). A primary objective of SOFL-GCC project was to monitor and synthesize the hydrodynamics of the coastal Everglades from the upstream freshwater marsh to the downstream estuary mangrove. Two related hypotheses were set forward (Nuttle and Cosby, 1993): 1. There exists hydrologic conditions (tide, local rainfall, and upstream water deliveries), which characterize the location of the marsh/mangrove ecotone along the marine and terrestrial hydrologic gradient; and 2. The marsh/mangrove ecotone is sensitive to fluctuations in sea level and freshwater inflow from inland areas. Hydrologic monitoring of the SOFL-GCC network began in 1995 after startup delays from Hurricane Andrew (August 1992) and organizational transfers from the NPS to the National Biological Survey (October 1993) and the merger with the U.S. Geological Survey (USGS) Biological Research Division in 1996 (Smith, 2004). As the SOFL-GCC project progressed, concern by environmental scientists and land managers over how the diversion of water from Everglades National Park would affect the restoration of the greater Everglades ecosystem. Everglades restoration scenarios were based on hydrodynamic models, none of which included the coastal zone (Fennema and others, 1994). Modeling efforts were expanded to include the Everglades coastal zone (Schaffranek and others, 2001) with SOFL-GCC hydrologic data assisting the ecological modeling needs. In 2002, as a response for a more interdisciplinary science approach to understanding the coastal Everglades ecological system, the SOFL-GCC hydrology project was integrated into the “Dynamics of Land-Margin Ecosystems: Historical Change, Hydrology, Vegetation, Sediment, and Climate” study (Smith and others, 2002). Data from the ongoing study has been useful in providing an empirical hydrologic baseline for the greater Everglades ecosystem restoration science and management needs. The hydrology network consisted of 13 hydrologic gaging stations installed in the southwestern coastal region of Everglades National Park along three transects: Shark River (Shark or SH) transect, Lostmans River (Lostmans or LO) transect, and Chatham River (Chatham or CH) transect (fig. 1). There were five paired surface-water/groundwater gaging stations on the Shark transect (SH1, SH2, SH3, SH4, and SH5) and one stage gaging station (BSC) in the Big Sable Creek; four paired surface-water/groundwater gaging stations on the Lostmans transect (LO1, LO2, LO3, and LO4); and three paired surface-water/groundwater gaging stations on the Chatham transect (CH1, CH2, and CH3). Both surface-water and groundwater levels, salinities, and temperatures were monitored at the paired gaging stations. Rainfall was recorded at marsh and open canopy gaging stations. This report details the study introduction, method, and description of data collected, which are accessible through the final instantaneous hydrologic dataset stored in the USGS South Florida Information Access (SOFIA) South Florida Hydrology Database website, http://sofia.usgs.gov/exchange/sfl_hydro_data/location.html#brdlandmargin .

Florida↗

USGS2023

Seismic source characterization in central and eastern United States

This report documents earthquake geology studies conducted in the central and eastern United States (CEUS) between 2018 and 2023. The overarching goal of the earthquake geology studies was to identify and characterize fault sources in the New Madrid seismic zone, the eastern Tennessee seismic zone, and the Charleston seismic zone. These studies primarily relied on the interpretation of high-resolution topography, morphotectonic analysis of 10-meter (m) digital elevation models, field reconnaissance, and integration with new and existing subsurface datasets. Results from each study are placed into a seismic hazard framework. The first two chapters focus on the New Madrid seismic zone, which is the most seismically active region in the CEUS, to better characterize the southern extent of the Reelfoot fault in the Obion River valley, and identify and characterize proposed faults along the margins of Crowleys Ridge in the center of the Mississippi River embayment. Crowleys Ridge is a ~320-kilometer (km) long landform that has been proposed to be formed by intermittent faulting or erosion from the Mississippi River. Legacy seismic reflection data documented Eocene, Mesozoic, and older strata offset by faults on the margins of the ridge (Van Arsdale et al., 1999). A morphotectonic analysis of the topography along Crowleys Ridge indicated southward increases in catchment hypsometric integral and slope. Neotectonic mapping on high-resolution lidar data revealed a series of subparallel linear fault and fold scarps along the margins of Crowleys Ridge. These scarps offset previously mapped fluvial and alluvial surfaces that were <56 thousand years ago (ka) (Rittenour et al., 2007). Integration of new seismic reflection and airborne electromagnetic data, legacy seismic data, with the landscape morphotectonic analysis and neotectonic mapping supports the interpretation that Crowleys Ridge is bound by faults that have been active in the late Quaternary but do not experience modern seismicity. By placing these newly characterized faults into the regional framework, the Crowleys Ridge faults can be interpreted as thrust faults associated with stepovers in the overall dextral fault system, similar to the Reelfoot fault. The results of these studies indicate that seismicity has migrated eastward during the late Quaternary, with the Reelfoot fault accommodating much of the modern-day strain. The Reelfoot fault ruptured in the 1811-1812 New Madrid earthquake sequence (Fuller, 1912) and has a record of past large earthquakes (Tuttle et al., 2002; 2019). Whereas the northern extent of the fault intersects the Mississippi River and has well-expressed surface deformation, questions remained regarding the southern limit of seismicity, deformation, and overall fault length. Analysis of <25 ka river terraces along the Obion River valley in western Tennessee revealed subtle fold scarps, with increased magnitudes of deformation on progressively older terraces, indicative of a longer record of fault movement than has been documented by paleoseismic and paleoliquefaction studies alone (e.g., Kelson et al., 1996; Gold et al., 2019; Tuttle et al., 2019). The third chapter integrates surface and subsurface data to assess the landscape record of surface deformation in the eastern Tennessee seismic zone (ETSZ), which is the second most seismically active region in the CEUS. Seismicity in the ETSZ is deep (5-26 km) and focused in the Proterozoic rock below the Paleozoic detachment. Although the region has experienced moderate (≤ Mw 4.8) seismicity in the instrumental record, the lack of a large historical earthquake and limited paleoseismic and paleoliquefaction evidence of prehistoric large ground shaking events have made seismic hazard characterization of the region challenging. Two models have emerged to predict the style and orientation of active surface deformation in the ETSZ. One suggests that surface rupturing earthquakes would exploit pre-existing faults along the regional structural grain (Cox et al., 2022). The second model advocates for primarily strike-slip motion on east-west or north-south faults, following analyses of recent seismicity (Chapman et al., 1997; Dunn and Chapman, 2006; Daniels and Peng, 2022) and the modern stress field (Levandowski et al., 2018). In our analysis, neotectonic mapping of high-resolution lidar data reveals a concentration of lineaments with east-west orientations, with some corresponding to previously mapped east-west faults that crosscut the northeast-southwest regional structural grain from the Paleozoic orogeny. A morphotectonic analysis of catchments and river segments within the same lithology indicates subtle differences that may be indicative of a longer-term tectonic uplift signal. These changes in morphotectonic metrics spatially correspond to newly mapped lineaments and previously mapped east-west trending faults. Within a regional framework, we suggest that diffuse surface deformation associated with deep seismicity is accommodated on a network on east-west faults. However, further work is needed to better understand the potential late Pleistocene fault activity of these lineaments, and we propose that the ETSZ is still best characterized as an area source in seismic hazard models. The final chapter presents preliminary work to create a geographic information system (GIS) database of recent studies analyzing surface and subsurface datasets and interpretations in the Charleston seismic zone, South Carolina. This GIS database will serve as a foundation for future work to analyze new quality level 1 (QL1; <0.5 m resolution) lidar data over the 1886 magnitude (M) 7 Charleston epicentral region to identify possible fault source sources responsible for the 1886 or other surface-rupturing events. This chapter briefly summarizes three new subsurface datasets, including seismic reflection (Pratt et al., 2022; Liberty, 2022) and seismicity data (Chapman et al., 2016), and one new surface dataset (Marple and Hurd, 2020), and their interpretations of potentially active lineaments and faults in the region.

central and eastern United States↗

USGS2016

Potential effects of alterations to the hydrologic system on the distribution of salinity in the Biscayne aquifer in Broward County, Florida

To address concerns about the effects of water-resource management practices and rising sea level on saltwater intrusion, the U.S. Geological Survey in cooperation with the Broward County Environmental Planning and Community Resilience Division, initiated a study to examine causes of saltwater intrusion and predict the effects of future alterations to the hydrologic system on salinity distribution in eastern Broward County, Florida. A three-dimensional, variable-density solute-transport model was calibrated to conditions from 1970 to 2012, the period for which data are most complete and reliable, and was used to simulate historical conditions from 1950 to 2012. These types of models are typically difficult to calibrate by matching to observed groundwater salinities because of spatial variability in aquifer properties that are unknown, and natural and anthropogenic processes that are complex and unknown; therefore, the primary goal was to reproduce major trends and locally generalized distributions of salinity in the Biscayne aquifer. The methods used in this study are relatively new, and results will provide transferable techniques for protecting groundwater resources and maximizing groundwater availability in coastal areas. The model was used to (1) evaluate the sensitivity of the salinity distribution in groundwater to sea-level rise and groundwater pumping, and (2) simulate the potential effects of increases in pumping, variable rates of sea-level rise, movement of a salinity control structure, and use of drainage recharge wells on the future distribution of salinity in the aquifer. Results from the simulation of historical conditions indicate that the model generally represents the observed greater westward extent of elevated salinity in the central part of the intruded area relative to the northern and southernmost parts of the intruded area. Results of sensitivity testing indicate that the extent of elevated salinity is most sensitive to pumping in areas where the source of saltwater is largely offshore, from the Atlantic Ocean, and is most sensitive to sea-level rise in areas where the source of salinity is downward leakage of brackish water from canals. Simulations of future scenarios indicate that increases in pumping near the existing interface may cause the interface to advance and decreases in pumping may cause it to retreat. Climatic effects, such as periods of prolonged drought or high precipitation, may augment or counteract long-term effects of changes in pumping on aquifer salinity at well fields. With increasing rates of sea-level rise, the freshwater-saltwater interface advances progressively inland, and flow-averaged salinities at well fields near the existing interface increase commensurately. Hypothetical southeastward (downstream) re-positioning of the existing G–54 salinity-control structure may prevent the interface from moving northwestward along and near the North New River canal, but beneficial effects are localized. Implementation of freshwater recharge wells in the city of Hallandale Beach may also have only a localized freshening effect in the aquifer and little appreciable effect on the freshwater-saltwater interface or on concentrations of salinity at well fields. Model accuracy and use are limited by uncertainty in the physical properties and boundary conditions of the system, uncertainty in historical and future conditions, and generalizations made in the mathematical relationships used to describe the physical processes of groundwater flow and transport. Because of these limitations, model results should be considered in relative rather than absolute terms. Nonetheless, model results do provide useful information on the relative scale of response of the system to changes in pumping distribution, sea-level rise, and mitigation activities.

Florida↗

USGS2012

The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism

The thick sequence of Miocene lava flows exposed on Steens Mountain in southeastern Oregon is well known for containing a detailed record of a reversed‐to‐normal geomagnetic polarity transition. Paleomagnetic samples were obtained from the sequence for a combined study of the directional and intensity variations recorded; the paleointensity study is reported in a companion paper. This effort has resulted in the first detailed history of total geomagnetic field behavior during a reversal of polarity. A comparison of the directional variation history of the reversed and normal polarity intervals on either side of the transition with the Holocene record has allowed an estimate of the duration of these periods to be made. These time estimates were then used to calculate accumulation rates for the volcanic sequence and thereby provide a means for estimating time periods within the transition itself. The polarity transition was found to consist of two phases, each with quite different characteristics. At the onset of the first phase, a one‐third decrease in magnetic field intensity may have preceded the first intermediate field directions by about 600 years. Changes in field direction were confined near the local north‐south vertical plane when the actual reversal in direction occurred and normal polarity directions may have been attained within 550±150 years. The end of the first phase of the transition was marked by a brief (possibly 100–300 years) period with normal polarity and a pretransitional intensity which suggests a quasi‐normal dipole field structure existed during this interval. The second phase of the transition was characterized by a return to very low field intensities with the changes in direction describing a long counterclockwise loop in contrast to the earlier narrowly constrained changes. This second phase lasted 2900±300 years, and both normal directions and intensities were recovered at the same time. Both directional and intensity data document very erratic geomagnetic field behavior during the polarity transition. Changes in magnetic field direction were variable and occurred either (1) in a regular, progressive manner, (2) with sudden, extremely rapid angular changes (58°±21°/year), or (3) with little or no movement for periods of the order of 600±200 years. Changes in magnetic intensity occurred in a like manner and were sometimes correlated with changes in direction, but during other periods both directional and intensity changes occurred independently. Directional changes following the polarity transition occurred in a seemingly normal manner, although intensity fluctuations attest to some instability of the newly reestablished dipole.

Journal of Geophysical Research B: Solid Earth↗

USGS2025

The 3D National Topography Model Call for Action—Part 2: The Next Generation 3D Elevation Program

The three-dimensional (3D) National Topography Model initiative to integrate elevation and hydrography data includes the next generation of hydrography data from the 3D Hydrography Program and the next generation of elevation data from the 3D Elevation Program (3DEP). The first-ever collection of light detection and ranging (lidar) data for the nation (IfSAR for Alaska) provides a critical baseline reference, and the addition of multiple repeat elevation mapping projects as part of the next generation of 3DEP would substantially expand analysis capabilities. As the U.S. Geological Survey (USGS) is closing in on our goal of complete coverage with 3DEP data available or in progress for 98.3 percent of the Nation at the end of fiscal year 2024, the USGS is already transitioning to the next generation of 3DEP. Based on the 3D Nation Study results and input from a broad range of stakeholders, the USGS National Geospatial Program has finalized a new design for 3DEP that provides increased lidar quality levels and refresh rates. The new program is designed with more flexibility to meet changing user needs and take advantage of improvements in mapping technologies. The program will aim to expand the level of interagency coordination for topobathymetric lidar acquisition for inland rivers. The next generation of 3DEP will also aim to emphasize research, including advancing program design, products, and services and engaging and leveraging the evolving 3D industry. Research goals also include becoming more flexible in meeting user needs and taking advantage of evolving remote-sensing technologies. The program also plans to move from focusing on producing standard products to producing a concept of a 3D Nation Ecosystem with a variety of inputs, products, and services.

Circular↗

USGS1977

Surficial and applied surficial geology of the Belchertown Quadrangle, Massachusetts

Till and stratified drift overlie maturely dissected topography in the Belchertown quadrangle, an area that straddles the New England Upland and Connecticut Valley Lowland in central Massachusetts. Lower Paleozoic, massive quartzo-feldspathic gneiss, quartzite and schist of the Pelham dome and Devonian granodiorite and quartz diorite of the Belchertown intrusive complex are in contact with Triassic arkosic fanglomerate and basalt along a lengthy normal fault separating the New England Upland from the Connecticut Valley Lowland. The orientation of striae, roches moutonnees, and streamline ridges indicate that the last Wisconsinian glacier advanced generally south 12? east. This glacier removed several meters of rock from the upland and an unknown larger quantity from the preglacial valley of the Connecticut River. Till is thin in the uplands, but several tens of feet of drift overlie bedrock in the lowland. Three lithic facies of sandy, clast-rich, non-compact, subarkosic till derived from the three major source rocks rest on bedrock or on highly weathered, compact, clast-poor, fissile probably older till. The mean for all upper till is 69.6% sand, 21.7% silt, and 8.8% clay; lower till consists of 48% sand, 23% silt and 29% clay. Mud-rich, compact, sparsely stony till in drumlins in and along the flank of the Connecticut Valley Lowland is composed of 51.5% sand, 28% silt, and 20.5% clay. Upper tills are facies equivalent deposits of the youngest Wisconsinian drift. Lower till is compact deeply weathered, jointed and stained suggesting it is correlative with other lower till in New England deposited by an earlier Wisconsinian glacier. Drumlin till may be a facies equivalent of a lower till or a mud-rich upper till derived from earlier glaciolacustrine deposits. Upper and lower till of the Belchertown quadrangle is texturally similar to other New England upper and lower tills to which they are equivalent. Both tills are interpreted as lodgment till derived from similar bedrock terrane by two different glaciers. The older glacier incorporated mud-rich saprolite producing a fine grained till, while the younger glacier eroded fresh bedrock or a thin regolith produced by mechanical weathering. During stagnation zone retreat of the last glacier, stratified drift was deposited by melt water in, on, alongside or down valley from stagnant ice. The absence of stratified drift along upland divides indicates that stagnation did not begin till large nunataks were emergent. Kame terraces, kame deltas, and ice channel fillings indicate that melt water flowed along stagnant ice and emptied into temporary proglacial lakes. As downwasting progressed, water was able to drain at lower elevation into expanding lakes, the last of which merged with northward-expanding proglacial Lake Hitchcock in the Connecticut Valley. Initial melt water drainage to the southeast was followed by drainage to the southwest to the ancestral Chicopee River. With the opening of the Narrows, Lake Hitchcock expanded northward and eastward to form the Amherst embayment into which melt water from the eastern uplands drained. Sand and gravel overlying varves in the Amherst embayment was deposited in late-glacial Lake Lawrence, which coalesced with equivalent Lake Hadley through cols between drumlins in the Connecticut Valley Lowland. Deglaciation of the Belchertown quadrangle probably occurred in a span of about 100 years in the interval 12,000 to 12,500 years B.P. Unconsolidated sediments of the Belchertown quadrangle are summarized as to their geologic and geotechnical properties for land use planning. Drift as it influences groundwater flow, yield, and quality and as a construction material is assessed. Some environmental degradation has occurred from the indiscriminant disposal of liquid and solid waste as well as injudicious use of road salt.

Open-File Report↗

USGS1971

Prospects for developing stock - Water supplies from wells in northeastern Garfield County, Montana

Ground-water resources in northeastern Garfield County, Mont., afford a practical and reliable source of stock water on the intermingled public and private grazing lands that together comprise an area of about 1,200 square miles. The oldest formation exposed in the area is the relatively thick and impermeable Bearpaw Shale of Cretaceous .age. Overlying the Bearpaw Shale in succession are the Fox Hills Sandstone and Hell Creek Formation of Cretaceous age, the Fort Union Formation of Tertiary age, and thin glacial deposits .and alluvium of Quaternary age. All but the Bearpaw Shale and the glacial deposits are potential aquifers. Published geologic maps were found to be satisfactory after fitting contacts to the topographic base. Mapping, therefore, was limited mainly to outlining on aerial photographs the alluvial deposits in the stream valleys. The major structural feature is the Blood Creek syncline, the axis of which plunges eastward 10-15 feet per mile across the southern part of the area. Beds generally dip 15-25 feet per mile toward the synclinal axis. Water in bedrock aquifers is under artesian pressure, .and most wells in Big and Little Dry Creek valleys flow at the land surface. The only bedrock aquifer having appreciable areal extent is a sandstone 30-70 feet thick that has been mapped by previous investigators as the upper part of the Fox Hills Sandstone. This aquifer crops out in the northern and northwestern parts of the area and dips about 20 feet per mile southeastward beneath younger beds. Most wells in the northern half of the area obtain water from this sandstone at drilling depths of less than 200 feet. The depth to the Fox Hills Sandstone increases progressively southward, and most wells south of Woody Creek obtain water from irregularly distributed sandstone beds and lenses in the overlying Hell Creek and Fort Union Formations. The depth at which water may be obtained from these beds is not accurately predictable, but the depth seldom exceeds 300 feet. The results of the investigation indicate that the prospects for obtaining ample water for livestock from wells drilled into the bedrock formations are very favorable in most of the area. The average depth of bedrock wells in the area is 195 feet. Underflow in the alluvial deposits along all the larger stream valleys also affords a practical source of stock water. Chemical analyses of samples collected at 43 wells and three springs show the water quality to be generally poor. Water from bedrock aquifer contains 530-5,340 milligrams per liter total dissolved solids, whereas water from alluvium contains less than 1,500 milligrams per liter total dissolved solids. The predominant constituents are sodium, bicarbonate, and sulfate. So far as could be determined, all water supplies in the area are suitable for livestock.

Montana↗

USGS2010

Geology, geochemistry, and genesis of the Greens Creek massive sulfide deposit, Admiralty Island, southeastern Alaska

In 1996, a memorandum of understanding was signed by representatives of the U.S. Geological Survey and Kennecott Greens Creek Mining Company to initiate a cooperative applied research project focused on the Greens Creek massive sulfide deposit in southeastern Alaska. The goals of the project were consistent with the mandate of the U.S. Geological Survey Mineral Resources Program to maintain a leading role in national mineral deposits research and with the need of Kennecott Greens Creek Mining Company to further development of the Greens Creek deposit and similar deposits in Alaska and elsewhere. The memorandum enumerated four main research priorities: (1) characterization of protoliths for the wall rocks, and elucidation of their alteration histories, (2) determination of the ore mineralogy and paragenesis, including metal residences and metal zonation within the deposit, (3) determination of the ages of events important to ore formation using both geochronology and paleontology, and (4) development of computer models that would allow the deposit and its host rocks to be examined in detail in three dimensions. The work was carried out by numerous scientists of diverse expertise over a period of several years. The written results, which are contained in this Professional Paper, are presented by 21 authors: 13 from the U.S. Geological Survey, 4 from Kennecott Greens Creek Mining Company, 2 from academia, and 2 from consultants. The Greens Creek deposit (global resource of 24.2 million tons at an average grade of 13.9 percent zinc, 5.1 percent lead, 0.15 troy ounce per ton gold, and 19.2 troy ounces per ton silver at zero cutoff) formed in latest Triassic time during a brief period of rifting of the Alexander terrane. The deposit exhibits a range of syngenetic, diagenetic, and epigenetic features that are typical of volcanogenic (VMS), sedimentary exhalative (SEDEX), and Mississippi Valley-type (MVT) genetic models. In the earliest stages of rifting, formation of precious-metal-rich silica-barite-carbonate white ores began at low temperature in a shallow, subaqueous setting, probably a thin carbonate shelf on the flanks of the Alexander landmass. Epigenetic carbonate replacement textures in the footwall dolostones are overlain by stratiform silica-carbonate-barite-rich ores and indicate that early mineralization formed at and just beneath the paleo sea floor by mixing of a reduced, precious-metal-rich, base-metal-poor hydrothermal fluid with oxygenated seawater. As rifting intensified, the shelf was downfaulted and isolated as a graben. Isolation of the basin and onset of starved-basin shale sedimentation was concurrent with emplacement of mafic-ultramafic intrusives at shallow levels in the rift, resulting in an increasingly higher temperature and progressively more anoxic ore-forming environment. The formation of the main stage of massive sulfide ores began as the supply of bacterially reduced sulfur increased in the accumulating shales. As the main-stage mineralization intensified, shale sedimentation inundated the hydrothermal system, eventually forming a cap. Biogenic sulfate reduction supplied reduced sulfur to the base of the shales where mixing occurred with hot, base-metal-rich hydrothermal fluids. Ore deposition continued by destruction and epigenetic replacement of the early white ores in proximal areas and by inflation and diagenetic replacement of unlithified shale at the interface between the white ores and the base of the shale cap. Ore deposition waned as the shales became lithified and as the supply of bacterially reduced sulfur to the site of ore deposition ceased. The final stages of rifting resulted in the emplacement of mafic-ultramafic intrusive rocks into the Greens Creek system and extrusion of voluminous basaltic flows at the top of the Triassic section. Greenschist facies metamorphism during the Jurassic-Cretaceous accretion of the Alexander terrane to the continental margin resulted in recrystalli

Professional Paper↗

USGS1978

Progress toward a ground-water-quality monitoring network for Idaho

A ground-water-quality monitoring network is being designed for Idaho. The primary objectives of the network are to (1) determine the present quality of the State's ground water, (2) provide continual monitoring of groundwater quality for water-management purposes, and (3) serve as a warning system of undesirable changes in ground-water quality. Data are compiled for geohydrologic conditions, groundwater quality, cultural elements, and pollution sources. A "Hydrologic Unit Priority Index" is calculated from these data to select priority areas for monitoring purposes. New ground-water-quality data were collected where existing data were lacking and at some sites that were previously sampled. Old and new data at common sites correlated well, indicating that the water quality has not changed significantly. Most ground water in Idaho is of good quality for common uses; however, water quality may pose problems in local areas. The problems result from both natural and human causes. The potential for pollution of the aquifers is expected to be greatest in areas of greatest development. In Idaho, population centers and industries tend to be in areas of privately owned irrigated and arable · land. Therefore, these areas are of primary concern for monitoring ground-water quality. Other areas requiring monitoring include those with second-home development, mining and its related processes, and radioactive-waste disposal.

Idaho↗

USGS2014

Technical implementation plan for the ShakeAlert production system: an Earthquake Early Warning system for the West Coast of the United States

Earthquake Early Warning (EEW) systems can provide as much as tens of seconds of warning to people and automated systems before strong shaking arrives. The United States Geological Survey (USGS) and its partners are developing such an EEW system, called ShakeAlert, for the West Coast of the United States. This document describes the technical implementation of that system, which leverages existing stations and infrastructure of the Advanced National Seismic System (ANSS) regional networks to achieve this new capability. While significant progress has been made in developing the ShakeAlert early warning system, improved robustness of each component of the system and additional testing and certification are needed for the system to be reliable enough to issue public alerts. Major components of the system include dense networks of ground motion sensors, telecommunications from those sensors to central processing systems, algorithms for event detection and alert creation, and distribution systems to alert users. Capital investment costs for a West Coast EEW system are projected to be $38.3M, with additional annual maintenance and operations totaling $16.1M—in addition to current ANSS expenditures for earthquake monitoring. An EEW system is complementary to, but does not replace, other strategies to mitigate earthquake losses. The system has limitations: false and missed alerts are possible, and the area very near to an earthquake epicenter may receive little or no warning. However, such an EEW system would save lives, reduce injuries and damage, and improve community resilience by reducing longer-term economic losses for both public and private entities.

California;Oregon;Washington↗

USGS1977

Municipal water supplies in Lee County, Florida, 1974

In response to population growth, demands for water in Lee County have increased markedly in the past 5 years. In 1974, the 10 largest municipal water-supply systems in the county supplied the water needs of about 170,000 people. Ongoing water-resources investigations are aimed at providing responsible and interested parties with the necessary information to effectively manage and utilize the water resources of Lee County. Raw freshwater is supplied to the municipal water plants from the Caloosahatchee River and from three ground-water sources: the watertable aquifer, the uppermost part of the Tamiami Formation and the upper part of the Hawthorn Formation. Saline water, which is used after desalting, is supplied from two permeable zones, one in the lower part of the Hawthorn Formation and the other in the Suwannee Limestone. The total quantity of raw water pumped during 1974 was 5,700 million gallons, an increase of 54 percent from 1970 pumpage. The largest source of supply in use is the water-table aquifer and the smallest are the lower part of the Hawthorn Formation and the Suwannee Limestone. Increased pumping from the upper part of the Hawthorn for public supply and irrigation has resulted in progressively declining water levels, an indication that the supply of water from this source is limited. After expansion of the Sanibel Island and Cape Coral water-supply systems, increasing demands will be placed on the water-bearing stratum in the lower part of the Hawthorn Formation and the Suwannee Limestone. At the present time (1976), there is limited information on the quantity and quality of water available in these saline-water-bearing strata beneath Lee County. The quality of fresh ground water in areas unaffected by intrusion of saline water, generally meets all the recommended limits of the Environmental Protection Agency. The chemical treatment processes utilized by water water plants in the county are generally effective in producing finished water that meets EPA preliminary drinking water standards. The rapid increase in water demands over the last 5 years, together with an anticipated accelerated demand in the future, indicates a necessity for expanding the knowledge of the water resources of the county. Specifically, additional efforts will be required to determine the yield characteristics of and quality of water in each of the groundwater sources in Lee County.

Florida↗

USGS2007

Historical changes in the Mississippi-Alabama barrier islands and the roles of extreme storms, sea level, and human activities

An historical analysis of images and documents shows that the Mississippi-Alabama (MS-AL) barrier islands are undergoing rapid land loss and translocation. The barrier island chain formed and grew at a time when there was a surplus of sand in the alongshore sediment transport system, a condition that no longer prevails. The islands, except Cat, display alternating wide and marrow segments. Wide segments generally were products of low rates of inlet migration and spit elongation that resulted in well-defined ridges and swales formed by wave refraction along the inlet margins. In contrast, rapid rates of inlet migration and spit elongation under conditions of surplus sand produced low, narrow, straight barrier segments. Since the mid 1800s, average rates of land loss for all the MS islands accelerated systematically while maintaining consistency from island to island. In contrast, Dauphin Island, off the Alabama coast, gained land during the early 20th century and then began to lose land at rates comparable to those of the MS barriers. There is an inverse relationship between island size and percentage of land reduction for each barrier such that Horn Island lost 24% and Ship Island lost 64% of its area since the mid 1800s. Ship Island is particularly vulnerable to storm-driven land losses because topographic and bathymetric boundary conditions focus wave energy onto the island. The three predominant morphodynamic processes associated with land loss are: (1) unequal lateral transfer of sand related to greater updrift erosion compared to downdrift deposition, (2) barrier narrowing resulting from simultaneous erosion of the Gulf and Soundside shores, and (3) barrier segmentation related to storm breaching. The western three fourths of Dauphin Island are migrating landward as a result of storms that erode the Gulf shore, overwash the island, and deposit sand in Mississippi Sound. Petit Bois, Horn, and Ship Islands have migrated westward as a result of predominant westward sediment transport by alongshore currents, and Cat Island is being reshaped as it adjusts to post-formation changes in wave and current patterns associated with deposition of the St. Bernard lobe of the Mississippi delta. The principal causes of barrier island land loss are frequent intense storms, a relative rise in sea level, and a deficit in the sediment budget. The only factor that has a historical trend that coincides with the progressive increase in rates of land loss is the progressive reduction in sand supply associated with nearly simultaneous deepening of channels dredged across the outer bars of the three tidal inlets maintained for deep-draft shipping. Neither rates of relative sea level rise nor storm parameters have long-term historical rends that match the increased rates of land loss since the mid 1800s. The historical rates of relative sea level rise in the northern Gulf of Mexico have been relatively constant and storm frequencies and intensities occur in multidecal cycles. However, the most recent land loss accelerations likely related to the increased storm activity since 1995. Considering the predicted trends for storms and sea level related to global warming, it is clear that the barrier islands will continue to lose land area at a rapid rate without a reversal in trend of at least one of the causal factors. The reduction in sand supply related to disruption of the alongshore sediment transport system is the only factor contributing to land loss that can be managed directly. This can be accomplished by placing dredged material so that the adjacent barrier island shores revive it for island nourishment and rebuilding.

Alabama;Mississippi↗

USGS2009

Natural offshore oil seepage and related tarball accumulation on the California coastline — Santa Barbara Channel and the southern Santa Maria Basin; source identification and inventory

Oil spillage from natural sources is very common in the waters of southern California. Active oil extraction and shipping is occurring concurrently within the region and it is of great interest to resource managers to be able to distinguish between natural seepage and anthropogenic oil spillage. The major goal of this study was to establish the geologic setting, sources, and ultimate dispersal of natural oil seeps in the offshore southern Santa Maria Basin and Santa Barbara Basins. Our surveys focused on likely areas of hydrocarbon seepage that are known to occur between Point Arguello and Ventura, California. Our approach was to 1) document the locations and geochemically fingerprint natural seep oils or tar; 2) geochemically fingerprint coastal tar residues and potential tar sources in this region, both onshore and offshore; 3) establish chemical correlations between offshore active seeps and coastal residues thus linking seep sources to oil residues; 4) measure the rate of natural seepage of individual seeps and attempt to assess regional natural oil and gas seepage rates; and 5) interpret the petroleum system history for the natural seeps. To document the location of sub-sea oil seeps, we first looked into previous studies within and near our survey area. We measured the concentration of methane gas in the water column in areas of reported seepage and found numerous gas plumes and measured high concentrations of methane in the water column. The result of this work showed that the seeps were widely distributed between Point Conception east to the vicinity of Coal Oil Point, and that they by in large occur within the 3-mile limit of California State waters. Subsequent cruises used sidescan and high resolution seismic to map the seafloor, from just south of Point Arguello, east to near Gaviota, California. The results of the methane survey guided the exploration of the area west of Point Conception east to Gaviota using a combination of seismic instruments. The seafloor was mapped by sidescan sonar, and numerous lines of high -resolution seismic surveys were conducted over areas of interest. Biomarker and stable carbon isotope ratios were used to infer the age, lithology, organic matter input, and depositional environment of the source rocks for 388 samples of produced crude oil, seep oil, and tarballs mainly from coastal California. These samples were used to construct a chemometric fingerprint (multivariate statistics) decision tree to classify 288 additional samples, including tarballs of unknown origin collected from Monterey and San Mateo County beaches after a storm in early 2007. A subset of 9 of 23 active offshore platform oils and one inactive platform oil representing a few oil reservoirs from the western Santa Barbara Channel were used in this analysis, and thus this model is not comprehensive and the findings are not conclusive. The platform oils included in this study are from west to east: Irene, Hildago, Harvest, Hermosa, Heritage, Harmony, Hondo, Holly, Platform A, and Hilda (now removed). The results identify three “tribes” of 13 C-rich oil samples inferred to originate from thermally mature equivalents of the clayey-siliceous, carbonaceous marl, and lower calcareous-siliceous members of the Monterey Formation. Tribe 1 contains four oil families having geochemical traits of clay-rich marine shale source rock deposited under suboxic conditions with substantial higher-plant input. Tribe 2 contains four oil families with intermediate traits, except for abundant 28,30-bisnorhopane, indicating suboxic to anoxic marine marl source rock with hemipelagic input. Tribe 3 contains five oil families with traits of distal marine carbonate source rock deposited under anoxic conditions with pelagic but little or no higher-plant input. Tribes 1 and 2 occur mainly south of Point Conception in paleogeographic settings where deep burial of the Monterey Formation source rock favored generation from all three members or their equivalents. In this area, oil from the clayey-siliceous and carbonaceous marl members (Tribes 1 and 2) may overwhelm that from the lower calcareous-siliceous member (Tribe 3) because the latter is thinner and less oil-prone than the overlying members. Tribe 3 occurs mainly north of Point Conception, where shallow burial caused preferential generation from the underlying lower calcareous-siliceous member or another unit with similar characteristics. It is very desirable to be able to clearly distinguish the naturally occurring seep oils from the anthropogenically derived platform oils. Within the “training set” of oils and tars (388 samples), the biomarker parameters are sometimes sufficient to allow unique discrimination of individual platform oils. More often however, platform samples and seep samples with sources geographically close to each other are too similar to each other, with respect to the biomarker parameters, to definitively differentiate them on that basis alone. In some cases other parameters can be helpful. These other parameters are related to the degree of biogeochemical degradation or weathering that the oils or tars have experienced. These components include the typical oil distribution of n-alkane hydrocarbons and isoprenoids pristane and phytane. All of the platform oils in our sample set contain these components. On the other hand, the seep oils or tars have been exposed to significant biodegradation while in the near subsurface. The majority, but not all of seep oils or tars have been biodegraded up to or beyond the loss of n-alkanes and isoprenoids. Seep oils found in the vicinity of Coal Oil Point or Arroyo Burro are apparently the least weathered and are particularly likely to retain significant n-alkanes and isoprenoids. Therefore the combination of chemometric fingerprinting and the presence or absence of n-alkanes and isoprenoids help to differentiate anthropogenic production oils versus natural seeps oils and tars. The differentiation is not always definitive because of the close chemical similarity of some samples and the variability in the biodegradation progression. This is the case near Coal Oil Point, and near Platform A (Dos Cuadros Field) where seep oils and Platform Holly and Platform A oils are genetically very similar and cannot be definitively distinguished after a period of a few days of weathering. In contrast, oils from the Point Conception platforms can be distinguished on the basis of chemometric fingerprinting alone. In the middle of this spectrum are oils from Platforms Harmony, Heritage, and Hondo, where it is expected that oil weathering would take on the order of two weeks to a month to produce tarballs similar to those seen near Point Conception. In this case there is a much greater degree of weathering needed to proceed from produced oil to the biodegraded tar characteristic of tarball stranded on the beach. Tar deposition on beaches was monitored as part of cooperative with the County of Santa Barbara Energy Division and the U.S. Geological Survey during 2001-2003. We found tar deposition varies on a seasonal basis. In general, tarballs accumulate at a faster rate or remain longer on all beaches during the summer and fall months. The reasons for this are unclear based on our limited observations, however we speculate that factors such as prevailing winds and currents combined with more quiescent wave conditions favors the accumulation and preservation of tarballs on the beach during the summer and fall months. In contrast, winter storms, with much greater wave action remove beach sand and other materials, and stormy seas tend to break up oil that might weather into tarballs. Natural seepage is affected by the spring/neap tidal cycle; however, the link to tar deposition is unclear. Longer periods of monitoring are needed to address the variability in the data and provide a more robust statistical analysis.

California↗

USGS1981

Geology of the Jabal Al Qarah Quadrangle, Sheet 20/43 C, Kingdom of Saudi Arabia

The Jabal al Qarah quadrangle (sheet 20/43 C) is a 30-minute quadrangle mapped at 1:100,000 scale in the southern Najd Province of Saudi Arabia. The quadrangle is located between lat 20°00'N. and 20°30'N. and long 43°00'E. and 43°30'E. It is underlain by volcanic, volcaniclastic, and plutonic rocks of late Precambrian age. Most of the quadrangle consists of a large, asymmetric gneiss dome that extends far to the north and south of the quadrangle. Parallel with the eastern border of the quadrangle, part of the extensive, serpentinite-bearing, Nabitah fault zone probably represents a major suture between crust of Jiddah age to the west and younger crust of Halaban age to the east. An excellent section of the Halaban-age crust is exposed in and adjacent to the gneiss dome. At the eroded top of the section to the east, calc-alkalic volcanic rocks of the Halaban group are dominantly andesite but range from basalt to dacite. Beneath the volcanic rocks, comagmatic, subvolcanic plutonic rocks include predominantly diorites but range from gabbro to trondhjemite. These rocks were formed during island-arc volcanism and plutonism from about 780 m.y. to 720(?) m.y. ago. About 725 m.y. ago this primitive crust was thickened by emplacement of large intermediate-crustal depth plutons of hornblende tonalite and hornblende granodiorite. Compressional tectonism produced folds and faults with northern trends and accompanying greenschist metamorphism. Granitic plutonism began 625 m.y. ago, perhaps in response to a major continental collision between the Halaban crust and a continental mass to the east. Granodiorite-monzogranite comprising the Wadi Musayrah batholith formed the core of the Jabal al Qarah gneiss dome as the dome rose. The low-density, intermediate-depth, plutonic rocks of the Halaban crust were converted to orthogneisses as they rose. Strong compression resulted in a large west-directed thrust, the Nabitah fault zone, containing serpentinite. Subsequently, plutons of monzogranite, syenogranite, and alkali-feldspar granite intruded the eroding crust at progressively shallower levels until about 600 m.y. ago. After this time the polymictic conglomerate of the Murdama group was deposited over the youngest granite--the alkali-feldspar granite at Jabal ash Shawhatah al Hamrah; the conglomerate was subsequently deformed. Continued compression of the now relatively thick continental crust resulted in the Najd faulting event about 570 m.y. ago. Two northwest-trending faults in the quadrangle have left-lateral displacement; one has 7 km of offset. These two faults are small but are characteristic of the large Najd fault zones farther north. Throughout the quadrangle, northwest-trending Najd fracturing was pervasive and many of these secondary fractures were filled with diabase dikes of Najd age. The diabase dikes and the deeper, non-exposed mafic plutons induced small-scale, but widespread hydrothermal convection and alteration that produced small quartz veins locally mineralized with gold. Quartz-vein gold was mined on a small scale by ancient miners in several areas. An extensive gold placer was worked about 2,600 years ago in a 50 km 2 area at Jabal Mokhyat. None of these deposits are economical by present-day standards.

Jabal Al Qarah Quadrangle↗

USGS1983

The compositionally zoned eruption of 1912 in the Valley of Ten Thousand Smokes, Katmai National Park, Alaska

On June 6–8, 1912, ∼ 15 km 3 of magma erupted from the Novarupta caldera at the head of the Valley of Ten Thousand Smokes (VTTS), producing ∼ 20 km 3 of air-fall tephra and 11–15 km 3 of ash-flow tuff within ∼ 60 hours. Three discrete periods of ash-fall at Kodiak correlate, respectively, with Plinian tephra layers designated A, CD, and FG by Curtis (1968) in the VTTS. The ash-flow sequence overlapped with but outlasted pumice fall A, terminating within 20 hours of the initial outbreak and prior to pumice fall C. Layers E and H consist mostly of vitric dust that settled during lulls, and Layer B is the feather edge of the ash flow. The fall units filled and obscured the caldera, but arcuate and radial fissures outline a 6-km 2 depression. The Novarupta lava dome and its ejecta ring were emplaced later within the depression. At Mt. Katmai, 10 km east of the 1912 vent, a 600-m-deep caldera of similar area also collapsed at about this time, probably owing to hydraulic connection with the venting magma system; but all known ejecta are thought to have erupted at Novarupta. Mingling of three distinctive magmas during the eruption produced an abundance of banded pumice, and mechanical mixing of chilled ejecta resulted in deposits with a wide range of bulk composition. Pumice in the initial fall unit (A) is 100% rhyolite, but fall units atop the ash flow are > 98% dacite; black andesitic scoria is common only in the ash flows and in near-vent air-fall tephra. Pumice counts show the first half of the ash-flow deposit to be 91–98% rhyolite, but progressive increases of dacite and andesite eventually reduced the rhyolitic component to < 2%. The later, rhyolite-poor flows were hotter, less mobile, and widely produced partially welded tuff and vapor-indurated sillar. The main ash flow was too deflated and sluggish 16 km from the vent to surmount a 25-m-high moraine in its path but was diverted around it and continued 5 km down-valley, engulfing and charring trees but not toppling all of them. Thin ash-flow veneers feather 30–40 m up the enclosing valley walls but only where a constriction in the central VTTS locally raised the flow level. In the upper VTTS, the “high sand mark” is not a veneer but a marginal bench formed in thick tuff by differential compaction. Flooding from adjacent glaciers led to phreatic explosions that ejected blocks of tuff more welded than any yet exposed. A cluster of phreatic craters dammed a lake atop the tuff, the breaching of which caused a flood that scoured the ash-flow surface in the central VTTS, transported 50-cm blocks of welded tuff > 20 km to the lowermost VTTS, and deposited 1–8 m of debris there. Rhyolitic ejecta contain only 1–2% phenocrysts but andesite and dacite have 30–45%. Quartz is present and augite absent only in the rhyolite, but all ejecta contain plagioclase, orthopyroxene, titanomagnetite, ilmenite, apatite, and pyrrhotite; rare olivine occurs in the andesite. The zoning ranges of phenocrysts in the rhyolitic and intermediate ejecta do not overlap. New chemical data show the bulk SiO 2 range to be: rhyolite 77 ± 0.6, dacite 66-64.5, and andesite 61.5–58.5%. The dacitic and andesitic ejecta contrast in color and density, and it is not certain whether they form a compositional continuum. Analyses reported by Fenner within the 66–76% SiO 2 range were of banded pumice and lava and of bulk tephra that mechanically fractionated and mixed during flight. Despite the gap of 10% SiO 2 , Fe-Ti-oxide temperatures show a continuous range from rhyolite (805–850°C) through dacite (855–955°C) to andesite (955–990°C). Thermal continuity and isotopic and trace-element data suggest that all were derived from a single magmatic system, whether or not they were physically contiguous before eruption. If the rhyolitic liquid separated from dacitic magma, extraction was so efficient that no dacitic phenocrysts were retained and no bulk compositions in the range 66–76% SiO 2 were created; if it were a partial melt of roof rocks atop an intermediate magma body, then such rocks had no O- or Sr-isotopic contrast with the andesite-dacite magma and clearly did not include the Jurassic arkosic or granitic basement. The presence of Holocene domes of pre-1912 glassy dacite adjacent to the 1912 vent suggest that the 7 km 3 (or more) of high-silica rhyolitic magma (a composition rare in the Aleutian arc) was generated in less than a few thousand years. The 1912 vent is semi-encircled by several andesitic stratocones and is as close to Mageik, Trident, and Griggs volcanoes as it is to Mt. Katmai. The erupted magma probably occupied only shallow levels of an extensive system of injection and storage under a cluster of several stratovolcanoes. Although Quaternary basalt is not known to have erupted here, the intrusion of basaltic magma probably sustains the greater-VTTS magmatic system.

Alaska↗

USGS2008

Mapping of Florida's coastal and marine resources: Setting priorities workshop

The importance of mapping habitats and bioregions as a means to improve resource management has become increasingly clear. Large areas of the waters surrounding Florida are unmapped or incompletely mapped, possibly hindering proper management and good decisionmaking. Mapping of these ecosystems is among the top priorities identified by the Florida Oceans and Coastal Council in their Annual Science Research Plan. However, lack of prioritization among the coastal and marine areas and lack of coordination of agency efforts impede efficient, cost–effective mapping. A workshop on Mapping of Florida’s Coastal and Marine Resources was sponsored by the U.S. Geological Survey (USGS), Florida Department of Environmental Protection (FDEP), and Southeastern Regional Partnership for Planning and Sustainability (SERPPAS). The workshop was held at the USGS Florida Integrated Science Center (FISC) in St. Petersburg, FL, on February 7-8, 2007. The workshop was designed to provide State, Federal, university, and non-governmental organizations (NGOs) the opportunity to discuss their existing data coverage and create a prioritization of areas for new mapping data in Florida. Specific goals of the workshop were multifold, including to: provide information to agencies on state-of-the-art technology for collecting data; inform participants of the ongoing mapping programs in waters off Florida; present the mapping needs and priorities of the State and Federal agencies and entities operating in Florida; work with State of Florida agencies to establish an overall priority for areas needing mapping; initiate discussion of a unified classification of habitat and bioregions; discuss and examine the need to standardize terminology and data collection/storage so that data, in particular habitat data, can be shared; identify opportunities for partnering and leveraging mapping efforts among agencies and entities; identify impediments and organizational gaps that hinder collection of data for mapping; seek innovative solutions to the primary obstacles identified; identify the steps needed to move mapping of Florida’s oceans and coasts forward, in preparation for a better coordinated, more cost-effective mapping program to allow State and Federal agencies to make better decisions on coastal-resource issues. Over 90 invited participants representing more than 30 State and Federal agencies, universities, NGOs, and private industries played a large role in the success of this two-day workshop. State of Florida agency participants created a ranked priority order for mapping 13 different regions around Florida. The data needed for each of the 13 priority regions were outlined. A matrix considering State and Federal priorities was created, utilizing input from all agencies. The matrix showed overlapping interests of the entities and will allow for partnering and leveraging of resources. The five most basic mapping needs were determined to be bathymetry, high-vertical resolution coastline for sea-level rise scenarios, shoreline change, subsurface geology, and benthic habitats at sufficient scale. There was a clear convergence on the need to coordinate mapping activities around the state. Suggestions for coordination included: creating a glossary of terms: a standard for specifying agency data-mapping needs; creating a geographic information officer (GIO) position or permanent organizing group to maintain communications established at this workshop and to maintain progress on the issues identified during the workshop. The person or group could develop a website, maintain a project-status matrix, develop a list of contacts, create links to legislative updates and links to funding sources; developing a web portal and one-stop/clearinghouse of data. There was general consensus on the need to adopt a single habitat classification system and a strategy to accommodate existing systems smoothly. Unresolved aspects of the systems warrant that a separate workshop would be needed to work out details. Participants recognized that the State priority list would necessarily be updated periodically. An annual review of priorities would facilitate information exchange, mapping activities updates, and re-allocation of funding among changing priorities. It was recognized that mapping of State waters would take billions of dollars and in light of tightening budgets there was need for processes that could be used to appropriate or leverage monies for mapping and reduce data-collection costs. Fourteen different avenues were explored. There was a clear consensus that the linking of public to private partnerships to support mapping was imperative, and ways to achieve this were discussed.

Florida↗

USGS1986

Artesian pressures and water quality in Paleozoic aquifers in the Ten Sleep area of the Bighorn Basin, north-central Wyoming

The major Paleozoic artesian aquifers, the aquifers most favorable for continued development, in the Ten Sleep area of the Bighorn Basin of Wyoming are the Tensleep Sandstone, the Madison Limestone and Bighorn Dolomite (Madison-Bighorn aquifer), and the Flathead Sandstone. The minor aquifers include the Goose Egg and Park City Formations (considered in the Ten Sleep area to be the lateral equivalent of the Phosphoria Formation) and the Amsden Formation. Most wells completed in the major and minor aquifers flow at the land surface. Wellhead pressures generally are less than 50 pounds per square inch for the Tensleep Sandstone, 150-250 pounds per square inch for the Madison-Bighorn aquifer, and more than 400 pounds per square inch for the Flathead Sandstone. Flowing wells completed in the Madison-Bighorn aquifer and the Flathead Sandstone yield more than 1,000 gallons per minute. The initial test of one well completed in the Madison-Bighorn aquifer indicated a flow rate of 14,000 gallons per minute. Transmissivities range from 500 to 1,900 feet squared per day for the Madison-Bighorn aquifer and from about 90 to 325 feet squared per day for the Tensleep and Flathead Sandstones. Significant secondary permeability from fracturing in the Paleozoic aquifers allows local upward interformational movement of water, and this affects the altitude of the potentiometric surfaces of the Tensleep Sandstone and the Madison-Bighorn aquifer. Water moves upward from the Tensleep and other formations, through the Goose Egg Formation, to discharge at the land surface as springs. Much of the spring flow is diverted for irrigation or is used for rearing fish. Decreases from original well pressures were not apparent in wells completed in the Tensleep Sandstone or in the Madison-Bighorn aquifer in the study area except for a few wells in or near the town of Ten Sleep. Most wells completed in the Flathead Sandstone, which also are open to the Madison-Bighorn aquifer, show a decrease of pressure from the time of completion to 1978. The decrease of pressure is partly the result of water moving from the Flathead Sandstone into the Madison-Bighorn aquifer, which has a lower potentiometric surface than does the Flathead Sandstone, even during the time the wells are not in operation. Pressure in some small-capacity wells completed in the Goose Egg Formation also has decreased near Ten Sleep. Most of the wells, particularly the irrigation wells, show a progressive decrease in pressure during the irrigation season but recover during periods of nonuse. Measurements of the pressure were made principally in 1953, 1962, 1970, and 1975-78. Well water from the Paleozoic aquifers generally contains minimal concentrations of dissolved solids and individual constituents but excessive hardness. Dissolved-solids concentrations of water are less than 300 milligrams per liter in the Tensleep Sandstone and the Madison-Bighorn aquifer, less than 200 milligrams per liter in the Flathead Sandstone, and as much as 450 milligrams per liter in the Goose Egg Formation. Bicarbonate is the major constituent, followed by calcium and magnesium. Relatively large concentrations of sulfate, as much as 490 milligrams per liter, were found, mainly in water from the Goose Egg Formation. The water has low sodium (alkali) and medium salinity; therefore, the water is satisfactory for irrigation and most other uses, if excessive hardness is not a detrimental factor. Wellhead temperatures range from 11 ? to 27.5 ? Celsius (51 ? to 81.5 ? Fahrenheit) within a range in depth of approximately 250 to 4,000 feet. This gives a geothermal gradient of about 0.44 ? Celsius per 100 feet (0.79 ? Fahrenheit per 100 feet).

Water Supply Paper↗

USGS2016

Concentration, flux, and trend estimates with uncertainty for nutrients, chloride, and total suspended solids in tributaries of Lake Champlain, 1990–2014

The U.S. Geological Survey, in cooperation with the New England Interstate Water Pollution Control Commission and the Vermont Department of Environmental Conservation, estimated daily and 9-month concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids from 1990 (or first available date) through 2014 for 18 tributaries of Lake Champlain. Estimates of concentration and flux, provided separately in Medalie (2016), were made by using the Weighted Regressions on Time, Discharge, and Season (WRTDS) regression model and update previously published WRTDS model results with recent data. Assessment of progress towards meeting phosphorus-reduction goals outlined in the Lake Champlain management plan relies on annual estimates of phosphorus flux. The percent change in annual concentration and flux is provided for two time periods. The R package EGRETci was used to estimate the uncertainty of the trend estimate. Differences in model specification and function between this study and previous studies that used WRTDS to estimate concentration and flux using data from Lake Champlain tributaries are described. Winter data were too sparse and nonrepresentative to use for estimates of concentration and flux but were sufficient for estimating the percentage of total annual flux over the period of record. Median winter-to-annual fractions ranged between 21 percent for total suspended solids and 27 percent for dissolved phosphorus. The winter contribution was largest for all constituents from the Mettawee River and smallest from the Ausable River. For the full record (1991 through 2014 for total and dissolved phosphorus and chloride and 1993 through 2014 for nitrogen and total suspended solids), 6 tributaries had decreasing trends in concentrations of total phosphorus, and 12 had increasing trends; concentrations of dissolved phosphorus decreased in 6 and increased in 8 tributaries; fluxes of total phosphorus decreased in 5 and increased in 10 tributaries; and fluxes of dissolved phosphorus decreased in 4 and increased in 10 tributaries (where the number of increasing and decreasing trends does not add up to 18, the remainder of tributaries had no trends). Concentrations and fluxes of nitrogen decreased in 10 and increased in 4 tributaries and of chloride decreased in 2 and increased in 15 tributaries. Concentrations of total suspended solids decreased in 4 and increased in 8 tributaries, and fluxes of total suspended solids decreased in 3 and increased in 11 tributaries. Although time intervals for the percent changes from this report are not completely synchronous with those from previous studies, the numbers of and specific tributaries with overall negative percent changes in concentration and flux are similar. Concentration estimates of total phosphorus in the Winooski River were used to trace whether changes in trends between a previous study and the current study were due generally to differences in model specifications or differences from 4 years of additional data. The Winooski River analysis illustrates several things: that keeping all model specifications equal, concentration estimates increased from 2010 to 2014; the effects of a smoothing algorithm used in the current study that was not available previously; that narrowing model half-window widths increased year-to-year variations; and that the change from an annual to a 9-month basis by omitting winter estimates changed a few individual points but not the overall shape of the flow-normalized curve. Similar tests for other tributaries showed that the primary effect of differences in model specifications between the previous and current studies was perhaps to increase scatter over time but that changes in trends generally were the result of 4 years of additional data rather than artifacts of model differences.

New York, Vermont↗