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USGS2007

Initial Everglades Depth Estimation Network (EDEN) digital elevation model research and development

The Everglades Depth Estimation Network (EDEN) offers a consistent and documented dataset that can be used to guide large-scale field operations, to integrate hydrologic and ecological responses, and to support biological and ecological assessments that measure ecosystem responses to the Comprehensive Everglades Restoration Plan (Telis, 2006). To produce historic and near-real time maps of water depths, the EDEN requires a system-wide digital elevation model (DEM) of the ground surface. Accurate Everglades wetland ground surface elevation data were non-existent before the U.S. Geological Survey (USGS) undertook the collection of highly accurate surface elevations at the regional scale. These form the foundation for EDEN DEM development. This development process is iterative as additional high accuracy elevation data (HAED) are collected, water surfacing algorithms improve, and additional ground-based ancillary data become available. Models are tested using withheld HAED and independently measured water depth data, and by using DEM data in EDEN adaptive management applications. Here the collection of HAED is briefly described before the approach to DEM development and the current EDEN DEM are detailed. Finally future research directions for continued model development, testing, and refinement are provided.

Florida↗

USGS2011

Characterizing the size distribution of particles in urban stormwater by use of fixed-point sample-collection methods

The U.S Geological Survey, in cooperation with the Wisconsin Department of Natural Resources (WDNR) and in collaboration with the Root River Municipal Stormwater Permit Group monitored eight urban source areas representing six types of source areas in or near Madison, Wis. in an effort to improve characterization of particle-size distributions in urban stormwater by use of fixed-point sample collection methods. The types of source areas were parking lot, feeder street, collector street, arterial street, rooftop, and mixed use. This information can then be used by environmental managers and engineers when selecting the most appropriate control devices for the removal of solids from urban stormwater. Mixed-use and parking-lot study areas had the lowest median particle sizes (42 and 54 (u or mu)m, respectively), followed by the collector street study area (70 (u or mu)m). Both arterial street and institutional roof study areas had similar median particle sizes of approximately 95 (u or mu)m. Finally, the feeder street study area showed the largest median particle size of nearly 200 (u or mu)m. Median particle sizes measured as part of this study were somewhat comparable to those reported in previous studies from similar source areas. The majority of particle mass in four out of six source areas was silt and clay particles that are less than 32 (u or mu)m in size. Distributions of particles ranging from <2 to >500 (u or mu)m were highly variable both within and between source areas. Results of this study suggest substantial variability in data can inhibit the development of a single particle-size distribution that is representative of stormwater runoff generated from a single source area or land use. Continued development of improved sample collection methods, such as the depth-integrated sample arm, may reduce variability in particle-size distributions by mitigating the effect of sediment bias inherent with a fixed-point sampler.

Open-File Report↗

USGS2016

Collection, processing, and quality assurance of time-series electromagnetic-induction log datasets, 1995–2016, south Florida

Time-series electromagnetic-induction log (TSEMIL) datasets are collected from polyvinyl-chloride cased or uncased monitoring wells to evaluate changes in water conductivity over time. TSEMIL datasets consist of a series of individual electromagnetic-induction logs, generally collected at a frequency of once per month or once per year that have been compiled into a dataset by eliminating small uniform offsets in bulk conductivity between logs probably caused by minor variations in calibration. These offsets are removed by selecting a depth at which no changes are apparent from year to year, and by adjusting individual logs to the median of all logs at the selected depth. Generally, the selected depths are within the freshwater saturated part of the aquifer, well below the water table. TSEMIL datasets can be used to monitor changes in water conductivity throughout the full thickness of an aquifer, without the need for long open-interval wells which have, in some instances, allowed vertical water flow within the well bore that has biased water conductivity profiles. The TSEMIL dataset compilation process enhances the ability to identify small differences between logs that were otherwise obscured by the offsets. As a result of TSEMIL dataset compilation, the root mean squared error of the linear regression between bulk conductivity of the electromagnetic-induction log measurements and the chloride concentration of water samples decreased from 17.4 to 1.7 millisiemens per meter in well G–3611 and from 3.7 to 2.2 millisiemens per meter in well G–3609. The primary use of the TSEMIL datasets in south Florida is to detect temporal changes in bulk conductivity associated with saltwater intrusion in the aquifer; however, other commonly observed changes include (1) variations in bulk conductivity near the water table where water saturation of pore spaces might vary and water temperature might be more variable, and (2) dissipation of conductive water in high-porosity rock layers, which might have entered these layers during drilling. Although TSEMIL dataset processing of even a few logs improves evaluations of the differences between the logs that are related to changes in the salinity, about 16 logs are needed to estimate the bulk conductivity within ±2 millisiemens per meter. Unlike many other types of data published by the U.S. Geological Survey, the median of TSEMIL datasets should not be considered final until 16 logs are collected and the median of the dataset is stable.

Florida↗

USGS2017

Mapping the change of Phragmites australis live biomass in the lower Mississippi River Delta marshes

Multiyear remote sensing mapping of the normalized difference vegetation index (NDVI) was carried out as an indicator of live biomass composition of the Phragmites australis (hereafter Phragmites ) marsh in the lower Mississippi River Delta (hereafter delta) from 2014 to 2017. Maps of NDVI change showed that the Phragmites condition was fairly stable between May 2014 and July 2015. From July 2015 to April 2016 NDVI change indicated Phragmites suffered a widespread decline in the live biomass proportion. Between April and September 2016, most marsh remained unchanged from the earlier period or showed improvement; although there were pockets of continued decline scattered throughout the lower delta. From September 2016 to May 2017 a pronounced and widely exhibited decline in the condition of Phragmites marsh again occurred throughout the lower delta. This final NDVI change mapping supported field observations of Phragmites decline during the same period.

Louisiana↗

USGS1986

Operating manual for the miniservo-control tester

Ever since the implementation of servo-control units (regular and minimodels) with manometers at U. S. Geological Survey streamflow stations, the need for an effective and efficient servo-control unit tester has been paramount among field personnel. In numerous cases, servo-control unit failures were blamed on battery failures and vice versa. There was no valid instrument to definitively identify cause of failure, let alone properly diagnose the servo-control/manometer system. In 1983, two servo-control unit testers were developed and fabricated. One was mechanical in fabrication, operation, and serviceability; the other was electronic. The testers were extensively used and evaluated in Maine, Ohio, Kansas, and Louisiana under a wide range of environmental conditions. The consensus to integrate the best aspects of both testers into one instrument allowed the Survey to finally solve its long-time need for an effective, efficient servo-control unit tester. (USGS)

Open-File Report↗

USGS1971

Use of time-lapse photography equipment for hydrologic studies

This report describes equipment used for recording hydrologic events photographically on a controlled time scale. Equipment used included a 16-mm (millimeter) motion-picture camera, batteries, and associated intervalometer hardware. Variables that affected operation of the equipment, and which were used to turn the equipment on and off upon demand, were sunlight intensity, rainfall, and time. Winding of the camera and final shutdown were accomplished manually. A 15-minute silent motion picture was made from the time-lapse film installed at Bolinas Lagoon. This film shows sand erosion and deposition on the Stinson Beach Spit during the period January 1968 to July 1969.

Open-File Report↗

USGS2018

Smallmouth bass predation on subyearling fall Chinook salmon in Lower Granite Reservoir, 2016–2017

Predation by nonnative fishes is one factor that has been implicated in the decline of juvenile salmonids in the Pacific Northwest. Impoundment of much of the Snake and Columbia Rivers has altered food webs and created habitat favorable for species such as smallmouth bass Micropterus dolomieu. Smallmouth bass are common throughout the Columbia River basin and have become the most abundant predator in lower Snake River reservoirs (Zimmerman and Parker 1995). This is a concern for Snake River fall Chinook salmon Oncorhynchus tshawytscha (hereafter, subyearlings) that may be particularly vulnerable due to their relatively small size and because their main-stem rearing habitats often overlap or are in close proximity to habitats used by smallmouth bass (Curet 1993; Tabor et al. 1993). Concern over juvenile salmon predation spawned a number of large-scale studies to quantify its effect in the late 1980s, 1990s, and early 2000s (Poe et al. 1991; Rieman et al. 1991; Vigg et al. 1991; Fritts and Pearsons 2004; Naughton et al. 2004). Smallmouth bass predation represented 9% of total salmon consumption by predatory fishes in John Day Reservoir, Columbia River, from 1983 through 1986 (Rieman et al. 1991). In transitional habitat between the Hanford Reach of the Columbia River and McNary Reservoir, juvenile salmon (presumably subyearlings) were found in 65% of smallmouth bass (>200 mm) stomachs and comprised 59% of the diet by weight (Tabor et al. 1993). Within Lower Granite Reservoir on the Snake River, Naughton et al. (2004) showed that monthly consumption (based on weight) ranged from 5% in the upper reaches of the reservoir to 11% in the forebay. However, studies in the Snake River were conducted soon after Endangered Species Act (ESA) listing of Snake River fall Chinook salmon (NMFS 1992). During this time, fall Chinook salmon abundance was at an historic low, which may explain why consumption rates were relatively low compared to those from studies conducted in the Columbia and Yakima Rivers where abundance was higher (e.g., Tabor et al. 1993; Fritts and Pearsons 2004). We speculate that predation on subyearlings by smallmouth bass in the Snake River may have increased in recent years for several reasons. Since their ESA listing, recovery measures implemented for Snake River fall Chinook salmon have resulted in a large increase in the juvenile population (Connor et al. 2013). Considering that subyearlings probably now make up a larger portion of the forage fish population, it is plausible they should make up a larger portion of smallmouth bass diets. Second, migrating subyearlings delay downstream movement in the transition zones of the Clearwater River and Snake River for varying lengths of time (Tiffan et al. 2010), which increases their exposure and vulnerability to predators. Spatial overlap in locations of smallmouth bass and subyearlings that died during migration provides support for this (Tiffan et al. 2010). Finally, the later outmigration of subyearlings from the Clearwater River results in their presence in Lower Granite Reservoir during the warmest summer months when predation rates of smallmouth bass should be highest. In 2016 and 2017, we focused our smallmouth bass predation efforts in Lower Granite Reservoir downstream of the transition zones and the confluence area where we worked during 2012–2015. This report primarily covers results from 2017 but some results from 2016 are also included for comparison. Similar to past years, our first objective was to quantify smallmouth bass consumption rates of subyearlings, determine bass abundance, and describe bass diets. In addition, Tiffan et al. (2016a) posited that predation risk to subyearlings may be higher in shoreline habitats that are more suitable for smallmouth bass and lower in shoreline habitats that are more suitable for subyearlings. To test this hypothesis, our second objective was to examine the relationship between smallmouth bass predation and subyearling habitat suitability. Our final objective was to combine estimates of consumption with smallmouth bass abundance to derive estimates of total Chinook salmon losses to smallmouth bass for 2016 and 2017.

Idaho, Washington↗

USGS2007

A brief history of oil and gas exploration in the southern San Joaquin Valley of California:

The Golden State got its nickname from the Sierra Nevada gold that lured so many miners and settlers to the West, but California has earned much more wealth from so-called “black gold” than from metallic gold. The San Joaquin Valley has been the principal source for most of the petroleum produced in the State during the past 145 years. In attempting to assess future additions to petroleum reserves in a mature province such as the San Joaquin Basin, it helps to be mindful of the history of resource development. In this chapter we present a brief overview of the long and colorful history of petroleum exploration and development in the San Joaquin Valley. This chapter relies heavily upon the work of William Rintoul, who wrote extensively on the history of oil and gas exploration in California and especially in the San Joaquin Valley. No report on the history of oil and gas exploration in the San Joaquin Valley would be possible without heavily referencing his publications. We also made use of publications by Susan Hodgson and a U.S. Geological Survey Web site, Natural Oil and Gas Seeps in California (http://seeps.wr.usgs.gov/seeps/index.html), for much of the material describing the use of petroleum by Native Americans in the San Joaquin Valley. Finally, we wish to acknowledge the contribution of Don Arnot, who manages the photograph collection at the West Kern Oil Museum in Taft, California. The collection consists of more than 10,000 photographs that have been scanned and preserved in digital form on CD-ROM. Many of the historical photographs used in this paper are from that collection. Finally, to clarify our terminology, we use the term “San Joaquin Valley” when we refer to the geographical or topographical feature and the term “San Joaquin Basin” when we refer to geological province and the rocks therein.

California↗

USGS2016

Long-term changes in sediment and nutrient delivery from Conowingo Dam to Chesapeake Bay: Effects of reservoir sedimentation

Reduction of suspended sediment (SS), total phosphorus (TP), and total nitrogen is an important focus for Chesapeake Bay watershed management. The Susquehanna River, the bay’s largest tributary, has drawn attention because SS loads from behind Conowingo Dam (near the river’s mouth) have been rising dramatically. To better understand these changes, we evaluated histories of concentration and loading (1986–2013) using data from sites above and below Conowingo Reservoir. First, observed concentration-discharge relationships show that SS and TP concentrations at the reservoir inlet have declined under most discharges in recent decades, but without corresponding declines at the outlet, implying recently diminished reservoir trapping. Second, best estimates of mass balance suggest decreasing net deposition of SS and TP in recent decades over a wide range of discharges, with cumulative mass generally dominated by the 75&sim;99.5th percentile of daily Conowingo discharges. Finally, stationary models that better accommodate effects of riverflow variability also support the conclusion of diminished trapping of SS and TP under a range of discharges that includes those well below the literature-reported scour threshold. Overall, these findings suggest that decreased net deposition of SS and TP has occurred at subscour levels of discharge, which has significant implications for the Chesapeake Bay ecosystem.

Maryland↗

USGS2020

Molecular identification of water-extractable organic carbon from thermally heated soils: C-13 NMR and accurate mass analyses find benzene and pyridine carboxylic acids

To simulate the effects of wildfire on the combustion process in soils and their potential to leach organic compounds into streams and groundwater, mineral soil samples were heated at temperatures of 150–550 °C. Then, the soils were leached with deionized water, filtered, and analyzed for dissolved organic carbon. The water extract was concentrated by both XAD-8 and XAD-4 resins and analyzed by C-13 nuclear magnetic resonance and liquid chromatography time-of-flight mass spectrometry. Approximately 15–20% of the water-extractable organic carbon was identified as benzene dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acid isomers, commonly called BPCAs. Also identified were isomers of pyridine dicarboxylic acids and tricarboxylic acids (PCAs). The conversion of soil organic carbon to BPCAs occurs at 250 °C and reaches a maximum between 350 and 450 °C. At higher temperatures (>450 °C), the BPCA concentrations decrease, suggesting decarboxylation and conversion to carbon dioxide and water. This is the first report of BPCAs and PCAs in water-extractable organic carbon from thermally altered soil and suggest that these compounds are possible candidates for further water-quality studies in watersheds affected by wildfire. Finally, BPCAs and PCAs could contribute to the black carbon and nitrogen in seawater and are worthy of future investigation.

Environmental Science and Technology↗

USGS1987

Manmade organic compounds in the surface waters of the United States: a review of current understanding

This report reviews the occurrence and distribution of manmade organic compounds in the surface waters of the United States. On the basis of their aqueous solubilities, nonionic organic compounds partition themselves between water, dissolved organic matter, particulate organic matter, and the lipid reservoirs of aquatic organisms. Ionized organic compounds can be absorbed to sediments, thereby reducing their aqueous concentrations. Transformation processes of photolysis, hydrolysis, biodegradation, and volatilization can attenuate organic compounds, and attenuation rate commonly follow a first-order kinetic process. Eight groups of manmade organic compounds are discussed: 1. Polychlorinated biphenyls and organochlorine insecticides, 2. Carbamate and organophosphorus insecticides, 3. Herbicides, 4. Phenols, 5. Halogenated aliphatic and monocyclic aromatic hydrocarbons, 6. Phthalate esters, 7. Polychlorinated dibenzo-p-dioxins, and 8. Polycyclic aromatic hydrocarbons. For each compound group, data pertaining to use, production, and properties are presented and discussed. Processes that influence that the environmental fate of each group, as determined primarily through laboratory studies, are reviewed, and important fate processes are identified. Environmental concentrations of compounds from each group in water, biota, and sediment are given to demonstrate representative values for comparison to concentrations determined during ongoing research. Finally, where sufficient data exist, regional and temporal contamination trends in the United States are discussed.

Open-File Report↗

USGS1995

The stream-gaging program of the U.S. Geological Survey

The U.S. Geological Survey stream-gaging program provides streamflow data for a variety of purposes. The uses of streamflow data are described, and the growth of the stream-gaging program is related to legislation and the need to manage the Nation's water resources more effectively. A brief description is provided of the data-collection processes, computation of streamflow records, dissemination of data, and the nationwide evaluations of the stream-gaging program. Finally, the challenges for maintaining a viable stream-gaging program are described.

Circular↗

USGS2015

Evaluation of groundwater levels in the South Platte River alluvial aquifer, Colorado, 1953-2012, and design of initial well networks for monitoring groundwater levels

The South Platte River and underlying alluvial aquifer form an important hydrologic resource in northeastern Colorado that provides water to population centers along the Front Range and to agricultural communities across the rural plains. Water is regulated based on seniority of water rights and delivered using a network of administration structures that includes ditches, reservoirs, wells, impacted river sections, and engineered recharge areas. A recent addendum to Colorado water law enacted during 2002-2003 curtailed pumping from thousands of wells that lacked authorized augmentation plans. The restrictions in pumping were hypothesized to increase water storage in the aquifer, causing groundwater to rise near the land surface at some locations. The U.S. Geological Survey (USGS), in cooperation with the Colorado Water Conservation Board and the Colorado Water Institute, completed an assessment of 60 years (yr) of historical groundwater-level records collected from 1953 to 2012 from 1,669 wells. Relations of "high" groundwater levels, defined as depth to water from 0 to 10 feet (ft) below land surface, were compared to precipitation, river discharge, and 36 geographic and administrative attributes to identify natural and human controls in areas with shallow groundwater. Averaged per decade and over the entire aquifer, depths to groundwater varied between 24 and 32 ft over the 60-yr record. The shallowest average depth to water was identified during 1983-1992, which also recorded the highest levels of decadal precipitation. Average depth to water was greatest (32 ft) during 1953-1962 and intermediate (30 ft) in the recent decade (2003-2012) following curtailment of pumping. Between the decades 1993-2002 and 2003-2012, groundwater levels declined about 2 ft across the aquifer. In comparison, in areas where groundwater levels were within 20 ft of the land surface, observed groundwater levels rose about 0.6 ft, on average, during the same period, which demonstrated preferential rise in areas with shallow groundwater. Approximately 29 percent of water-level observations were identified as high groundwater in the South Platte River alluvial aquifer over the 60-yr record. High groundwater levels were found in 17 to 33 percent of wells examined by decade, with the largest percentages occurring over three decades from 1963 to 1992. The recent decade (2003-2012) exhibited an intermediate percentage (25 percent) of wells with high groundwater levels but also had the highest percentage (30 percent) of high groundwater observations, although results by observations were similar (26-29 percent) over three decades prior, from 1963 to 1992. Major sections of the aquifer from north of Sterling to Julesburg and areas near Greeley, La Salle, and Gilcrest were identified with the highest frequencies of high groundwater levels. Changes in groundwater levels were evaluated using Kendal line and least trimmed squares regression methods using a significance level of 0.01 and statistical power of 0.8. During 2003-2012, following curtailment of pumping, 88 percent of wells and 81 percent of subwatershed areas with significant trends in groundwater levels exhibited rising water levels. Over the complete 60-yr record, however, 66 percent of wells and 57 percent of subwatersheds with significant groundwater-level trends still showed declining water levels; rates of groundwater-level change were typically less than 0.125 ft/yr in areas near the South Platte River, with greater declines along the southern tributaries. In agreement, 58 percent of subwatersheds evaluated between 1963-1972 and 2003-2012 showed net declines in average decadal groundwater levels. More areas had groundwater decline in upgradient sections to the west and rise in downgradient sections to the east, implying a redistribution of water has occurred in some areas of the aquifer. Precipitation was identified as having the strongest statistically significant correlations to river discharge over annual and decadal periods (Pearson correlation coefficients of 0.5 and 0.8, respectively, and statistical significance defined by p-values less than 0.05). Correlation coefficients between river discharge and frequency of high groundwater levels were statistically significant at 0.4 annually and 0.6 over decadal periods, indicating that periods of high river flow were often coincident with high groundwater conditions. Over seasonal periods in five of the six decades examined, peak high groundwater levels occurred after spring runoff from July to September when administrative structures were most active. Between 1993-2002 and 2003-2012, groundwater levels rose while river discharge decreased, in part from greater reliance on surface water and curtailed pumping from wells without augmentation plans. Geographic attributes of elevation and proximity to streams and rivers showed moderate correlations to high groundwater levels in wells used for observing groundwater levels (correlation coefficients of 0.3 to 0.4). Local depressions and regional lows within the aquifer were identified as areas of potential shallow groundwater. Wells close to the river regularly indicated high groundwater levels, while those within depleted tributaries tended to have low frequencies of high groundwater levels. Some attributes of administrative structures were spatially correlated to high groundwater levels at moderate to high magnitudes (correlation coefficients of 0.3 to 0.7). The number of affected river reaches or recharge areas that surround a well where groundwater levels were observed and its distance from the nearest well field showed the strongest controls on high groundwater levels. Influences of administrative structures on groundwater levels were in some cases local over a mile or less but could extend to several miles, often manifesting as diffuse effects from multiple surrounding structures. A network of candidate monitoring wells was proposed to initiate a regional monitoring program. Consistent monitoring and analysis of groundwater levels will be needed for informed decisions to optimize beneficial use of water and to limit high groundwater levels in susceptible areas. Finalization of the network will require future field reconnaissance to assess local site conditions and discussions with State authorities.

Colorado↗

USGS1988

The importance of biological surveys in managing public lands in the western United States

Despite previous studies, incomplete knowledge of the mammalian fauna of many national parks hinders our ability to understand the consequences of either management actions of natural disasters to such preserves. Faunal losses have occurred and can be expected to continue (Newmark 1986a, 1986b). our studies in and near Dinosaur National Monument, one of the parks studied by Newmark (1986a, 1986b), have added 11 species to the known fauna. Some species have increased with human impact; other species have either disappeared or are declining. Finally, many species, which are uncommon and poorly known, may have rather specific habitat needs.

Report↗

USGS1992

Chemistry of the subalkalic silicic obsidians

Nonhydrated obsidians are quenched magmatic liquids that record in their chemical compositions details of the tectonic environment of formation and of the differentiation mechanisms that affected their subsequent evolution. This study attempts to analyze, in terms of geologic processes, the compositional variations in the subalkalic silicic obsidians (Si0 2 ≥70 percent by weight, molecular (Na 2 O+K 2 0)>Al 2 O 3 ). New major- and trace-element determinations of 241 samples and a compilation of 130 published major-element analyses are reported and interpreted. Obsidians from five different tectonic settings are recognized: (1) primitive island arcs, (2) mature island arcs, (3) continental margins, (4) continental interiors, and (5) oceanic extensional zones. Tectonomagmatic discrimination between these groups is successfully made on Nb-Ta, Nb-FeO t and Th-Hf-Ta plots, and compositional ranges and averages for each group are presented. The chemical differences between groups are related to the type of crust in which magmas were generated. With increasingly sialic (continental type) crust, the obsidians show overall enrichment in F, Be, Li, Mo, Nb, Rb, Sn, Ta, U, W, Zn, and the rare-earth elements, and depletion in Mg, Ca, Ba, Co, Sc, Sr, and Zr. They become more potassic, have higher Fe/Mg and F/Cl ratios, and lower Zr/Hf, Nb/Ta, and Th/U ratios. Higher values of total rare-earth elements are accompanied by light rare-earth-element enrichment and pronounced negative Eu anomalies. An attempt is made to link obsidian chemistry to genetic mechanlism. Two broad groups of rocks are distinguished: one generated where crystal-liquid processes dominated (CLPD types), which are the products of crustal anatexis, possibly under conditions of low halogen fugacity, ± crystal fractionation ± magma mixing; and a second group represented by rocks formed in the upper parts of large magma chambers by interplays of crystal fractionation, volatile transfer, magma mixing, and possibly various liquid-state differentiation mechanisms, or in other words a complex interaction of petrogenetic processes (CIPP types). Such rocks may also form by volatile-fluxed partial melting of the wallrocks, and subsequent mixing into the magma reservoir. Compositional ranges and averages for CLPD and CIPP obsidians are given. It is shown by analogy with well-documented, zoned ash-flow ruffs that obsidians fractionated by CIPP have very low Mg, P, Ba, and Sr contents, flat rare-earth-element patterns with extensive Eu anomalies, low K/Rb and Zr/Nb ratios, and relatively high Na 2 O/K 2 O ratios. There is, however, considerable compositional overlap between CLPD and CIPP obsidians. The effects of magma mixing, assimilation, and vapor-phase transport in producing compositional variations in the obsidians are briefly assessed. The geochemistry of the subalkalic silicic obsidians is described on an element-by-element basis, in order to provide a database for silicic magma compositions that will hopefully contribute to studies of granitic rocks. Attempts are also made to isolate the geochemical effects of tectonic environment and genetic mechanism for each element, by comparison with data from crystal-liquid equilibria-controlled systems, from ash-flow sheets zoned by CIPP, and from mixed-magma series. A final tabulation relates the complexities of obsidian geochemistry to all the tectonic and genetic variables.

Professional Paper↗

USGS1973

Cost analysis of ground-water supplies in the North Atlantic region, 1970

The cost of municipal and industrial ground water (or, more specifically, large supplies of ground water) at the wellhead in the North Atlantic Region in 1970 generally ranged from 1.5 to 5 cents per thousand gallons. Water from crystalline rocks and shale is relatively expensive. Water from sandstone is less so. Costs of water from sands and gravels in glaciated areas and from Coastal Plain sediments range from moderate to very low. In carbonate rocks costs range from low to fairly high. The cost of ground water at the wellhead is low in areas of productive aquifers, but owing to the cost of connecting pipe, costs increase significantly in multiple-well fields. In the North Atlantic Region, development of small to moderate supplies of ground water may offer favorable cost alternatives to planners, but large supplies of ground water for delivery to one point cannot generally be developed inexpensively. Well fields in the less productive aquifers may be limited by costs to 1 or 2 million gallons a day, but in the more favorable aquifers development of several tens of millions of gallons a day may be practicable and inexpensive. Cost evaluations presented cannot be applied to any one specific well or specific site because yields of wells in any one place will depend on the local geologic and hydrologic conditions; however, with such cost adjustments as may be necessary, the methodology presented should have wide applicability. Data given show the cost of water at the wellhead based on the average yield of several wells. The cost of water delivered by a well field includes costs of connecting pipe and of wells that have the yields and spacings specified. Cost of transport of water from the well field to point of consumption and possible cost of treatment are not evaluated. In the methodology employed, costs of drilling and testing, pumping equipment, engineering for the well field, amortization at 5% percent interest, maintenance, and cost of power are considered. The report includes an analysis of test drilling costs leading to a production well field. The discussion shows that test drilling is a relatively low cost item and that more than a minimum of test holes in a previously unexplored area is, above all, simple insurance in keeping down costs and may easily result in final lower costs for the system. Use of the jet drill for testing is considered short sighted and may result in higher total costs and possibly failure to discover good aquifers. Economic development of ground water supplies will depend on obtaining qualified hydrologic and engineering advice, on carrying out adequate test drilling, and on utilizing high-quality (at times, more costly) material.

Water Supply Paper↗

USGS1981

North Atlantic summary report: Outer Continental Shelf oil and gas activities in the North Atlantic and their onshore impacts: A summary report, July 1981

The leasing process for oil and gas exploration on the North Atlantic Outer Continental Shelf (OCS) began in June 1975. The first lease sale in the region (Lease Sale 42) was scheduled for January 31, 1978, by the Department of the Interior. However, the sale was delayed for 23 months by litigation before it was finally held on December 18, 1979. Of the 116 tracts offered, 63 tracts comprising 358,671 acres were leased as a result of the sale. Eight exploration plans have been submitted by five oil companies since Lease Sale 42. The plans call for exploratory drilling on 11 separate tracts in the lease sale area. The plans and the required Federal drilling permits for two blocks, Exxon's block 133 and Shell's block 410, have been approved. Exploratory drilling on these two blocks began on July 24, 1981. The review process to approve the other plans and the required OCS drilling permits is in progress. Onshore impacts resulting from OCS exploration in the North Atlantic are expected to be minimal. The same support base at Davisville, Rhode Island, used for drilling operations in the Mid-Atlantic Region is servicing North Atlantic activities. This facility has more than enough capacity and berthing space to service the level of activity expected during exploratory drilling. Moreover, support requirements for the North Atlantic are expected to supplement the declining level of support activity that has occurred for the Mid-Atlantic Region.

North Atlantic Region↗

USGS2007

Geologic Map and Map Database of Eastern Sonoma and Western Napa Counties, California

Introduction This report contains a new 1:100,000-scale geologic map, derived from a set of geologic map databases (Arc-Info coverages) containing information at 1:62,500-scale resolution, and a new description of the geologic map units and structural relations in the map area. Prepared as part of the San Francisco Bay Region Mapping Project, the study area includes the north-central part of the San Francisco Bay region, and forms the final piece of the effort to generate new, digital geologic maps and map databases for an area which includes Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma Counties. Geologic mapping in Lake County in the north-central part of the map extent was not within the scope of the Project. The map and map database integrates both previously published reports and new geologic mapping and field checking by the authors (see Sources of Data index map on the map sheet or the Arc-Info coverage eswn-so and the textfile eswn-so.txt). This report contains new ideas about the geologic structures in the map area, including the active San Andreas Fault system, as well as the geologic units and their relations. Together, the map (or map database) and the unit descriptions in this report describe the composition, distribution, and orientation of geologic materials and structures within the study area at regional scale. Regional geologic information is important for analysis of earthquake shaking, liquifaction susceptibility, landslide susceptibility, engineering materials properties, mineral resources and hazards, as well as groundwater resources and hazards. These data also assist in answering questions about the geologic history and development of the California Coast Ranges.

Scientific Investigations Map↗