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USGS1959

History of Imuruk Lake, Seward Peninsula, Alaska

A study of Imuruk Lake, a large, shallow lake in north-central Seward Peninsula, Alaska, illuminates the climatic history of northwestern Alaska and the tectonic history of central Seward Peninsula during Pleistocene and Recent time. Special interest attaches to the older lake sediments, because they contain evidence concerning the climate, fauna, and flora that existed in the vicinity of Bering Strait at a time when the Bering land bridge was open and when animal and plant populations were being exchanged between the eastern and western hemispheres. The lake is 8 miles long and less than 10 feet deep; bottom sediments consisting of reworked wind-blown silt bury a rolling bedrock topography of much greater relief. Analysis of the hydrologic regime indicates that much of the water draining into the lake is lost by evaporation; smaller quantities are lost by discharge through the outlet, the Kugruk River, and by leakage into the lava flows along the lake shore. Changes in the duration and temperature of the summer ice-free season would result in changes in the amount of water lost by evaporation and thus in appreciable changes in lake level. Imuruk Lake occupies an initial low area on basaltic lava flows of Quaternary age, but the initial low area has been modified by faulting and now lies in a poorly defined graben. Topographic evidence confirmed by study of lacustrine terraces indicates that until recently Imuruk Lake drained westward into the Noxapaga River instead of eastward into the Kugruk River. A history of repeated warping of the lake basin, on which is superimposed a history of oscillating lake level which is due to changes in climate, is recorded by three systems of abandoned shore-line features found along the shores: a warped shore cliff of probable Illinoian age, a double set of warped terraces of probable Wisconsin age, and a low, horizontal terrace of Recent age. Bones of bison, horse, and mammoth were found in peaty sediments containing many twigs but no large wood; their presence indicates that these mammals, at least, were capable of surviving in a tundra environment during cold stages of the Pleistocene epoch and at a time when the Bering land bridge was in existence nearby. The sediments filling the deeper parts of the bedrock basin of Imuruk Lake probably contain an uninterrupted pollen record that reflects vegetation changes in central Seward Peninsula beginning in middle Illinoian time and terminating a few thousand years ago. Core drilling and pollen analysis of these sediments would greatly amplify our understanding of late Pleistocene events in the vicinity of the Bering land bridge.

Alaska↗

USGS1982

Hydrology of the surficial aquifer in the Floyd River Basin, Iowa

The Floyd River basin was studied to provide water-resources Information for a typical surficial aquifer in northwest Iowa. Data collection included test drilling, water-level measurements, and chemical analyses of surface and ground water. The Floyd River basin drains 961 square miles of highly dissected to gently rolling topography. Major streams generally are flanked by flood plains underlain by uncemented sand and-gravel deposits. Most of the basin is directly underlain by glacial drift of Pleistocene age which is In turn underlain by rocks of Cretaceous age. Sand-and-gravel deposits underlying the major flood plains and in buried bedrock channels within the drift comprise the surficial aquifer. The surficial aquifer ranges from 10 to 40 feet In thickness and averages about 20 feet thick. Both unconfined and confined conditions occur in the aquifer and water levels range from 2 to 55 feet below land surface. An aquifer test conducted in the surficial aquifer where it is about 25 feet thick and is confined by an overlying low permeability bed Indicated an average hydraulic conductivity of 383 feet per day and a storage coefficient of 0.0001. The well was pumped at 650 gallons per minute for 43 hours. An observation well about 70 feet from the pumping well had a maximum drawdown of about 10 feet.

Iowa↗

USGS2010

Assessment of undiscovered conventional oil and gas resources, onshore Claiborne Group, United Statespart of the northern Gulf of Mexico Basin

The middle Eocene Claiborne Group was assessed for undiscovered conventional hydrocarbon resources using established U.S. Geological Survey assessment methodology. This work was conducted as part of a 2007 assessment of Paleogene-Neogene strata of the northern Gulf of Mexico Basin, including the United States onshore and state waters (Dubiel et al., 2007). The assessed area is within the Upper Jurassic-CretaceousTertiary composite total petroleum system, which was defined for the assessment. Source rocks for Claiborne oil accumulations are interpreted to be organic-rich, downdip, shaley facies of the Wilcox Group and the Sparta Sand of the Claiborne Group; gas accumulations may have originated from multiple sources, including the Jurassic Smackover Formation and the Haynesville and Bossier shales, the Cretaceous Eagle Ford and Pearsall (?) formations, and the Paleogene Wilcox Group and Sparta Sand. Hydrocarbon generation in the basin started prior to deposition of Claiborne sediments and is currently ongoing. Primary reservoir sandstones in the Claiborne Group include, from oldest to youngest, the Queen City Sand, Cook Mountain Formation, Sparta Sand, Yegua Formation, and the laterally equivalent Cockfield Formation. A geologic model, supported by spatial analysis of petroleum geology data, including discovered reservoir depths, thicknesses, temperatures, porosities, permeabilities, and pressures, was used to divide the Claiborne Group into seven assessment units (AUs) with three distinctive structural and depositional settings. The three structural and depositional settings are (1) stable shelf, (2) expanded fault zone, and (3) slope and basin floor; the seven AUs are (1) lower Claiborne stable-shelf gas and oil, (2) lower Claiborne expanded fault-zone gas, (3) lower Claiborne slope and basin-floor gas, (4) lower Claiborne Cane River, (5) upper Claiborne stable-shelf gas and oil, (6) upper Claiborne expanded fault-zone gas, and (7) upper Claiborne slope and basin-floor gas. Based on Monte Carlo simulation of justified input parameters, the total estimated mean undiscovered conventional hydrocarbon resources in the seven AUs combined are 52 million bbl of oil, 19.145 tcf of natural gas, and 1.205 billion bbl of natural gas liquids. This article describes the conceptual geologic model used to define the seven Claiborne AUs, the characteristics of each AU, and the justification behind the input parameters used to estimate undiscovered resources for each AU. The great bulk of undiscovered hydrocarbon resources are predicted to be nonassociated gas and natural gas liquids contained in deep (mostiy >12,000-ft [3658 m], present-day drilling depths), overpressured, structurally complex outer shelf or slope and basin-floor Claiborne reservoirs. The continuing development of these downdip objectives is expected to be the primary focus of exploration activity for the onshore middle Eocene Gulf Coast in the coming decades. ?? 2010 U.S. Geological Survey. All rights reserved.

American Association of Petroleum Geologists Bulle↗

USGS1985

Depositional Relations of Umpqua and Tyee Formations (Eocene), Southwestern Oregon

Studies of the depositional relations of the Umpqua and Tyee Formations (Eocene) in southwestern Oregon indicate a need for reassessing the correlations and currently used terminology. The Umpqua Formation (as herein restricted) consists of as much as 10,000 ft (3,000 m) of mudstone, sandstone, and conglomerate of nonmarine to deep marine origin. A basaltic basement that underlies the sedimentary rocks in most of the area and was formerly included in the Umpqua is herein considered a separate unit and assigned to the Siletz River Volcanics. A proposal to subdivide the Umpqua into three unconformity-bounded formations (in ascending order: Roseburg, Lookingglass, and Flournoy Formations) in the area west of Roseburg, Oregon, is not recognized in this report because of quest onable correlations and limited extent of some units. Foremost of these questionable correlations is that of the Flournoy Formation with rocks formerly assigned to the Tyee Formation in areas as far north as the latitude of Salem, Oregon. My investigations of depositional facies and lithologic criteria do not substantiate this correlation. The Tyee Formation, which conformably overlies the Umpqua, is a predominantly sandstone unit about 6,000 ft (1,800 m) thick, deposited in environments ranging from shallow marine and nonmarine deltaic on the south, to slope and deep marine basinal to the north. Deposition across the Umpqua-Tyee boundary contact represents a change in tectonic setting from active plate margin of the Umpqua to more stable marginal basin deposition of the Tyee. This change is also reflected in a change in provenance as indicated by the characteristic arkosic and micaceous aspects of Tyee sandstones.

Oregon↗

USGS2007

Pesticides and pesticide degradation products in stormwater runoff: Sacramento River Basin, California

Pesticides in stormwater runoff, within the Sacramento River Basin, California, were assessed during a storm that occurred in January 1994. Two organophosphate insecticides (diazinon and methidathion), two carbamate pesticides (molinate and carbofuran), and one triazine herbicide (simazine) were detected. Organophosphate pesticide concentrations increased with the rising stage of the hydrographs; peak concentrations were measured near peak discharge. Diazinon oxon, a toxic degradation product of diazinon, made up approximately 1 to 3 percent of the diazinon load. The Feather River was the principal source of organophosphate pesticides to the Sacramento River during this storm. The concentrations of molinate and carbofuran, pesticides applied to rice fields during May and June, were relatively constant during and after the storm. Their presence in surface water was attributed to the flooding and subsequent drainage, as a management practice to degrade rice stubble prior to the next planting. A photodegradation product of molinate, 4-keto molinate, was in all samples where molinate was detected and made up approximately 50 percent of the total molinate load. Simazine, a herbicide used in orchards and to control weeds along the roadways, was detected in the storm runoff, but it was not possible to differentiate the two sources of that pesticide to the Sacramento River.

Water Resources Bulletin↗

USGS1952

Glaciation and drainage changes in the fish Lake Plateau, Utah

The Fish Lake Plateau , nearly centrally located among the High Plateaus of Utah , exhibits glacial and other geomorphic features of regional significance. The plateau is divided into two areas by Fish Lake and the wide valley of Sevenmile Creek. The Fish Lake trough is a structural basin; Sevenmile Valley may be largely erosional. Volcanic rocks of Tertiary age underlie most of the plateau ; early Tertiary sedimentary rocks are also present. Glaciated canyons with well-developed cirques are especially prominent along the east-facing sides of the Fish Lake trough and Sevenmile Valley. Ice-eroded features occur over much of the plateau top. Near the mouths of several of the glaciated canyons are two conspicuous sets of moraines. The older set is more extensive and less rugged than the younger and occurs at somewhat lower elevations. Two substages of glaciation thus recognized are correlated with Wisconsin I and II of Ray; probable correlatives of Wisconsin III, IV, and V are represented by moraines which are younger than these two sets. Fish Lake drains north into Fremont River, a tributary of the Colorado River. An abandoned southern outlet and waterfall, the latter at a higher elevation than the present elevation of the original northern bedrock divide, indicate drainage reversal. Evidence is presented which suggests that this reversal was pre-glacial and probably the result of fault-block tilting.

Utah↗

USGS1993

Upper-crustal structure beneath the Columbia River Basalt Group, Washington: Gravity interpretation controlled by borehole and seismic studies

A three-dimensional gravity model based on deep-borehole stratigraphy, densities from borehole gravimetry, and crustal structure from deep seismic and electrical surveys puts limits on sub-basalt crustal structure in the northwest quadrant of the Columbia Plateau, Washington. The gravity model indicates that the Miocene Columbia River Basalt Group (CRBG) overlies a broad basin filled with sedimentary rocks that reach thicknesses in excess of 5 km; thickest sub-basalt sedimentary rocks are beneath the late Cenozoic Yakima basin. Analysis of residual gravity shows that the Eocene Chiwaukum graben does not continue beneath the CRBG and that sub-basalt sedimentary rocks are not thrust into the cores of the basalt anticlines in the Yakima fold belt. A gravity high that trends north-south in the center of the CRBG is probably caused by a broad basement ridge marked by thinner sedimentary rocks beneath the Columbia River basalts; the western edge of the north-south basement high is traced at the surface by the Hog Ranch-Naneum Ridge. A major crustal feature, the Olympic- Wallowa lineament, is expressed in the gravity field; the lineament crosses the north-south basement high but does not offset it, suggesting that any strike- slip motion on the lineament preceded development of the north-south basement high. An alternative interpretation of the north-south gravity high, based on a previous seismic study, relates it to a high-density structure in the crystalline basement, perhaps associated with a failed continental rift.

Idaho, Oregon, Washington↗

USGS1981

Water resources inventory of Connecticut Part 7: upper Connecticut River basin

The 508 square miles of the upper Connecticut River basin in north-central Connecticut include the basins of four major tributaries: the Scantic, Park, and Hockanum Rivers, and the Farmington River downstream from Tariffville. Precipitation over this area averaged 44 inches per year during 1931-60. In this period, an additional 3,800 billion gallons of water per year entered the basin in the main stem of the Connecticut River at the Massachusetts state line, about 230 billion gallons per year in the Farmington River at Tariffville, and about 10 billion gallons per year in the Seantic River at the Massachusetts state line. Some water was also imported from outside the basin by water-supply systems. About half the precipitation, 22.2 inches, was lost from the basin by evapotranspiration; the remainder flowed out of the study area in the Connecticut River at Portland. Variations in streamflow at 41 long-term continuous-record gaging stations are summarized in standardized graphs and tables that can be used to estimate streamflow characteristics at other sites. For example, mean-flow and two low-flow characteristics: (1) the 7-day annual minimum flow for 2-year and (2) 10-year recurrence intervals, have been determined for many partial-record stations throughout the basin. Of the 30 principal lakes, ponds, and reservoirs, two have usable storage capacities of more than 1 billion gallons. The maximum safe draft rate (regulated flow) of the largest of these, Shenipsit Lake at Rockville, is 6.5 million gallons per day for the 2-year and 30-year recurrence intervals (median and lowest annual flow). Floods have occurred within each month of the year but in different years. The greatest known flood on the Connecticut River was in March 1936; it had a peak flow of 130,000 cubic feet per second at Hartford. Since then, major floods have been reduced by flood-control measures. The major aquifers underlying the basin are composed of unconsolidated materials (stratified drift and till) and bedrock. Stratified drift overlies till and bedrock in valleys and lowlands in the eastern and western parts and in most of the broad central valley. The stratified drift generally ranges in thickness from 10 feet in small valleys to more than 200 feet in the Connecticut River Valley. Bedrock underlies the entire basin and is composed of (1) interbedded sedimentary and igneous rocks and (2) crystalline rocks. Ground-water sources yield from several million gallons per day from large well fields to 1 gallon per minute from single wells. Yields of 100 gal/min or more are most commonly obtained from screened wells tapping stratified-drift aquifers; amounts can be calculated by use of a series of graphs in conjunction with estimates of aquifer transmissivity and thickness. Eighteen areas underlain by good aquifers are selected as the most favorable locations for large-scale development of ground water. Selection of these areas is based on estimates of aquifer characteristics and the amount of water potentially available from induced infiltration of streamflow at low-flow conditions. Small to moderate water supplies can generally be obtained from any of the aquifers. Wells in bedrock yield at least a few gallons per minute at most sites. The probability of obtaining an adequate yield for domestic supply is greater in sedimentary than in crystalline bedrock and is also greater in stratified-drift overburden than in till. Where unaffected by man's activities, the water is of the calcium magnesium bicarbonate type, is generally low to moderate in dissolved-solids concentration, and ranges from soft to hard. In general, streamflow is less mineralized than ground water, particularly when it consists largely of direct runoff. However, streams become more highly mineralized during low-flow conditions, when most flow consists of more highly mineralized water discharged from aquifers. The median dissolved-solids concentration in water from 25 stream sites was 113 mg/L (milligrams per liter) during high flow, and 148 mg/L during low flow within the study period. Iron and manganese occur naturally in objectionable concentrations in some streams draining swamps and in some waters draining from sedimentary bedrock which contains iron- and manganese-bearing minerals. Man's activities have affected the water quality of streams in much of the area, particularly in the Hockanum and Park River basins. The degradation in quality in these streams is shown by wide and erratic changes in dissolved-solids concentration, excessive amounts of trace elements, a low dissolved-oxygen content, and abnormally high temperatures. Ground water within this area is degraded principally by induced infiltration of surface water that contains chemical wastes, by leachate from wastes stored or disposed of on the ground, and by effluents discharged from septic tanks. The quantity and quality of water are satisfactory for a wide variety of uses, and, with suitable treatment, the water may be used for most purposes. The total amount of water used in 1968 was more than 100 billion gallons. About 80 percent of this was used for industrial purposes, and 90 percent of the industrial water was obtained from surface-water sources. About 85 percent of the population was supplied with water for domestic use by 15 major public and municipal systems and 25 private associations. Analyses of water from the 13 largest systems show generally good quality.

Connecticut↗

USGS2007

Geochemical characterization of streambed sediment in the upper Illinois River basin

Geochemistry of fine-fraction streambed sediments collected from the upper Illinois River basin was surveyed in the fall of 1987 as part of the U.S. Geological Survey National Water-Quality Assessment pilot projects. The survey included 567 samples analyzed for 46 elements. Three distinctive distribution patterns were found for seven U.S. Environmental Protection Agency priority pollutants surveyed, as well as for boron and phosphorus: (1) enrichment of elements in the Chicago urban area and in streams draining the urban area relative to rural areas, (2) enrichment in main stems relative to tributaries, and (3) enrichment in low-order streams at high-population-density sites relative to low-population-density sites. Significant differences in background concentrations, as measured by samples from low-order streams, were observed among five subbasins in the study area. Uncertain geochemical correspondence between low-order, background sites and high-order, generally metal enriched sites prevented determination of background levels that would be appropriate for high-order sites. The within-sample ratio of enriched elements was variable within the Chicago area but was constant in the Illinois River downstream from Chicago. Element ratios imply a composite fine-fraction sediment in the Illinois River of 35-40 percent Des Plaines River origin and 60-65 percent Kankakee River origin.

Water Resources Bulletin↗

USGS1993

Late Cenozoic structure and correlations to seismicity along the Olympic-Wallowa Lineament, northwest United States

Late Cenozoic fault geometry, structure, paleoseismicity, and patterns of recent seismicity at two seismic zones along the Olympic-Wallowa lineament (OWL) of western Idaho, northeast Oregon, and southeast Washington indicate limited right-oblique slip displacement along multiple northwest-striking faults that constitute the lineament. The southern end of the OWL originates in the Long Valley fault system and western Snake River Plain in western Idaho, where it accommodates basin-and-range extension. Several kilometers west of the Long Valley fault system, post-middle Miocene displacement along the OWL has resulted in adjacent areas of uplift and subsidence. The OWL in northeast Oregon consists of a wide zone of northwest-striking faults and is associated with several large, inferred, pull-apart basins. The OWL then emerges from the Blue Mountain uplift as a much narrower zone of faults in the Columbia Plateau known as the Wallula fault zone (WFZ). Structural relationships in the WFZ strongly suggest that it is a right-slip extensional duplex. An ash horizon that correlates with the Mount St. Helens "J" composition (10.7 Ka) is displaced vertically 5 m by a normal fault along a segment of the WFZ. The intensity center for a damaging M = 6.1 earthquake in 1936 is located in the WFZ only a few kilometers northeast of this Holocene fault. Other youthful-appearing, strike-slip and thrust faults are located farther northwest along the OWL and may pose a seismic hazard to adjacent population centers and critical facilities.

Geological Society of America Bulletin↗

USGS2014

Geologic and physiographic controls on bed-material yield, transport, and channel morphology for alluvial and bedrock rivers, western Oregon

The rivers of western Oregon have diverse forms and characteristics, with channel substrates ranging from continuous alluvial gravel to bare bedrock. Analysis of several measurable morphologic attributes of 24 valley reaches on 17 rivers provides a basis for comparing nonalluvial and alluvial channels. Key differences are that alluvial reaches have greater bar area, greater migration rates, and show systematic correlation among variables relating grain size to bed-material transport capacity. We relate these differences between channel types to bed-material transport rates as derived from a coupled regional analysis of empirical sediment yield measurements and physical experiments of clast attrition during transport. This sediment supply analysis shows that overall bed-material transport rates for western Oregon are chiefly controlled by (1) lithology and basin slope, which are the key factors for bed-material supply into the stream network, and (2) lithologic control of bed-material attrition from in-transport abrasion and disintegration. This bed-material comminution strongly affects bed-material transport in the study area, reducing transport rates by 50%–90% along the length of the larger rivers in the study area. A comparison of the bed-material transport estimates with the morphologic analyses shows that alluvial gravel-bed channels have systematic and bounding relations between bed-material transport rate and attributes such as bar area and local transport capacity. By contrast, few such relations are evident for nonalluvial rivers with bedrock or mixed-bed substrates, which are apparently more influenced by local controls on channel geometry and sediment supply. At the scale of western Oregon, the physiographic and lithologic controls on the balance between bed-material supply and transport capacity exert far-reaching influence on the distribution of alluvial and nonalluvial channels and their consequently distinctive morphologies and behaviors—differences germane for understanding river response to tectonics and environmental perturbations, as well as for implementing effective restoration and monitoring strategies.

California, Nevada, Oregon, Washington↗

USGS2007

Distribution of nitrate and orthophosphate in selected streams in Central Nebraska

The Central Nebraska Basins is one of 60 study units in the National Water-Quality Assessment Program of the U.S. Geological Survey. The study unit includes the Platte River and two major tributaries, the Loup and Elkhorn Rivers. Agriculture is the predominant land use in the study unit, with only eight urbanized communities exceeding a population of 10,000. Water samples were collected from selected streams in the study unit during 1993- 1995. The data were used to assess the distribution of nitrogen compounds and phosphorus in the streams and to relate the concentrations of these constituents to environmental settings. This article focuses on dissolved nitrate and orthophosphate. Dissolved nitrate concentrations were highest (90th percentiles were less than 7.0 milligrams per liter as nitrogen) in areas with extensive cropland and pasture, where chemical fertilizers are intensively applied. Synoptic measurements conducted in March and August 1994 indicate that relatively little residual fertilizer, as nitrate, applied during a single crop-growing season enters streams. Dissolved nitrate concentrations showed a seasonal pattern, being highest during winter months and lowest during the late spring and summer. Dissolved orthophosphate concentrations tended to be low across the study unit, 90 percent of all analyses did not exceed 1.7 milligrams per liter as phosphorus.

Water Resources Bulletin↗

USGS1957

Drainage areas of Iowa streams

The drainage area of a stream at a specified location ordinarily may be defined as that area, measured in a horizontal plane, which is enclosed by a topographic divide such that direct surface runoff from precipitation would drain by gravity into the river basin above the specified point. One of the most important factors in the hydrologic computation for the design of structures on or over watercourses is the drainage area upstream from the point under consideration. Other hydrologic studies such as low-flow, flood-frequency analyses, rainfall-runoff correlations, stream density, and area-distance make use of this factor as a basic premise for computation. In order that the drainage-area information of the interior streams of Iowa be of uniform accuracy and available to all users of these data, this report has been compiled, and the drainage areas of all streams in excess of 5 square mies are listed. For the larger streams, drainage areas have been determined at numerous intermediate points. As a result of this report much basic background material has been compiled that will he useful in future hydrologic studies of drainage basin characteristics. This publication is limited to the presentation of the drainage-area data for the interior streams of the State. The methods of application of these data to the study of streamflow characteristics, and the design of related structures are properly the function of the design engineer and are not discussed herein.

Iowa↗

USGS1991

Relation of sediment load and flood-plain formation to climatic variability, Paria River drainage basin, Utah and Arizona

Suspended-sediment load, flow volume, and flood characteristics of the Paria River were analyzed to determine their relation to climate and flood-plain alluviation between 1923 and 1986. Flood-plain alluviation began about 1940 at a time of decreasing magnitude and frequency of floods in winter, summer, and fall. No floods with stages high enough to inundate the flood plain have occurred since 1980, and thus no flood-plain alluviation has occurred since then. The decrease in magnitude and frequency of floods appears to have resulted from a decrease in frequency of large storms, particularly dissipating tropical cyclones, and not from a decrease in annual or seasonal precipitation. Suspended-sediment load is highest in summer and fall, whereas flow volume is highest in winter. Fall shows the greatest interannual variability in suspended-sediment load, flow volume, and flood size because climatic conditions are most variable in fall. The relation between sediment load and discharge apparently did not change within the period of sediment sampling (1949-1976), even though the channel elevation and width changed significantly. Annual suspended-sediment loads estimated for periods before and after 1949-1976 show that decrease in suspended-sediment load caused by floodplain alluviation in the Paria River and other tributaries could have been a significant part of the decrease of suspended-sediment load in the Colorado River in the early 1940s.

Arizona, Utah↗

USGS2008

Geologic controls on the growth of petroleum reserves

The geologic characteristics of selected siliciclastic (largely sandstone) and carbonate (limestone and dolomite) reservoirs in North America (largely the continental United States) were investigated to improve our understanding of the role of geology in the growth of petroleum reserves. Reservoirs studied were deposited in (1) eolian environments (Jurassic Norphlet Formation of the Gulf Coast and Pennsylvanian-Permian Minnelusa Formation of the Powder River Basin), (2) interconnected fluvial, deltaic, and shallow marine environments (Oligocene Frio Formation of the Gulf Coast and the Pennsylvanian Morrow Formation of the Anadarko and Denver Basins), (3) deeper marine environments (Mississippian Barnett Shale of the Fort Worth Basin and Devonian-Mississippian Bakken Formation of the Williston Basin), (4) marine carbonate environments (Ordovician Ellenburger Group of the Permian Basin and Jurassic Smackover Formation of the Gulf of Mexico Basin), (5) a submarine fan environment (Permian Spraberry Formation of the Midland Basin), and (6) a fluvial environment (Paleocene-Eocene Wasatch Formation of the Uinta-Piceance Basin). The connection between an oil reservoir's production history and geology was also evaluated by studying production histories of wells in disparate reservoir categories and wells in a single formation containing two reservoir categories. This effort was undertaken to determine, in general, if different reservoir production heterogeneities could be quantified on the basis of gross geologic differences. It appears that reserve growth in existing fields is most predictable for those in which reservoir heterogeneity is low and thus production differs little between wells, probably owing to relatively homogeneous fluid flow. In fields in which reservoirs are highly heterogeneous, prediction of future growth from infill drilling is notably more difficult. In any case, success at linking heterogeneity to reserve growth depends on factors in addition to geology, such as engineering and technological advances and political or cultural or economic influences.

Bulletin↗

USGS1998

Bluebell field, Uinta basin: Reservoir characterization for improved well completion and oil recovery

Bluebell field is the largest oil-producing area in the Uinta basin of northern Utah. The field includes over 300 wells and has produced 137 MMbbl oil and 177 bcf gas from fractured Paleocene-Eocene lacustrine and fluvial deposits of the Green River and Wasatch (Colton) formations. Oil and gas are produced at depths of 10,500-13,000 ft (3330-3940 m), with the most prolific reservoirs existing in overpressured sandstones of the Colton Formation and the underlying Flagstaff Member of the lower Green River Formation. Despite a number of high-recovery wells (1-3 MMbbl), overall field recovery remains low, less than 10% original oil in place. This low recovery rate is interpreted to be at least partly a result of completion practices. Typically, 40-120 beds are perforated and stimulated with acid (no proppant) over intervals of up to 3000 ft (900 m). Little or no evaluation of individual beds is performed, preventing identification of good-quality reservoir zones, water-producing zones, and thief zones. As a result, detailed understanding of Bluebell reservoirs historically has been poor, inhibiting any improvements in recovery strategies. A recent project undertaken in Bluebell field as part of the U.S. Department of Energy's Class 1 (fluvial-deltaic reservoir) Oil Demonstration program has focused considerable effort on reservoir characterization. This effort has involved interdisciplinary analysis of core, log, fracture, geostatistical, production, and other data. Much valuable new information on reservoir character has resulted, with important implications for completion techniques and recovery expectations. Such data should have excellent applicability to other producing areas in the Uinta basin with reservoirs in similar lacustrine and related deposits.

Utah↗

USGS2013

Monitoring and understanding changes in heat waves, cold waves, floods, and droughts in the United States: State of knowledge

Weather and climate extremes have been varying and changing on many different time scales. In recent decades, heat waves have generally become more frequent across the United States, while cold waves have been decreasing. While this is in keeping with expectations in a warming climate, it turns out that decadal variations in the number of U.S. heat and cold waves do not correlate well with the observed U.S. warming during the last century. Annual peak flow data reveal that river flooding trends on the century scale do not show uniform changes across the country. While flood magnitudes in the Southwest have been decreasing, flood magnitudes in the Northeast and north-central United States have been increasing. Confounding the analysis of trends in river flooding is multiyear and even multidecadal variability likely caused by both large-scale atmospheric circulation changes and basin-scale “memory” in the form of soil moisture. Droughts also have long-term trends as well as multiyear and decadal variability. Instrumental data indicate that the Dust Bowl of the 1930s and the drought in the 1950s were the most significant twentieth-century droughts in the United States, while tree ring data indicate that the megadroughts over the twelfth century exceeded anything in the twentieth century in both spatial extent and duration. The state of knowledge of the factors that cause heat waves, cold waves, floods, and drought to change is fairly good with heat waves being the best understood.

Bulletin of the American Meteorological Society↗

USGS2010

Historical changes in annual peak flows in Maine and implications for flood-frequency analyses

Flood-frequency analyses use statistical methods to compute peak streamflows for selected recurrence intervals— the average number of years between peak flows that are equal to or greater than a specified peak flow. Analyses are based on annual peak flows at a stream. It has long been assumed that the annual peak streamflows used in these computations were stationary (non-changing) over very long periods of time, except in river basins subject to direct effects of human activities, such as urbanization and regulation. Because of the potential effects of global warming on peak flows, the assumption of peak-flow stationarity has recently been questioned. Maine has many streamgages with 50 to 105 years of recorded annual peak streamflows. In this study, this long-term record has been tested for historical flood-frequency stationarity, to provide some insight into future flood frequency. Changes over time in annual instantaneous peak streamflows at 28 U.S. Geological Survey streamgages with long-term data (50 or more years) and relatively complete records were investigated by examining linear trends for each streamgage’s period of record. None of the 28 streamgages had more than 5 years of missing data. Eight streamgages have substantial streamflow regulation. Because previous studies have suggested that changes over time may have occurred as a step change around 1970, step changes between each streamgage’s older record (start year to 1970) and newer record (1971 to 2006) also were computed. The median change over time for all 28 streamgages is an increase of 15.9 percent based on a linear change and an increase of 12.4 percent based on a step change. The median change for the 20 unregulated streamgages is slightly higher than for all 28 streamgages; it is 18.4 percent based on a linear change and 15.0 percent based on a step change. Peak flows with 100- and 5-year recurrence intervals were computed for the 28 streamgages using the full annual peak-flow record and multiple sub-periods of that record using the guidelines (Bulletin 17B) of the Interagency Advisory Committee on Water Data. Magnitudes of 100- and 5-year peak flows computed from sub-periods then were compared to those computed from the full period. Sub-periods of 30 years with starting years staggered by 10 years were evaluated (1907–36, 1917–46, 1927–56, 1937–66, 1947–76, 1957–86, 1967–96, and 1977–2006). Two other sub-periods were evaluated using older data (start-of-record to 1970) and newer data (1971 to 2006). The 5-year peak flow is used to represent small and relatively frequent flood flows in Maine, whereas the 100-year peak flow is used to represent large flood flows. The 1967–96 sub-period generated the highest 100- and 5-year peak flows overall when compared to peak flows based on the full period of record; the median difference for all 28 streamgages is 8 percent for 100- and 5-year peak flows. The 1977–2006 and 1971–2006 sub-periods also generated 100- and 5-year peak flows higher than peak flows based on the full period of record, but not as high as the peak flows based on the 1967–96 sub-period. The 1937–66 sub-period generated the lowest 100- and 5-year peak flows overall. The median difference from full-period peak flows is -11 percent for 100-year peak flows and -8 percent for 5-year peak flows. Overall, differences between peak flows based on the sub-periods and those based on the full periods, generated using the 20 unregulated streamgages, are similar to differences using all 28 streamgages. Increases in the 5- and 100-year peak flows based on recent years of record are, in general, modest when compared to peak flows based on complete periods of record. The highest peak flows are based on the 1967–96 sub-period rather than the most recent sub-period (1977-2006). Peak flows for selected recurrence intervals are sensitive to very high peak flows that may occur once in a century or even less frequently. It is difficult, therefore, to determine which approach will produce the most reliable future estimates of peak flows for selected recurrence intervals, using only recent years of record or the traditional method using the entire historical period. One possible conservative approach to computing peak flows of selected recurrence intervals would be to compute peak flows using recent annual peak flows and the entire period of record, then choose the higher computed value. Whether recent or entire periods of record are used to compute peak flows of selected recurrence intervals, the results of this study highlight the importance of using recent data in the computation of the peak flows. The use of older records alone could result in underestimation of peak flows, particularly peak flows with short recurrence intervals, such as the 5-year peak flows.

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