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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 82,000 reports authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Demography and population status of polar bears in western Hudson Bay Demography and population status of polar bears in western Hudson Bay
We evaluated the demography and population status of the Western Hudson Bay (WH) polar bear subpopulation for the period 1984-2011, using live-recapture data from research studies and management actions, and dead-recovery data from polar bears harvested for subsistence purposes or removed during human-bear conflicts. We used a Bayesian implementation of multistate capture-recapture...
Authors
Nicholas J. Lunn, Eric V Regher, Sabrina Servanty, Sarah J. Converse, Evan S. Richardson, Ian Stirling
Development of CE-QUAL-W2 models for the Middle Fork Willamette and South Santiam Rivers, Oregon Development of CE-QUAL-W2 models for the Middle Fork Willamette and South Santiam Rivers, Oregon
Hydrodynamic (CE-QUAL-W2) models of Hills Creek Lake (HCL), Lookout Point Lake (LOP), and Dexter Lake (DEX) on the Middle Fork Willamette River (MFWR), and models of Green Peter Lake and Foster Lake on the South Santiam River systems in western Oregon were updated and recalibrated for a wide range of flow and meteorological conditions. These CE-QUAL-W2 models originally were developed by...
Authors
Norman L. Buccola, Adam J. Stonewall, Annett B. Sullivan, Yoonhee Kim, Stewart A. Rounds
Distribution, habitat, and species description of the Diamond Darter, Crystallaria cincotta Distribution, habitat, and species description of the Diamond Darter, Crystallaria cincotta
Distribution, habitat, and species description of the Diamond Darter, Crystallaria cincotta.
Authors
Stuart A. Welsh
DOI remote sensing activities 2013 DOI remote sensing activities 2013
No abstract available.
Authors
Gregory I. Snyder
Effect of simulated tree canopy removal on a municipal wellfield in the Puget Sound aquifer system, Thurston County, Washington Effect of simulated tree canopy removal on a municipal wellfield in the Puget Sound aquifer system, Thurston County, Washington
Effects of tree canopy removal on a wellfield were simulated using a groundwater flow model characteristic of hydrogeologic settings in the Puget Sound aquifer system. Effects were estimated according to simulated changes in flow patterns that may result from tree canopy removal associated with varying degrees of residential development. The flow model used was a modified version of a...
Authors
Kenneth H. Johnson
Effects of acidic deposition and soil acidification on sugar maple trees in the Adirondack Mountains, New York Effects of acidic deposition and soil acidification on sugar maple trees in the Adirondack Mountains, New York
This study documents the effects of acidic deposition and soil acid-base chemistry on the growth, regeneration, and canopy condition of sugar maple (SM) trees in the Adirondack Mountains of New York. Sugar maple is the dominant canopy species throughout much of the northern hardwood forest in the State. A field study was conducted in 2009 in which 50 study plots within 20 small...
Authors
Timothy J. Sullivan, Gregory B. Lawrence, Scott W. Bailey, Todd C. McDonnell, G.T. McPherson
Estimating abundance of the Southern Hudson Bay polar bear subpopulation using aerial surveys, 2011 and 2012 Estimating abundance of the Southern Hudson Bay polar bear subpopulation using aerial surveys, 2011 and 2012
The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture-recapture studies indicate that abundance remained stable between 1986 and 2005, declines in body condition and survival were documented during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted...
Authors
Martyn E. Obbard, Kevin R. Middel, Seth P. Stapleton, Isabelle Thibault, Vincent Brodeur, Charles Jutras
Evaluation of National Atmospheric Deposition Program measurements for co-located Sites CO89 and CO98 at Rocky Mountain National Park, 2012 Evaluation of National Atmospheric Deposition Program measurements for co-located Sites CO89 and CO98 at Rocky Mountain National Park, 2012
Atmospheric wet-deposition monitoring in Rocky Mountain National Park included precipitation depth and aqueous chemical measurements at co-located National Atmospheric Deposition Program (NADP) sites CO89 and CO98 (Loch Vale) during 2012. The co-located sites are separated by approximately 6.5 meters horizontally and 0.5 meters in altitude, which meets NADP siting criteria. Median weekly...
Authors
Galveston Bay: Chapter D in Emergent wetlands status and trends in the northern Gulf of Mexico: 1950-2010 Galveston Bay: Chapter D in Emergent wetlands status and trends in the northern Gulf of Mexico: 1950-2010
The Galveston Bay estuary is located on the upper Texas Gulf coast (Lester and Gonzalez, 2002). It is composed of four major sub-bays - Galveston, Trinity, East, and West Bays. It is Texas’ largest estuary on the Gulf Coast with a total area of 155,399 hectares (384,000 acres) and 1,885 km (1,171 miles) of shoreline (Burgan and Engle, 2006). The volume of the bay has increased over the...
Authors
Lawrence R. Handley, Kathryn A. Spear, Eleonor Taylor, Cindy A. Thatcher
Geohydrologic and water-quality characterization of a fractured-bedrock test hole in an area of Marcellus shale gas development, Bradford County, Pennsylvania Geohydrologic and water-quality characterization of a fractured-bedrock test hole in an area of Marcellus shale gas development, Bradford County, Pennsylvania
Open-File Miscellaneous Investigation 13–01.1 presents the results of geohydrologic investigations on a 1,664-foot-deep core hole drilled in the Bradford County part of the Gleason 7.5-minute quadrangle in north-central Pennsylvania. In the text, the authors discuss their methods of investigation, summarize physical and analytical results, and place those results in context. Four...
Authors
Dennis W. Risser, John H. Williams, Kristen L. Hand, Rose-Anna Behr, Antonette K. Markowski
Geologic assessment of undiscovered oil and gas resources: Oligocene Frio and Anahuac Formations, United States Gulf of Mexico coastal plain and State waters Geologic assessment of undiscovered oil and gas resources: Oligocene Frio and Anahuac Formations, United States Gulf of Mexico coastal plain and State waters
The Oligocene Frio and Anahuac Formations were assessed as part of the 2007 U.S. Geological Survey (USGS) assessment of Tertiary strata of the U.S. Gulf of Mexico Basin onshore and State waters. The Frio Formation, which consists of sand-rich fluvio-deltaic systems, has been one of the largest hydrocarbon producers from the Paleogene in the Gulf of Mexico. The Anahuac Formation, an...
Authors
Sharon M. Swanson, Alexander W. Karlsen, Brett J. Valentine
Geologic map of Oldonyo Lengai (Oldoinyo Lengai) Volcano and surroundings, Arusha Region, United Republic of Tanzania Geologic map of Oldonyo Lengai (Oldoinyo Lengai) Volcano and surroundings, Arusha Region, United Republic of Tanzania
The geology of Oldonyo Lengai volcano and the southernmost Lake Natron basin, Tanzania, is presented on this geologic map at scale 1:50,000. The map sheet can be downloaded in pdf format for online viewing or ready to print (48 inches by 36 inches). A 65-page explanatory pamphlet describes the geologic history of the area. Its goal is to place the new findings into the framework of...
Authors
David R. Sherrod, Masota M. Magigita, Shimba Kwelwa