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Traveltime measurements were made during 2006 and 2007 along the Truckee River between Tahoe City, Calif., and Vista, Nev. Fluorescent rhodamine WT dye was injected at various locations along the river during streamflows ranging from 143 to 2,660 cubic feet per second. The resulting data, presented in tabular and graphic...

This report documents the SIM_ADJUST computer code. SIM_ADJUST surmounts an obstacle that is sometimes encountered when using universal model analysis computer codes such as UCODE_2005 (Poeter and others, 2005), PEST (Doherty, 2004), and OSTRICH (Matott, 2005; Fredrick and others (2007). These codes often read simulated equivalents from a list in...

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer....

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer....

Time-series photographs of the sea floor were obtained from an instrumented tripod deployed in western Massachusetts Bay at LT-A (42° 22.6' N, 70° 47.0' W; 32 m water depth; fig. 1) from December 1989 through September 2005. The photographs provide time-series observations of physical changes of the...

Water quality in the interior marsh of the Arthur R. Marshall Loxahatchee National Wildlife Refuge is characterized by low concentrations of major ions, principally sodium and chloride, and is affected primarily by natural seasonal processes, such as evapotranspiration, rainfall, and biological activity. During the dry season, evapotranspiration exceeds precipitation, and...

A study conducted in 2006 by the U.S. Geological Survey collected 57 surface rock samples from nine types of intrusive rock in the Iron Hill carbonatite complex. This intrusive complex, located in Gunnison County of southwestern Colorado, is known for its classic carbonatite-alkaline igneous geology and petrology. The Iron Hill...

Initial restoration of former salt evaporation ponds under the South Bay Salt Pond Restoration Project in San Francisco Bay included the changing of water-flow patterns and the monitoring of water quality of discharge waters from the ponds. Low dissolved oxygen (DO) concentrations became evident in discharge waters when the ponds...

The U.S. Geological Survey conducts a wide range of research in and around the Biscayne National Park region of southern Florida. This research encompasses the biologic, ecologic, meteorologic, geologic, and hydrologic components of the system, including water-quality analyses, ground-water modeling, hydrogeologic-data collection, ecologic-habitat evaluations, wetlands characterizations, biogeochemistry of ecosystems, and...

In 1974, the Colorado River Basin Salinity Control Act was passed into law. This law was enacted to address concerns regarding the salinity content of the Colorado River. The law authorized various construction projects in selected areas or "units" of the Colorado River Basin intended to reduce the salinity load...

During June-October 2005, water quality data were collected from Upper Klamath and Agency Lakes in Oregon, and meteorological data were collected around and within Upper Klamath Lake. Data recorded at two continuous water quality monitors in Agency Lake showed similar temperature patterns throughout the field season, but data recorded at...

Chlorinated solvents, including 1,1,2,2-tetrachloroethane, tetrachloroethene, trichloroethene, carbon tetrachloride, and chloroform, are reaching land surface in localized areas of focused ground-water discharge (seeps) in a wetland and tidal creek in the West Branch Canal Creek area, Aberdeen Proving Ground, Maryland. In cooperation with the U.S. Army Garrison, Aberdeen Proving Ground, Maryland,...

This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 2007. Potentiometric contours are based on water-level measurements collected at 554 wells during the period September 15-27, near the end of the wet season. Some contours are...

The U.S. Geological Survey (USGS) was one of numerous governmental, private, and academic entities that provided input to the report The State of the Nation?s Ecosystems published periodically by the Heinz Center. This report describes the sources of data and methods used by the USGS to develop selected water?quality indicators...

Onondaga Lake in Onondaga County, New York, has been identified as one of the Nation’s most contaminated lakes as a result of industrial and sanitary-sewer discharges and stormwater nonpoint sources, and has received priority cleanup status under the national Water Resources Development Act of 1990. A basin-scale precipitation-runoff model of...

The hydrogeologic framework was delineated for the ground-water flow system of the three basalt formations and two interbeds in the Yakima River Basin, Washington. The basalt units are nearly equivalent to the Saddle Mountains, Wanapum, and Grande Ronde. The two major interbed units between the basalt formations generally are referred...

An experimental field study of flows over bedforms was conducted on the Missouri River near St. Charles, Missouri. Detailed velocity data were collected under two different flow conditions along bedforms in this sand-bed river. The large river-scale data reflect flow characteristics similar to those of laboratory-scale flows, with flow separation...

The great 1906 San Francisco earthquake is perhaps the landmark event in the history of earthquake science. It began with a foreshock at 5:12 a.m. local time in the morning of 18 April 1906. Some 30 sec later, the main event initiated on the San Andreas fault, just off the San Francisco...

No abstract available....

Ecological surprises, substantial and unanticipated changes in the abundance of one or more species that result from previously unsuspected processes, are a common outcome of both experiments and observations in community and population ecology. Here, we give examples of such surprises along with the results of a survey of well-established...

Elevated selenium concentrations in streams are a water-quality concern in western Colorado. The U.S. Geologic Survey, in cooperation with the Colorado Department of Public Health and Environment, summarized selenium loading in the Lower Gunnison River Basin to support the development of total maximum daily selenium loads at sites that represent...

Landsat data have enabled continuous global monitoring of both human-caused and other land cover disturbances since 1972. Recently degraded performance and intermittent service of the Landsat 7 and Landsat 5 sensors, respectively, have raised concerns about the condition of global Earth observation programs. However, Landsat imagery is still useful for...

Plant species assemblages, communities or regional floras might be termed ‘saturated’ when additional immigrant species are unsuccessful at establishing due to competitive exclusion or other inter-specific interactions, or when the immigration of species is off-set by extirpation of species. This is clearly not the case for state, regional or national...

No abstract available....

We examined variables influencing nest predation on the endangered Least Bell's Vireo (Vireo bellii pusillus) at three spatial scales to determine what nest-site, habitat, or landscape characteristics affect the likelihood of nest predation and to determine the spatial distribution of predation risk and the variables influencing it. We used MARK...