Reports

We reexamine the geometry of the causative fault structure of the 1989 moment-magnitude-6.9 Loma Prieta earthquake in central California, using seismic-reflection, earthquake-hypocenter, and magnetic data. Our study is prompted by recent interpretations of a two-part dip of the San Andreas Fault (SAF) accompanied by a flower-like structure in the Coachella Valley, in southern California...

In response to the need for more information about selenium (Se) sources and transport, the U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board, completed a study that characterized Se loads in a reach of the Gunnison River between Delta and Grand Junction, Colo. This report identifies where possible dissolved Se loading is occurring in a study reach in the...

A multibeam echosounder is a type of sound navigation and ranging device that uses sound waves to “see” through even murky waters. Unlike a single beam echosounder (also known as a depth sounder or fathometer) that releases a single sound pulse in a single, narrow beam and “listens” for the return echo, a multibeam system emits a multidirectional radial beam to obtain information within...

Background In the fall of 2011, the U.S. Geological Survey (USGS) was afforded an opportunity to participate in an environmental monitoring study of the potential impacts of a deep, unconventional Marcellus Shale hydraulic fracturing site. The drill site of the prospective case study is the “Range Resources MCC Partners L.P. Units 1-5H” location (also referred to as the “RR–MCC” drill...

A review is given of the present feasibility for accurately mapping geoelectric fields across North America in near-realtime by modeling geomagnetic monitoring and magnetotelluric survey data. Should this capability be successfully developed, it could inform utility companies of magnetic-storm interference on electric-power-grid systems. That real-time mapping of geoelectric fields is a...

Management actions intended to increase growth and survival of pallid sturgeon (Scaphirhynchus albus) age-0 larvae on the Lower Missouri River require a comprehensive understanding of the geomorphic habitat template of the river. The study described here had two objectives relating to where channel-reconfiguration projects should be located to optimize effectiveness. The first objective...

As questions regarding the influence of increasing urbanization on water quality in the Edwards aquifer are raised, a better understanding of the sources, fate, and transport of compounds of concern in the aquifer—in particular, nutrients and pesticides—is needed to improve water management decision-making capabilities. The U.S. Geological Survey, in cooperation with the San Antonio...

The National Park Service (NPS) manages the Nation’s most iconic destinations that attract millions of visitors from across the Nation and around the world. Trip-related spending by NPS visitors generates and supports a considerable amount of economic activity within park gateway communities. This economic effects analysis measures how NPS visitor spending cycles through local economies

The White Dam in Clarke County, Georgia, has been proposed for breaching. Efforts to determine potential risks to downstream biota included assessments of sediment collected in the vicinity of the dam. Sediments collected from sites upstream and downstream from the dam were evaluated for toxicity in 42-day exposures using the freshwater amphipod Hyalella azteca. Endpoints of the study...

Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and longterm...

Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term...

Vegetation in the riparian zone (the area immediately adjacent to streams, such as stream banks) along the Colorado River downstream of Glen Canyon Dam, Arizona, supports many ecosystem and societal functions. In both Glen Canyon and Grand Canyon, this ecosystem has changed over time in response to flow alterations, invasive species, and recreational use. Riparian-vegetation cover and...