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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 721 records · Page 40Linked to original sources
USGS2000

Forest clearing and regional landsliding

The influence of forest clearing on landsliding is central to long-standing concern over the effects of timber harvesting on slope stability. Here we document a strong topographic control on shallow landsliding by combining unique ground-based landslide surveys in an intensively monitored study area with digital terrain modeling using high-resolution laser altimetry and a coarser resolution regional study of 3224 landslides. As predicted by our digital terrain–based model, landslides occur disproportionately in steep, convergent topography. In terrain predicted to be at low risk of slope failure, a random model performs equally well to our mechanism-based model. Our monitoring shows that storms with 24 hr rainfall recurrence intervals of less than 4 yr triggered landslides in the decade after forest clearing and that conventional monitoring programs can substantially underestimate the effects of forest clearing. Our regional analysis further substantiates that forest clearing dramatically accelerates shallow landsliding in steep terrain typical of the Pacific Northwest.

Oregon↗
USGS2001

Seismic images and fault relations of the Santa Monica thrust fault, West Los Angeles, California

In May 1997, the US Geological Survey (USGS) and the University of Southern California (USC) acquired high-resolution seismic reflection and refraction images on the grounds of the Wadsworth Veterans Administration Hospital (WVAH) in the city of Los Angeles (Fig. 1a,b). The objective of the seismic survey was to better understand the near-surface geometry and faulting characteristics of the Santa Monica fault zone. In this report, we present seismic images, an interpretation of those images, and a comparison of our results with results from studies by Dolan and Pratt (1997), Pratt et al. (1998) and Gibbs et al. (2000). The Santa Monica fault is one of the several northeast-southwest-trending, north-dipping, reverse faults that extend through the Los Angeles metropolitan area (Fig. 1a). Through much of area, the Santa Monica fault trends subparallel to the Hollywood fault, but the two faults apparently join into a single fault zone to the southwest and to the northeast (Dolan et al., 1995). The Santa Monica and Hollywood faults may be part of a larger fault system that extends from the Pacific Ocean to the Transverse Ranges. Crook et al. (1983) refer to this fault system as the Malibu Coast-Santa Monica-Raymond-Cucamonga fault system. They suggest that these faults have not formed a contiguous zone since the Pleistocene and conclude that each of the faults should be treated as a separate fault with respect to seismic hazards. However, Dolan et al. (1995) suggest that the Hollywood and Santa Monica faults are capable of generating Mw 6.8 and Mw 7.0 earthquakes, respectively. Thus, regardless of whether the overall fault system is connected and capable of rupturing in one event, individually, each of the faults present a sizable earthquake hazard to the Los Angeles metropolitan area. If, however, these faults are connected, and they were to rupture along a continuous fault rupture, the resulting hazard would be even greater. Although the Santa Monica fault represents a hazard to millions of people, its lateral extent and rupture history are not well known, due largely to limited knowledge of the fault location, geometry, and relationship to other faults. The Santa Monica fault has been obscured at the surface by alluvium and urbanization. For example, Dolan et al. (1995) could find only one 200-m-long stretch of the Santa Monica fault that was not covered by either streets or buildings. Of the 19-km length onshore section of the Santa Monica fault, its apparent location has been delineated largely on the basis of geomorphic features and oil-well drilling. Seismic imaging efforts, in combination with other investigative methods, may be the best approach in locating and understanding the Santa Monica fault in the Los Angeles region. This investigation and another recent seismic imaging investigation (Pratt et al., 1998) were undertaken to resolve the near-surface location, fault geometry, and faulting relations associated with the Santa Monica fault.

California↗
USGS2015

Sequence stratigraphic framework of upper pliocene to holocene sediments of the Los Angeles Basin, California: Implications for aquifer architecture

Executive Summary Groundwater provides more than one-third of the municipal water supply for the coastal Los Angeles Basin and defining the aquifer architecture is a high priority for ground-water managers. Sequence stratigraphy, the state-of-the-art method for delineating reservoir geometry and continuity in the petroleum industry, is now being incorporated into ground water resource assessments and environmental investigations. By evaluating subsurface data using sequence stratigraphy, the geometry and distribution of aquifer and aquitard sediments are linked to the original depositional processes that formed the sediments. Skyline Ridge, Inc., the U.S. Geological Survey (USGS), in cooperation with Los Angeles County Department of Public Works (LACDPW) and the Water Replenishment District of Southern California (WRDSC) completed an investigation of the Wilmington – Long Beach area by integrating data from new exploratory research boreholes, marine reflection seismic, vintage land reflection seismic, and high-resolution gravity measurements. Sequence stratigraphy is shown to define pathways for saltwater intrusion into freshwater coastal aquifers by integrating preexisting data with (1) the new borehole observations and (2) structural and physical properties data derived from the geophysical measurements. By constructing a series of seismic reflection and well log cross sections (presented as sheets), this investigation further defines and delineates ten sequences of Late Pliocene to Holocene age in the Wilmington – Long Beach area of the Los Angeles Basin. These sequences were first described by Ponti and others (2007), and the implications for sea water intrusion was discussed by Edwards and others (2009a). In addition, this investigation presents regional seismic facies – environment of deposition maps for the five youngest sequences: 1) the Dominquez Sequence; 2) the Mesa Sequence; 3) the Pacific Sequence; the Harbor Sequence; and 4) the Bent Spring Sequence. The stratigraphic framework established in the Wilmington – Long Beach area is extended into the Central Basin of the greater Los Angeles area by utilizing 1980s and older vintage petroleum exploration land seismic reflection data. Tying this data to the available groundwater monitoring well network in the Central and West Coast Basins demonstrate aquifer correlation problems, and may provide insights into establishing a more robust groundwater model for the greater Los Angeles Basin area.

Book↗
USGS1974

Chemical variations across the Alaska-Aleutian Range batholith

A study of 79 chemical analyses of plutonic rocks in the northern part of the Alaska-Aleutian Range batholith shows that K 2 O and SiO 2 in Late Cretaceous and Tertiary rocks decrease toward the Pacific margin and that Al 2 O 3 and CaO increase. Plots for Fe 2 O 3 , FeO, MgO, and TiO 2 suggest a possible increase toward the Pacific margin; Na 2 O, H 2 O+, and MnO show no significant trends across the batholith. Oxide trends for groups of plutons in the western and eastern parts of the batholith in general are opposite that of the groups combined. For the Jurassic plutonic rocks, K 2 O may decrease toward the Pacific margin; other oxides show considerable scatter, and meaningful trends are not readily apparent. The oxide trends across the batholith are similar to trends across the central Sierra Nevada batholith of California, with the exception of SiO 2 and A1 2 O 3 , which show no significant changes. In the Coast Range batholith of British Columbia, potassium also increases away from the Pacific margin. The increase in K 2 O toward the continent in the Alaska-Aleutian Range batholith is similar to that found across Quaternary volcanic island arcs, where K 2 O content increases directly with increasing depth to inclined seismic zones. This increase suggests that generation of magma may have taken place along, or above, a paleoseismic zone. Geologic evidence supports such a model for the Jurassic plutonic rocks, which represent the roots of an early Mesozoic magmatic arc that probably formed above a descending oceanic plate. However, the hypothesis that magma for Late Cretaceous and Tertiary plutonic rocks was generated along seismic zones does not fit available geologic evidence, and an anatectic model cannot be ruled out.

Alaska↗
USGS2011

Terrestrial forest management plan for Palmyra Atoll

This 'Terrestrial Forest Management Plan for Palmyra Atoll' was developed by the U.S. Geological Survey (USGS) for The Nature Conservancy (TNC) Palmyra Program to refine and expand goals and objectives developed through the Conservation Action Plan process. It is one in a series of adaptive management plans designed to achieve TNC's mission toward the protection and enhancement of native wildlife and habitat. The 'Terrestrial Forest Management Plan for Palmyra Atoll' focuses on ecosystem integrity and specifically identifies and addresses issues related to assessing the status and distribution of resources, as well as the pressures acting upon them, most specifically nonnative and potentially invasive species. The plan, which presents strategies for increasing ecosystem integrity, provides a framework to implement and track the progress of conservation and restoration goals related to terrestrial resources on Palmyra Atoll. The report in its present form is intended to be an overview of what is known about historical and current forest resources; it is not an exhaustive review of all available literature relevant to forest management but an attempt to assemble as much information specific to Palmyra Atoll as possible. Palmyra Atoll is one of the Northern Line Islands in the Pacific Ocean southwest of the Hawai`ian Islands. It consists of many heavily vegetated islets arranged in a horseshoe pattern around four lagoons and surrounded by a coral reef. The terrestrial ecosystem consists of three primary native vegetation types: Pisonia grandis forest, coastal strand forest, and grassland. Among these vegetation types, the health and extent of Pisonia grandis forest is of particular concern. Overall, the three vegetation types support 25 native plant species (two of which may be extirpated), 14 species of sea birds, six shore birds, at least one native reptile, at least seven native insects, and six native land crabs. Green and hawksbill turtles forage at Palmyra Atoll, and though rarely documented, beach nesting could be affected by terrestrial management actions. There are various nonnative or invasive species throughout the terrestrial ecosystem. The most notable examples of terrestrial invasive species include coconut palms (Cocos nucifera) and black rats (Rattus rattus). Although it is unclear whether they are nonnative, coconut palms are currently the most dominant plant across Palmyra Atoll. They compete with native plant species for space and resources and are potentially detrimental to sea birds dependent on native vegetation for roosting and nesting habitat. This competition in turn impacts nutrient resource availability, thereby reshaping energy flow in the ecosystem. Black rats are known to prey on ground-nesting sea birds and are likely responsible for the lack of burrowing sea bird reproduction at Palmyra Atoll. In addition, they may be facilitating the invasion of other nonnative species and negatively impacting other native fauna. Although the extent and impacts of these and other nonnative and (or) invasive species are not fully understood, the extent and impacts are clearly a threat to the native species and one of the most urgent threats to the overall ecosystem integrity of Palmyra Atoll. This 'Terrestrial Forest Management Plan for Palmyra Atoll' addresses issues related to invasive species and other problems. Priority goals are established as are associated objectives and strategies. The overarching goal is to perpetuate and where possible restore terrestrial ecosystem integrity through the following techniques: 1. Habitat management: Maintain and enhance habitat to the extent possible to sustain thriving Pisonia grandis forest, coastal strand forest, endemic grassland, self-sustaining populations of sea birds, shore birds, coconut crabs, native lizards, and native insects. 2. Monitoring and assessment: Acquire information on distribution and abundance as needed for conservation of each resour

Open-File Report↗
USGS2005

Calculation of area and volume for the south part of Great Salt Lake, Utah

The U.S. Geological Survey, in cooperation with the Utah Department of Natural Resources, Division of Wildlife Resources, collected bathymetric data for the south part of Great Salt Lake during 2002-04 using a single-beam, high-definition fathometer and real-time differential global positioning system. About 7.6 million depth measurements were collected along more than 930 miles (1,690 kilometers) of survey transects. Sound-velocity profiles were obtained in conjunction with the bathymetric data to provide time-of-travel corrections to the depth calculations. Data were processed with commercial hydrographic software and exported into geographic information system (GIS) software for mapping and calculation of area and volume. Area and volume calculations show a maximum area of about 508,000 acres (2,056 square kilometers) and a maximum volume of about 9,257,000 acre-feet (11.42 cubic kilometers) at a water-surface altitude of 4,200 feet (1,280 meters). Minimum water-surface altitude of the south part of Great Salt Lake is just below 4,167 feet (1,279 meters) in the area just south of the Union Pacific railroad causeway halfway between Promontory Point and the western edge of the lake. At this altitude, and continuing up to about 4,176 feet (1,279 meters), the south part of the lake is separated into two areas by a ridge extending from Promontory Point to Hat Island. Calculations for area and volume are based on a low altitude of 4,167 feet (1,279 meters) to a high altitude of 4,200 feet (1,280 meters).

Utah↗
USGS1967

Effects of the Truckee, California, earthquake of September 12, 1966

The Truckee, Calif., earthquake of September 12, 1966, had a magnitude of 5.4 on the Richter scale, as reported by the U.S. Coast and Geodetic Survey. It was felt over an area extending from San Francisco eastward to Salt Lake City and from Bakersfield northward beyond Chico, Calif. Ground breakage due to seismic shaking occurred in unconsolidated alluvium along a zone about 10 miles long that trends about N. 30° E. and extends from a point west of Prosser Reservoir, 4 miles northeast of Truckee, to Hoke Valley. The concentration of ground breakage along this zone suggests that it may be related to a subsurface northeastward-trending fault rather than to buried extensions of the northwestward-trending faults that dominate the regional geologic structure. Other effects of the earthquake include the following: (1) Damage to Prosser and Boca Dams, (2) minor damage to several bridges on Interstate Highway 80, (3) several earthquake-generated slumps or landslides on Interstate Highway 80 between Boca Dam and the California-Nevada boundary, (4) damage to the caretaker's house at Boca Dam and a lumber shed at Loyalton, (5) damage by falling rocks to the Farad powerhouse, to the wooden flume which supplies water to the powerhouse, and to the Southern Pacific Lines in Truckee Canyon, (6) minor damage to water wells and water distribution systems, particularly at Truckee, and (7) rejuvenation of springs throughout the Truckee-Russel Valley area.

Arizona, California, Idaho, Nevada, Oregon, Utah↗
USGS2012

U.S. Department of the Interior Southeast Climate Science Center Science and Operational Plan

Climate change challenges many of the basic assumptions routinely used by conservation planners and managers, including the identification and prioritization of areas for conservation based on current environmental conditions and the assumption those conditions could be controlled by management actions. Climate change will likely alter important ecosystem drivers (temperature, precipitation, and sea-level rise) and make it difficult, if not impossible, to maintain current environmental conditions into the future. Additionally, the potential for future conservation of non-conservation lands may be affected by climate change, which further complicates resource planning. Potential changes to ecosystem drivers, as a result of climate change, highlight the need to develop and adapt effective conservation strategies to cope with the effects of climate and landscape change. The U.S. Congress, recognized the potential effects of climate change and authorized the creation of the U.S. Geological Survey National Climate Change and Wildlife Science Center (NCCWSC) in 2008. The directive of the NCCWSC is to produce science that supports resource-management agencies as they anticipate and adapt to the effects of climate change on fish, wildlife, and their habitats. On September 14, 2009, U.S. Department of the Interior (DOI) Secretary Ken Salazar signed Secretarial Order 3289 (amended February 22, 2010), which expanded the mandate of the NCCWSC to address climate-change-related impacts on all DOI resources. Secretarial Order 3289 "Addressing the Impacts of Climate Change on America's Water, Land, and Other Natural and Cultural Resources," established the foundation of two partner-based conservation science entities: Climate Science Centers (CSC) and their primary partners, Landscape Conservation Cooperatives (LCC). CSCs and LCCs are the Department-wide approach for applying scientific tools to increase the understanding of climate change, and to coordinate an effective response to its impacts on tribes and the land, water, ocean, fish and wildlife, and cultural-heritage resources that DOI manages. The NCCWSC is establishing a network of eight DOI CSCs (Alaska, Southeast, Northwest, North Central, Pacific Islands, Southwest, Northeast, and South Central) that will work with a variety of partners and stakeholders to provide resource managers the tools and information they need to help them anticipate and adapt conservation planning and design for projected climate change. The Southeast CSC, a federally led research collaboration hosted by North Carolina State University, was established in 2010. The Southeast CSC brings together the expertise of federal and university scientists to address climate-change priority needs of federal, state, non-governmental, and tribal resource managers. This document is the first draft of a science and operational plan for the Southeast CSC. The document describes operational considerations, provides the context for climate-change impacts in the Southeastern United States, and establishes six major science themes the Southeast CSC will address in collaboration with partners. This document is intended to be reevaluated and modified as partner needs change.

Open-File Report↗
USGS1959

Eighth progress report on the cooperative investigation of springs and streamflow in the Tecolote Tunnel area of Santa Barbara County, California

This report is the eighth in a continuing series of progress reports giving the results of discharge measurements made at selected springs and streams in the Tecolote Tunnel area of the Santa Ynez Mountains. The measurement program was begun on its present scale in the latter part of 1948 by the U. S. Geological Survey at the request of the U. S. Bureau of Reclamation and has been continued under a cooperative agreement with the Santa Barbara County Water Agency since July 1, 1949, under which each agency pays half the cost of the investigation. The purpose of the program is to obtain factual data to assist in determining what effect, if any, the inflow of ground water into Tecolote Tunnel will have on surface-water resources in the vicinity of the tunnel. The area involved in the program, shown on plate 1, was made large enough to include a number of springs and streams believed to be outside the zone of influence of the tunnel. Tecolote Tunnel, completed in March 1956, was built by the Bureau of Reclamation for the purpose of conveying water from Cachuma Reservoir to the city of Santa Barbara and adjacent coastal communities. The alinement of the tunnel is essentially north and south through the center of a region that extends from the Painted Cave area on the east to Refugio Pass on the west and from the Santa Ynez River on the north to the Pacific Ocean on the south. Storage, in Cachuma Reservoir began November 16, 1952. Roads within the area covered by Cachuma Reservoir have been relocated since plate 1 was prepared. The purpose of this progress report is to make available the factual data obtained from July 1956 to June 1958.

California↗
USGS1999

Earthquake probabilities in the San Francisco Bay region: 2000 to 2030 - A summary of findings

The San Francisco Bay region sits astride a dangerous “earthquake machine,” the tectonic boundary between the Pacific and North American Plates. The region has experienced major and destructive earthquakes in 1838, 1868, 1906, and 1989, and future large earthquakes are a certainty. The ability to prepare for large earthquakes is critical to saving lives and reducing damage to property and infrastructure. An increased understanding of the timing, size, location, and effects of these likely earthquakes is a necessary component in any effective program of preparedness. This study reports on the probabilities of occurrence of major earthquakes in the San Francisco Bay region (SFBR) for the three decades 2000 to 2030. The SFBR extends from Healdsberg on the northwest to Salinas on the southeast and encloses the entire metropolitan area, including its most rapidly expanding urban and suburban areas. In this study a “major” earthquake is defined as one with M≥6.7 (where M is moment magnitude). As experience from the Northridge, California (M6.7, 1994) and Kobe, Japan (M6.9, 1995) earthquakes has shown us, earthquakes of this size can have a disastrous impact on the social and economic fabric of densely urbanized areas. To reevaluate the probability of large earthquakes striking the SFBR, the U.S. Geological Survey solicited data, interpretations, and analyses from dozens of scientists representing a wide crosssection of the Earth-science community (Appendix A). The primary approach of this new Working Group (WG99) was to develop a comprehensive, regional model for the long-term occurrence of earthquakes, founded on geologic and geophysical observations and constrained by plate tectonics. The model considers a broad range of observations and their possible interpretations. Using this model, we estimate the rates of occurrence of earthquakes and 30-year earthquake probabilities. Our study considers a range of magnitudes for earthquakes on the major faults in the region—an innovation over previous studies of the SFBR that considered only a small number of potential earthquakes of fixed magnitude.

California↗
USGS2006

Calculation of area and volume for the north part of Great Salt Lake, Utah

The U.S. Geological Survey, in cooperation with the Utah Department of Natural Resources, Division of Forestry, Fire, and State Lands, collected bathymetric data for the north part of Great Salt Lake during the spring and early summer of 2006 using a single-beam, high-definition fathometer and real-time differential global positioning system. About 5.2 million depth measurements were collected along more than 765 miles (1,230 kilometers) of survey transects. Sound-velocity profiles were obtained in conjunction with the bathymetric data to provide time-of-travel corrections to the depth calculations. Data were processed with commercial hydrographic software and exported into geographic information system (GIS) software for mapping and calculation of area and volume. Area and volume calculations show a maximum area of about 385,000 acres (1,560 square kilometers) and a maximum volume of about 5,693,000 acre-feet (about 7 cubic kilometers) at a water-surface altitude of 4,200 feet (1,280 meters). Minimum natural water-surface altitude of the north part of Great Salt Lake is just below 4,167 feet (1,270 meters) in the area just north of the Union Pacific railroad causeway halfway between Saline and the western edge of the lake. The north part of Great Salt Lake generally grades gradually to the west and north and is bounded by steep scarps along its eastern border. Calculations for area and volume are based on a low altitude of 4,167 feet (1,270 meters) to a high altitude of 4,200 feet (1,280 meters).

Utah↗
USGS2006

Cadmium risks to freshwater life: derivation and validation of low-effect criteria values using laboratory and field studies

In 2001, the U.S. Environmental Protection Agency (EPA) released updated aquatic life criteria for cadmium. Since then, additional data on the effects of cadmium to aquatic life have become available from studies supported by the EPA, Idaho Department of Environmental Quality (IDEQ), and the U.S. Geological Survey, among other sources. Updated data on the effects of cadmium to aquatic life were compiled and reviewed and low-effect concentrations were estimated. Low-effect values were calculated using EPA's guidelines for deriving numerical national water-quality criteria for the protection of aquatic organisms and their uses. Data on the short-term (acute) effects of cadmium on North American freshwater species that were suitable for criteria derivation were located for 69 species representing 57 genera and 33 families. For longer-term (chronic) effects of cadmium on North American freshwater species, suitable data were located for 28 species representing 21 genera and 17 families. Both the acute and chronic toxicity of cadmium were dependent on the hardness of the test water. Hardness-toxicity regressions were developed for both acute and chronic datasets so that effects data from different tests could be adjusted to a common water hardness. Hardness-adjusted effects values were pooled to obtain species and genus mean acute and chronic values, which then were ranked by their sensitivity to cadmium. The four most sensitive genera to acute exposures were, in order of increasing cadmium resistance, Oncorhynchus (Pacific trout and salmon), Salvelinus ('char' trout), Salmo (Atlantic trout and salmon), and Cottus (sculpin). The four most sensitive genera to chronic exposures were Hyalella (amphipod), Cottus, Gammarus (amphipod), and Salvelinus. Using the updated datasets, hardness dependent criteria equations were calculated for acute and chronic exposures to cadmium. At a hardness of 50 mg/L as calcium carbonate, the criterion maximum concentration (CMC, or 'acute' criterion) was calculated as 0.75 mug/L cadmium using the hardness-dependent equation CMC = e(0.8403 ? ln(hardness)-3.572) where the 'ln hardness' is the natural logarithm of the water hardness. Likewise, the criterion continuous concentration (CCC, or 'chronic' criterion) was calculated as 0.37 mug/L cadmium using the hardness-dependent equation CCC = (e(0.6247 ? ln(hardness)-3.384)) ? (1.101672 - ((ln hardness) ? 0.041838))). Using data that were independent of those used to derive the criteria, the criteria concentrations were evaluated to estimate whether adverse effects were expected to the biological integrity of natural waters or to selected species listed as threatened or endangered. One species was identified that would not be fully protected by the derived CCC, the amphipod Hyalella azteca. Exposure to CCC conditions likely would lead to population decreases in Hyalella azteca, the food web consequences of which probably would be slight if macroinvertebrate communities were otherwise diverse. Some data also suggested adverse behavioral changes are possible in fish following long-term exposures to low levels of cadmium, particularly in char (genus Salvelinus). Although ambiguous, these data indicate a need to periodically review the literature on behavioral changes in fish following metals exposure as more information becomes available. Most data reviewed indicated that criteria conditions were unlikely to contribute to overt adverse effects to either biological integrity or listed species. If elevated cadmium concentrations that approach the chronic criterion values occur in ambient waters, careful biological monitoring of invertebrate and fish assemblages would be prudent to validate the prediction that the assemblages would not be adversely affected by cadmium at criterion concentrations.

Scientific Investigations Report↗
USGS2015

U.S. Geological Survey Chesapeake science strategy, 2015-2025—Informing ecosystem management of America’s largest estuary

Executive Summary The U.S. Geological Survey (USGS) has the critical role of providing scientific information to improve the understanding and management of the Chesapeake Bay ecosystem. The USGS works with Federal, State, and academic science partners to provide research and monitoring, and communicate results of these activities to enhance ecosystem management for both the Chesapeake and other National ecosystems. The USGS Chesapeake Science Strategy was prepared to guide science activities to address the Chesapeake Bay Watershed Agreement (2014–2025), to support the Department of the Interior (DOI) involvement in the Bay restoration efforts, and align with the USGS Mission Area (MA) Science strategies. The Chesapeake Bay is our Nation’s largest estuary, and provides critical goods and services to the people, fish, and wildlife that use the 64,000-square-mile watershed. The Chesapeake Bay watershed contains over 3,600 species of fish, wildlife, and plants and provides spawning grounds for many ecologically and economically important species including striped bass and blue crabs. The Bay watershed lies in the heart of the Atlantic Flyway and has 29 species of waterfowl, about 1 million of which winter in the region. The size of the Chesapeake seafood harvest is third in the Nation, only behind the Atlantic and Pacific Oceans. Along with agricultural production, tourism, and recreation, the estimated economic value of the services from the Chesapeake Bay watershed is about $100 billion annually. However, the health of the Bay ecosystem began to decline at the beginning of the 20th century due to overfishing and increasing human population and associated land change. The Chesapeake Bay Program (CBP) is the Federal-State cooperative effort that started in 1983 to restore the Bay and watershed. Given the ecological and economic importance of the Chesapeake ecosystem, President Obama issued an Executive Order (EO) in 2009 for increased Federal leadership in the CBP to enhance the pace of restoration, and the supporting strategy was released in 2010. The EO directed the Federal Government, including the U.S. Department of the Interior (DOI), represented by the National Park Service (NPS), the U.S. Fish & Wildlife Service (FWS), and the USGS, to expand its efforts and increase leadership to restore the Bay and its watershed. The USGS and other Federal agencies expanded their activities in 2011 to meet the President’s Chesapeake EO. Since the EO was released, there have been several important changes in the USGS, DOI, and the CBP including: (1) the Chesapeake Bay Watershed Agreement, (2) increased DOI leadership in the CBP, and (3) the release of the USGS MA science strategies. The EO strategy served as a foundation for the Chesapeake Bay Watershed Agreement that was signed in 2014 by the CBP Partners, and has goals and outcomes to be met by 2025. The USGS developed the Chesapeake Science Strategy to guide our activities to address the Chesapeake Bay Watershed Agreement, DOI leadership in the CBP, and USGS MA strategies. Improving the understanding of fish and wildlife population and health, and the factors affecting their condition is the emphasis of the Strategy. The science focuses on documenting the critical ecosystem connections in the Chesapeake, and providing implications to enhance decision making for restoration and conservation activities. The revised Strategy has four themes that address 7 of the 10 goals in the Chesapeake Bay Watershed Agreement: Enhance science to support restoration, and conservation of fish, wildlife, and critical habitats. Characterize and explain changes in water quality, and its effect on freshwater and estuarine ecosystems. Assess and forecast effects of climate and land change on ecosystem conditions. Synthesize and provide information to support ecosystem management. The structure and function of biological communities of the Bay and its watershed are extremely complex and are affected by a variety of stressors and conditions. To better define the issues being addressed, the USGS has developed cross-cutting questions that define some of the most important scientific challenges where multiple disciplines and collaborators are needed to address an issue. The initial questions include: How do land and climate changes affect freshwater fish communities, health, and habitats? What are the relations among land use, water quality, contaminants, and the health of fish and wildlife? How are coastal wetlands and their carrying capacity for waterbirds affected by changing climate and land use? How is the water quality of rivers and estuaries responding to restoration actions, and changing land use? What are some of the best opportunities for management actions to benefit multiple restoration outcomes?

Delaware, Maryland, New York, Pennsylvania, Virgin↗
USGS1962

Data on uranium and radium in ground water in the United States, 1954 to 1957

This report is one of a series resulting from a study by the U.S. Geological Survey to determine the occurrence and distribution of naturally radioactive substances in water. From 1954-57 uranium and radium concentrations were determined in 561 samples, mainly of ground water, having wide geologic and geographic distribution. These concentrations, together with data on the hydrologic and geologic environment, the beta-gamma activity, and the chemical characteristics of each sample, are tabulated by States. The conterminous United States was subdivided into 10 geotectonic regions to facilitate statistical interpretation of the occurrence of uranium and radium in fresh water in approximately homogeneous geologic provinces. For each geotectonic region, the range and median were determined for the concentrations of radium and uranium; for regions from which sufficient data were available, log-normal frequency distribution curves were calculated and superimposed on histograms of radium and uranium concentrations in the samples. An "anomaly threshold" is suggested for both radioelements for each region analyzed statistically. The western stable region had the greatest median and highest "anomaly threshold" for uranium. This region also had the highest "anomaly threshold" for radium, but the largest median for radium was found for samples collected in the Ozark-Ouachita system. The median concentration for uranium was lowest for the Atlantic and Gulf Coastal Plain and the Pacific orogenic belt. This latter region also had the lowest median-radium content.

Professional Paper↗
USGS2012

The velocity field along the San Andreas Fault in central and southern California

The velocity field within a 100‐km‐broad zone centered on the San Andreas fault between the Mexican border and San Francisco Bay has been inferred from repeated surveys of trilateration networks in the 1973–1989 interval. The velocity field has the appearance of a shear flow that remains parallel to the local strike of the fault even through such major deflections as the big bend of the San Andreas fault in the Transverse Ranges of southern California. Across‐strike profiles of the fault‐parallel component of velocity exhibit the expected sigmoidal shape, whereas across‐strike profiles of the fault‐normal component of velocity are flat and featureless. No significant convergence upon the fault is observed even along the big bend sector of the fault. Simple dislocation models can explain most of the features of the observed velocity field, but those explanations are not unique. About 35 mm/yr of relative plate motion is accounted for within the span of the trilateration networks. Geologic studies indicate that the secular slip rate on the San Andreas fault is about 35 mm/yr. The agreement between these two estimates implies that most of the strain accumulation is elastic and will be recovered in subsequent earthquakes. The relative motion observed across the San Andreas fault (35 mm/yr) plus that observed across the Eastern California shear zone (8 mm/yr) accounts for most (43 mm/yr) of the observed North America‐Pacific relative plate motion (47 mm/yr).

California↗
USGS2015

Simulation of the effects of different inflows on hydrologic conditions in Lake Houston with a three-dimensional hydrodynamic model, Houston, Texas, 2009–10

Lake Houston, an important water resource for the Houston, Texas, area, receives inflows from seven major tributaries that compose the San Jacinto River Basin upstream from the reservoir. The effects of different inflows from the watersheds drained by these tributaries on the residence time of water in Lake Houston and closely associated physical and chemical properties including lake elevation, salinity, and water temperature are not well known. Accordingly, the U.S. Geological Survey (USGS), in cooperation with the City of Houston, developed a three-dimensional hydrodynamic model of Lake Houston as a tool for evaluating the effects of different inflows on residence time of water in the lake and associated physical and chemical properties. The Environmental Fluid Dynamics Code (EFDC), a grid-based, surface-water modeling package for simulating three-dimensional circulation, mass transport, sediments, and biogeochemical processes, was used to develop the model of Lake Houston. The Lake Houston EFDC model was developed and calibrated by using 2009 data and verified by using 2010 data. Three statistics (mean error, root mean square error, and the Nash-Sutcliffe model efficiency coefficient) were used to evaluate how well the Lake Houston EFDC model simulated lake elevation, salinity, and water temperature. The residence time of water in reservoirs is associated with various physical and chemical properties (including lake elevation, salinity, and water temperature). Simulated and measured lake-elevation values were compared at USGS reservoir station 08072000 Lake Houston near Sheldon, Tex. The accuracy of simulated salinity and water temperature values was assessed by using the salinity (computed from measured specific conductance) and water temperature at two USGS monitoring stations: 295826095082200 Lake Houston south Union Pacific Railroad Bridge near Houston, Tex., and 295554095093401 Lake Houston at mouth of Jack’s Ditch near Houston, Tex. Specific conductance and water temperature were measured at as many as four different depths at each of the two monitoring stations during 2009 and then used for assessing the accuracy of simulated values of salinity and water temperature during 2010. The performance evaluation statistics indicate that the model performed satisfactorily. The calibrated model was used to simulate two possible inflow scenarios to evaluate the changes in the residence time of water in Lake Houston. The two scenarios tested were an increased inflow of approximately 300 cubic feet per second for 1 month (May 2010) from two watersheds: the West Fork San Jacinto River and Luce Bayou. These scenarios were chosen to mimic the effects of possible small releases or diversions of water from outside the San Jacinto River Basin into the basin (or directly into the lake) on the residence time of water in Lake Houston. During the time of increased inflow for the two scenarios tested, maximum residence time decreased slightly from approximately 106 to 97 days.

Texas↗
USGS1976

Geologic appraisal of the petroleum potential of offshore southern California; the borderland compared to onshore coastal basins

Offshore southern California is part of a much larger Pacific continental margin, and the two areas have a similar geologic history at least as far back as middle Tertiary time. Assessment of the petroleum potential of the offshore Southern California borderland is accomplished by examining the adjacent highly explored productive coastal basins in the tectonically unstable area west of the San Andreas fault. Known oil and gas accumulations in this region can be characterized as follows: 88 percent comes from the Los Angeles and Ventura basins; 87 percent has been found in late Miocene and younger strata and only 0.2 percent has been found in Eocene strata; 80 percent has been found in thick deposits of deep-water turbidite reservoirs; and 5 percent has been found in fractured Miocene siliceous shale reservoirs. The percentage of siliceous shale reservoirs will increase as a result of recent discoveries in this rock type in the Santa Barbara Channel. Of the 212 known fields only 5 are giants (greater than 500 million barrels), and these fields account for 52 percent of all past production from the region. Most fields are faulted anticlines, and the largest fields have the highest oil recoveries per acre. Geologic knowledge of the offshore is limited by the availability of data. Data have been obtained from geophysical surveys, analyses of bedrock samples from the sea floor, and extrapolations of data from the mainland and offshore islands. Several factors have a negative effect on the assessment of the petroleum potential of the southern California borderland. They are: 1. The Neogene section is relatively thin, and the Paleogene section is thin and has a limited distribution. 2. Over large areas, Miocene sediments apparently rest directly on basement. 3. Along much of the Santa Rosa-Cortes Ridge, sediments are uplifted and truncated, exposing Paleogene rocks. 4. Organic content in Paleogene sediments is believed too low to generate large amounts of petroleum. 5. Source rocks are immature, even in sediments as old as Eocene. 6. Burial and thermal history are insufficient for the generaton of hydrocarbons over much of the borderland area. 7. Documented oil and gas seeps are unknown seaward of the Channel Islands. 8. Limited exploratory drilling nearshore, the best prospective area, has not been favorable. 9. Adequate or thick reservoirs of deep-water turbidire origin are not evident. These negative factors are partly offset by the following positive factors: 1. Miocene sediments are excellent potential source rocks. 2. Asphaltic oil in rocks of Monterey-type lithology may be generated at lower than normal temperatures. 3. Shallow-water sands of reservoir quality possibly are present in the uppermost Paleogene and lowermost Neogene section. 4. Potential structural traps may be analogous to major structural producing trends onshore. 5. Fractured shale reservoirs may be present along flanks of major banks and ridges. 6. Buried and unsampled Paleogene and Late Cretaceous sediments may be better source rocks than those sampled and measured. The southern California borderland, although a part of a locally rich petroliferous region, has no known basins with geologic histories or characteristics similar to the Los Angeles and Ventura basins. Some offshore basins are similar to less endowed basins in terms of petroleum potential such as the Santa Maria and Salinas basins. Areas with the best petroleum potential may be in deep water (greater than 500 m). Some of the past high estimates of the petroleum potential may have been overstated; the existing geologic data tend to substantiate low estimates of 0.6 to 5.8 billion barrels of oil and 0.6 to 5.8 trillion ft3 of gas for the southern California borderland at the 5 and 95 percent probability level.

Circular↗
USGS1975

Whitlockite and apatite of surficial phosphate occurrences on Enderbury Island, Phoenix Islands, Pacific Ocean

Whitlockite and apatite are the principal phosphate minerals in the surficial deposits of Enderbury Island; monetite and brushite are present in small amounts. All are derived from the guano of sea birds. The abundance of whitlockite discovered on Enderbury, and reported in samples from Remire Island in the Indian Ocean, indicates that the mineral is probably of common occurrence in young insular phosphate deposits. The composition of whitlockite from Enderbury Island is roughly (Ca, Mg, Sr, Na) 3 (PO 4 , CO 3 ) 2 , similar to the composition indicated for other insular occurrences by the sparse data available. The variety of apatite found on the island is carbonate fluor-hydroxylapatite, low in fluorine content. Whitlockite appears to have formed directly from guano components in surficial aqueous solutions, possibly accompanied by apatite, but changes with time to apatite.

Enderbury Island, Phoenix Islands↗