Managing Forest Road Removal Using Dynamic Programming: A Pilot Study

This U.S. Geological Survey (USGS) data release provides the descriptions of 11 U.S. sites that include mineral regions, mines, and mineral occurrences that contain enrichments of niobium (Nb). To be included in this data release, a site must have a contained resource and (or) past production of Nb metal greater than 10,000 metric tons, which was the approximate consumption of Nb in the U.S. in 2019 (U.S. Geological Survey, 2020). Sites in this dataset occur in Alaska, Arkansas, Colorado, Nebraska, and Texas. Niobium primarily occurs in oxide minerals of the pyrochlore group, which are most commonly found in carbonatites and alkaline granite-syenite complexes. Globally, the largest Nb deposits occur in Brazil and Canada. In Brazil, the Barreiro carbonatite complex hosts the Araxa deposit that contains more than 460 million metric tons of ore with an average grade of 2.48 percent Nb2O5 (Schulz and others, 2017). The world’s leading producer of Nb outside of Brazil is the Niobec Mine in Quebec, Canada. The Niobec deposit occurs in the Saint-Honore carbonatite complex, where pyrochlore is the main niobium-bearing mineral; the ore body contains more than 400 million metric tons with an average grade of 0.42 percent Nb2O5 (Schulz and others, 2017). In comparison, the largest known Nb deposit in the U.S. is the Iron Hill deposit in Colorado, which has been prospected for titanium, Nb, rare earth elements and thorium. There are no current U.S. producers of Nb, but the Elk Creek project in Nebraska is in the furthest stage of development. If Elk Creek comes online, it will be the first recorded producer of Nb in the U.S. since the 1950s. Niobium is necessary for strategic, consumer, and commercial applications. The primary use for Nb is for the production of high strength steel alloys used in pipelines, transportation infrastructure, and structural applications (Schulz and others, 2017). As of 2019, the U.S. maintains a history of being 100 percent net import reliant on Nb from countries, such as Brazil and Canada. Niobium is imported to the U.S. as Nb minerals, oxides, and ferroniobium (U.S. Geological Survey, 2020). The entries and descriptions in the database were derived from published papers, reports, data, and internet documents representing a variety of sources, including geologic and exploration studies described in State, Federal, and industry reports. Resources extracted from older sources might not be compliant with current rules and guidelines in minerals industry standards, such as National Instrument 43-101 (NI 43-101). The inclusion of a Nb mineral deposit in this database is not meant to imply that the deposit is currently economic. Rather, these deposits were included to capture the characteristics of the largest Nb deposits in the United States. Inclusion of material in the database is for descriptive purposes only and does not imply endorsement by the U.S. Government. The authors welcome additional published information in order to continually update and refine this dataset. Schulz, K.J., Piatak, N.M., and Papp, J.F., 2017, Niobium and tantalum, chap. M of Schulz, K.J., DeYoung, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply: U.S. Geological Survey Professional Paper 1802, p. M1–M34, https://doi.org/10.3133/pp1802M. U.S. Geological Survey, 2020, Mineral commodity summaries 2020: U.S. Geological Survey, 200 p., https://doi.org/10.3133/mcs2020.

Introduction Site selection Bacteriological sampling sites Water-quality sampling sites Sample collection and analysis methods Bacteriological samples Water-quality samples Quality-assurance procedures Bacteriological sample processing and analysis Water-quality sample processing and analysis Results Bacteriological results Water-quality results

<p>The increasing stress on water resource systems has prompted researchers to look for ways to improve the performance of reservoir operations. Changes in demand, various hydrological inputs, and new environmental stresses are among issues that water managers face. These concerns have sparked interest in applying different techniques to determine reservoir operation policy to improve reservoir system performance. As the resolution of analysis rises, it becomes more difficult to effectively represent a real-world system using currently available approaches for determining the best reservoir operation policy. One of the challenges is the "curse of dimensionality," which occurs when the discretization of the state and action spaces becomes finer or when more state or action variables are taken into account. Because of the dimensionality curse, the number of state-action variables is limited, rendering dynamic programming (DP) and stochastic DP (SDP) ineffective in handling complex reservoir optimization issues. Reinforcement learning (RL) is one way to overcome the aforementioned curses of stochastic optimization of water resources systems. RL is a well-known and influential technique in machine learning research that can solve a wide range of optimization and simulation challenges. In this study, a novel continuous-action deep RL algorithm called Deep Deterministic Policy Gradients (DDPG) is applied to solve the DP problem for the Folsom Reservoir system located in California, US. Without requiring any model simplifications or surrendering any of the critical characteristics of DP, the employed continuous action-space RL method effectively overcomes dimensionality concerns. The system model employs an iterative learning method that takes into account delayed rewards without requiring an explicit probabilistic model of hydrologic processes, and it can learn the best actions that maximize total expected reward by interacting with a simulated environment. This research is funded by the US Geological Survey.</p>

First posted September 28, 2016 For additional information, contact: Director, Fort Collins Science CenterU.S. Geological Survey2150 Centre Ave., Bldg. CFort Collins, CO 80526-8118http://www.fort.usgs.gov/ This is the eighth annual report highlighting U.S. Geological Survey (USGS) science and decision-support activities conducted for the Wyoming Landscape Conservation Initiative (WLCI). The activities address specific management needs identified by WLCI partner agencies. In 2015, USGS scientists continued 24 WLCI projects in 5 categories: (1) acquiring and analyzing resource-condition data to form a foundation for understanding and monitoring landscape conditions and projecting changes; (2) using new technologies to improve the scope and accuracy of landscape-scale monitoring and assessments, and applying them to monitor indicators of ecosystem conditions and the effectiveness of on-the-ground habitat projects; (3) conducting research to elucidate the mechanisms that drive wildlife and habitat responses to changing land uses; (4) managing and making accessible the large number of databases, maps, and other products being developed; and (5) coordinating efforts among WLCI partners, helping them to use USGS-developed decision-support tools, and integrating WLCI outcomes with future habitat enhancement and research projects. Of the 24 projects, 21 were ongoing, including those that entered new phases or more in-depth lines of inquiry, 2 were new, and 1 was completed.A highlight of 2015 was the WLCI science conference sponsored by the USGS, Bureau of Land Management, and National Park Service in coordination with the Wyoming chapter of The Wildlife Society. Of 260 participants, 41 were USGS professionals representing 13 USGS science centers, field offices, and Cooperative Wildlife Research Units. Major themes of USGS presentations included using new technologies for developing more efficient research protocols for modeling and monitoring natural resources, researching effects of energy development and other land uses on wildlife species and habitats of concern, and modeling species distributions, population trends, habitat use, and effects of land-use changes. There was also a special session on the effectiveness of Wyoming’s Sage-Grouse Executive Order. Combined, USGS presentations provided WLCI partners with a wealth of information and conservation tools.The project completed in 2015 yielded an index of important agricultural lands in the WLCI region. The index improves upon existing measures of agricultural productivity and provides planners and managers with additional values to consider when making decisions about land use and conservation actions. The two new projects include an analysis of satellite imagery to quantify sagebrush productivity and mortality, and an evaluation of how groundwater and small streams interact in the upper Green River Basin. Initiated in response to concern among WLCI partners that large areas of sagebrush appear to have died recently, the sagebrush study objectives are to assess effects of these mortality events on overall sagebrush ecosystem productivity, evaluate the feasibility of using satellite imagery to detect patterns in sagebrush mortality over time, and identify factors driving these mortality events. The groundwater-streamflow interaction study is being conducted by hydrologists and fish ecologists to better understand how groundwater-streamflow interactions are affected by energy-resource development and how native fish communities are affected by these factors. Expected outcomes of both new projects will provide WLCI partners with additional information and decision-support tools.Highlights of ongoing science foundation activities included simulations of nine alternative build-out scenarios for oil and gas development and an associated online fact sheet that explains how the simulations were conducted, with an applied example for the Atlantic Rim. Also completed in 2015 was an update of the USGS online inventory of mineral resources data, and publication of a USGS uranium resource survey for the WLCI region. Combined, the outcomes of this work provide decisionmakers and managers with important baseline information for existing and (or) future planning and monitoring efforts.Terrestrial monitoring activities in 2015 emphasized the use of satellite data in combination with other technologies and field data to monitor, assess, and (or) forecast distribution patterns and (or) trends in sagebrush ecosystems, seasonal and migration stopover habitats used by mule deer and elk, and semi-arid aspen woodlands. Several professional papers detailing new monitoring models and results have been published. Combined, this and related work will help managers understand distribution patterns and trends among priority habitats, identify areas in need of restoration or conservation, and monitor the effectiveness of habitat-management actions.Aquatic monitoring activities entailed not only the new groundwater-streamflow interaction study already mentioned, but also continued monitoring with streamgages paired with nearby wells in the Green River Basin to assess groundwater effects on streamflow and surface water temperatures. A map that portrays groundwater levels and general direction of flow in the Green River Basin was published as well. Overall, outcomes of USGS hydrological research and monitoring will inform WLCI partners about water resources in the WLCI region and help to explain fish-community responses to energy-resource development.In 2015, USGS terrestrial wildlife ecologists continued to make crucial strides towards better understanding wildlife species responses to energy-resource development and other land-use changes. This body of research includes six taxa that require or heavily depend on sagebrush habitats: sage-grouse, pygmy rabbits, 3 songbird species, and mule deer. Native fish communities are also being evaluated. Approaches include modeling and mapping wildlife species distributions, abundances, and trends; using satellite and other technologies to track wildlife seasonal movements; conducting successive phases of research that build on the knowledge gained through prior phases to reveal the specific factors or thresholds that drive population- or individual-level responses to changes; and conducting population viability analyses. Additionally, wildlife habitat association models for pygmy rabbit and sage-grouse were combined with the oil and gas build-out scenarios to project species responses to alternative energy development scenarios. Outcomes of the wildlife response research are helping decisionmakers and managers identify specific factors that contribute to species population trends, the potential for spatial overlap between important wildlife habitats and proposed energy-resource development, locations of priority habitats for restoration and conservation, and more.Data and WLCI Web site management highlights of 2015 included not only ongoing software upgrades, but also an update of the datasets displayed in two of the online products developed for the WLCI effort: (1) a map of 15,532 oil and natural gas well pad scars and other features associated with oil and gas extraction, and (2) a map of oil and gas, oil shale, uranium, and solar energy production, both for southwestern Wyoming. In addition, a map viewer was developed for a previously published map of coal and wind production in relation to sage-grouse distribution and core management areas in southwestern Wyoming. Combined, these maps place valuable decision-support tools in the hands of WLCI partners.The USGS coordination efforts on behalf of the WLCI in 2015 included significant work on planning and executing the WLCI science conference. They also included ongoing efforts to support Local Project Development Teams and the WLCI Coordination Team (CT) with developing conservation priorities and strategies, identifying priority areas for future conservation actions, supporting the evaluation and ranking of conservation projects, and evaluating the ways in which proposed habitat projects relate to WLCI priorities. In 2015, the USGS also assisted the WLCI CT with updating the WLCI Conservation Action Plan.

Since 2003, the U.S. Geological Survey (USGS) Oklahoma Water Science Center has been using the USGS well profiler to characterize changes in water contribution and contaminant concentrations with depth in pumping public-supply wells in selected aquifers (fig. 1). The tools and methods associated with the well profiler, which were first developed by the USGS California Water Science Center (Izbicki and others, 1999), have been used to investigate common problems such as saline water intrusion in high-yield irrigation wells (Izbicki and others, 2005) and metals contamination in highyield public-supply wells (Ball and Izbicki, 2004). The USGS well profiler (fig. 2) is a slim (less than 1 inch in diameter), high-pressure hose that can be raised and lowered between the production pipe and casing (or borehole) of a well by using a motorized hose reel. Use of this tool is considerably less expensive than use of standard methods of depth-dependent sampling, and the USGS well profiler generally requires less downtime of the well. In terms of data quality, the greatest advantage of the USGS well profiler is that all data collection is performed under production pumping rates. In Oklahoma, the USGS well profiler has been modified and adapted for use in low-yield (150–350 gallons per minute) wells of various construction types common in Oklahoma. This tool has been used in selected public-supply wells in Hinton, Moore, and Norman to identify which producing zones are contaminated by naturally occurring arsenic (fig. 1). The tool and method also can be used to investigate other nonvolatile contaminants of interest, including uranium, radium, barium, boron, lead, selenium, sulfate, chloride, fluoride, nitrate, and chromium. In 2007, the USGS well profiler was used to investigate saline water intrusion in a deep public-supply well completed in the Ozark (Roubidoux) aquifer (Pope and others, 2009; fig. 1). In northeast Oklahoma, where the Ozark aquifer is known to be susceptible to contamination from mining activities (Christenson, 1995), the well profiler also could be used to investigate sources (depths) of metals contamination and to identify routes of entry of metals to production wells. Water suppliers can consider well rehabilitation as a potential remediation strategy because of the ability to identify changes in contaminant concentrations with depth in individual wells with the USGS well profiler. Well rehabilitation methods, which are relatively inexpensive compared to drilling and completing new wells, involve modifying the construction or operation of a well to enhance the production of water from zones with lesser concentrations of a contaminant or to limit the production of water from zones with greater concentrations of a contaminant. One of the most effective well rehabilitation methods is zonal isolation, in which water from contaminated zones is excluded from production through installation of cement plugs or packers. By using relatively simple and inexpensive well rehabilitation methods, water suppliers may be able to decrease exposure of customers to contaminants and avoid costly installation of additional wells, conveyance infrastructure, and treatment technologies.

The State of Alaska's Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska's statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. For this report, DGGS funded reanalysis of 1,682 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from an area covering Kougarok area, Bendeleben and Teller quadrangles, Seward Peninsula, Alaska. USGS was responsible for sample retrieval from the Denver warehouse through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated into the statewide geochemical databases of both agencies.

The State of Alaska's Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska's statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. For this report, DGGS funded reanalysis of 1,682 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from an area covering Inmachuk, Kugruk, Kiwalik, and Koyuk River drainages, Granite Mountain, and the northern Darby Mountains, Bendeleben, Candle, Kotzebue, and Solomon quadrangles, Alaska. USGS was responsible for sample retrieval from the Denver warehouse through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated into the statewide geochemical databases of both agencies.

A 1:62,500-scale black-and-white map identifying some 2,000 landslides of various types in Santa Cruz County, California, has been converted to a digital-map database that can be acquired from the U.S. Geological Survey over the Internet or on magnetic tape. PREFACE The effort toward a landslide inventory of Santa Cruz County began about 1972 when Walter Monasch, then Planning Director for the county, saw a landslide inventory and other hazard maps prepared for San Mateo County as part of a pilot program underway by the U.S. Geologic Survey (USGS) for the nine counties surrounding San Francisco Bay. He asked if the USGS would prepare similar maps for his county so that he could respond to a new State of California requirement that geologic hazards be considered in the seismic safety element of the general plan for all cities and counties. When informed that the USGS did not have the manpower to comply with his request, he asked if the USGS would supervise the work of consultants to prepare a landslide inventory, a fault map, and a map showing areas that might liquefy during an earthquake− providing that the County fund this project. The USGS agreed to find the consultants to do the work. N. Timothy Hall was engaged to prepare the fault map, William Dupre the liquefaction map, and Cooper-Clark and Associates the landslide inventory. Earl E. Brabb was assigned by the USGS to monitor the work. All of the finished maps were added to the seismic safety element of the general plan adopted by the Santa Cruz County Board of Supervisors on August 26, 1975. The formal citation for the landslide map is: Cooper-Clark and Associates, 1975, Preliminary map of landslide deposits in Santa Cruz County, CA, Planning Department, 1 sheet, map scale 1:62,500. Although the information in this database has not been updated or amended beyond that in Cooper-Clark and Associates (1975), it is being released in digital form because it is the only systematic landslide-inventory that exists for Santa Cruz County. Users are cautioned that these 25to 30-year-old data have shortcomings in addition to the several caveats cited in the original map text. Information on the slope-failure hazard is incomplete. Landslides occurring in the County after 1970 (date of the latest airphotos used in the 1975 compilation), particularly during the severe winters of 1982 (15 fatalities; Cotton, 1982), 1983, and 1998, are not recorded here.

Topicality. The paper discusses the possibility of using modern GIS technologies for studying coastal ecosystems of the Azov-Black Sea basin within the framework of blue growth. Today, GIS technologies greatly facilitate the study of the impact of natural and anthropogenic factors on the natural environment. The development of these technologies has increased greatly in recent decades. Now they can be used as a separate and independent tool for research in various areas of production. Based on the results obtained on the basis of GIS technologies, it is possible to draw scientific conclusions or create and implement management decisions to maintain sustainable or resilient development of the state of the environment under significant environmental pressure. Also conduct an economic, environmental, social assessment of the consequences of anthropogenic and natural impacts on marine and coastal ecosystems and the terrestrial ecosystem.Aim and tasks. Scientific substantiation of the possibilities of using modern GIS technologies regarding the sustainable development of the coastal ecosystem of the Azov-Black Sea basin within the framework of blue growth was the aim of the study.Materials and Methods. The studies were based on coastal mapping methods. The classification of environmental parameters based on United States Geological Survey (USGS) data was the initial information. The ecological coastal classification (Ecological Coastal Units (ECU)) was developed by the US Geological Survey (USGS) in collaboration with Esri and the Marine Biodiversity Observation Network (MBON). These data were developed as part of a Group on Earth Observation (GEO) initiative called GEO Ecosystems (GEO ECO). They are linked to the GEO ECO task of developing global data on coastal ecosystems.Research results. The state of the coastal strip of the seas of Ukraine according to the classification of environmental parameters based on data from the United States Geological Survey (USGS) was described in this paper. It was stated that the ecological status of coastlines is classified into five ocean parameters, two land parameters and three coastal parameters. The research results showed that the ecological situation of the coastal strips of the seas of Ukraine generally corresponds to the second, third, sixth and fifteenth classes according to the ecological coastal classification.Conclusion. It is presented that the coastal strip classification method discussed in this paper based on US Geological Survey (USGS) data can serve as a very powerful tool in the process of managing coastal zones of the Azov-Black Sea basin. It has been established that GIS technologies at the current stage of development have very great potential for studying coastal ecosystems of the Azov-Black Sea basin within the framework of blue growth.

The U. S. Geological Survey (USGS) initiated the Requirements, Capabilities and Analysis for Earth Observations (RCA-EO) activity in the Land Remote Sensing (LRS) program to provide a structured approach to collect, store, maintain, and analyze user requirements and Earth observing system capabilities information. RCA-EO enables the collection of information on current key Earth observation products, services, and projects, and to evaluate them at different organizational levels within an agency, in terms of how reliant they are on Earth observation data from all sources, including spaceborne, airborne, and ground-based platforms. Within the USGS, RCA-EO has engaged over 500 subject matter experts in this assessment, and evaluated the impacts of more than 1000 different Earth observing data sources on 345 key USGS products and services. This paper summarizes Landsat impacts at various levels of the organizational structure of the USGS and highlights the feedback of the subject matter experts regarding Landsat data and Landsat-derived products. This feedback is expected to inform future Landsat mission decision making. The RCA-EO approach can be applied in a much broader scope to derive comprehensive knowledge of Earth observing system usage and impacts, to inform product and service development and remote sensing technology innovation beyond the USGS.

Quantifying form resistance is essential for estimating summer low and bankfull flow from stream survey channel morphology

Of all the potential threats posed by climatic variability and change, those associated with water resources are arguably the most consequential for both society and the environment (Waggoner, 1990). Climatic effects on agriculture, aquatic ecosystems, energy, and industry are strongly influenced by climatic effects on water. Thus, understanding changes in the distribution, quantity and quality of, and demand for water in response to climate variability and change is essential to planning for and adapting to future climatic conditions. A central role of the U.S. Geological Survey (USGS) with respect to climate is to document environmental changes currently underway and to develop improved capabilities to predict future changes. Indeed, a centerpiece of the USGS role is a new Climate Effects Network of monitoring sites. Measuring the climatic effects on water is an essential component of such a network (along with corresponding effects on terrestrial ecosystems). The USGS needs to be unambiguous in communicating with its customers and stakeholders, and with officials at the Department of the Interior, that although modeling future impacts of climate change is important, there is no more critical role for the USGS in climate change science than that of measuring and describing the changes that are currently underway. One of the best statements of that mission comes from a short paper by Ralph Keeling (2008) that describes the inspiration and the challenges faced by David Keeling in operating the all-important Mauna Loa Observatory over a period of more than four decades. Ralph Keeling stated: 'The only way to figure out what is happening to our planet is to measure it, and this means tracking changes decade after decade and poring over the records.' There are three key ideas that are important to the USGS in the above-mentioned sentence. First, to understand what is happening requires measurement. While models are a tool for learning and testing our understanding, they are not a substitute for observations. The second key idea is that measurement needs to be done over a period of many decades. When viewing hydrologic records over time scales of a few years to a few decades, trends commonly appear. However, when viewed in the context of many decades to centuries, these short-term trends are recognized as being part of much longer term oscillations. Thus, while we might want to initiate monitoring of important aspects of our natural resources, the data that will prove to be most useful in the next few years are those records that already have long-term continuity. USGS streamflow and groundwater level data are excellent examples of such long-term records. These measured data span many decades, follow standard protocols for collection and quality assurance, and are stored in a database that provides access to the full period of record. The third point from the Keeling quote relates to the notion of ?poring over the records.? Important trends will not generally jump off the computer screen at us. Thoughtful analyses are required to get past a number of important but confounding influences in the record, such as the role of seasonal variation, changes in water management, or influences of quasi-periodic phenomena, such as El Ni?o-Southern Oscillation (ENSO) or the Pacific Decadal Oscillation (PDO). No organization is better situated to pore over the records than the USGS because USGS scientists know the data, quality-assure the data, understand the factors that influence the data, and have the ancillary information on the watersheds within which the data are collected. To fulfill the USGS role in understanding climatic variability and change, we need to continually improve and strengthen two of our key capabilities: (1) preserving continuity of long-term water data collection and (2) analyzing and interpreting water data to determine how the Nation's water resources are changing. Understanding change in water resources

This report describes the bacteriological results of a ground-water study conducted from 1993 to 1995 as part of the U.S. Geological Survey's National Water-Quality Assessment Program in the Lower Susquehanna River Basin study unit. Water samples collected from 146 household supply wells were analyzed for fecal-indicator organisms including total coliform, fecal coliform, Escherichia coli (E. coli), and fecal streptococcus concentrations. Supporting data used in the interpretations are selected water-quality constituents, wellconstruction information, and the environmental setting at the well site including land use, physiography, and bedrock type. Water from nearly 70 percent of the wells sampled had total coliform present and thus was not suitable for drinking without treatment. Fecal coliforms were found in water from approximately 25 percent of the sampled wells, f. coli testing was not conducted in 1993. Approximately 30 percent of the 88 sampled wells had waters with f. coli. Fecal streptococcus bacteria was present in water from about 65 percent of the wells sampled. Bacteriological contamination was more likely to occur in water from wells in agricultural areas than in water from wells in forested areas. Water from wells sampled in the Ridge and Valley Physiographic Province was more likely to have bacteria than water from wells in the Piedmont Physiographic Province. Differences in bacterial concentrations among bedrock types are only statistically significant for E. coli. Bacterial concentrations are weakly related to well-age but not to other well characteristics such as the total well depth or the casing length. Relations exist between bacterial concentrations and selected water-quality constituents. Most wells from which water was sampled did not have sanitary seals and very few were grouted. This may have contributed to the number of detections of bacteria. It is uncertain whether the bacteria detected are the result of widespread aquifer contamination or sitespecific factors. NATIONAL WATER-QUALITY ASSESSMENT PROGRAM INTRODUCTION The U.S. Geological Survey's (USGS) National Water-Quality Assessment (NAWQA) Program is designed to determine the occurrence and distribution of water-quality characteristics in ground water and surface water (Gilliom and others, 1995). Studies began in 1991 in the Lower Susquehanna River Basin study unit, hereafter termed the study unit. The occurrence and distribution of bacteria in ground water are important water-quality issues in the study unit. Ground water is an important source of household supply in the study unit. Private water-supply information from the U.S. Bureau of the Census (1990) for counties in the study unit shows a total of nearly 1,600,000 households, of which about 500,000 depend on ground water from private wells for their drinking water supply (table 1). Approximately 400,000 households are in Pennsylvania; the others are in Maryland. Because only parts of some counties are within the basin, these numbers overrepresent the number of households and private wells in the basin (table 1). To estimate the number of households and private wells, the number in each county was multiplied by the fraction of each county in the basin. Using this estimation, about 800,000 households and approximately 300,000 private wells are in the basin. Therefore, approximately 38 percent of the households in the study unit depend on ground water from private wells for water supply. Table 1. Private water-supply information from the 1990 U.S. Bureau of the Census for counties in the Lower Susquehanna River Basin study unit

Ultrasound Elastography is an emerging imaging technique that allows estimation of the mechanical characteristics of tissue. Two issues that need to be addressed before widespread use of elastography in clinical environments are real time constraints and deteriorating effects of signal decorrelation between pre- and post-compression images. Previous work has used Dynamic Programming (DP) to estimate tissue deformation. However, in case of large signal decorrelation, DP can fail. In this paper we, have proposed a novel solution to this problem by solving DP on a tree instead of a single Radio-Frequency line. Formulation of DP on a tree allows exploiting significantly more information, and as such, is more robust and accurate. Our results on phantom and in-vivo human data show that DP on tree significantly outperforms traditional DP in ultrasound elastography.

During fiscal years 1990-92, the water-resources activities of the U.S. Geological Survey in Louisiana consisted of hydrologic data collection and interpretive investigations and research. Data collection activities involved the operation of statewide stream gaging, ground-water, and quality-of-water long-term monitoring networks. Interpretive investigations and research addressed specific hydrologic concerns such as potential organic chemical contamination in the lower Calcasieu River, water quality of the Barataria basin and Mermentau River basin, water quality and flood characteristics of streams, quality and quantity of freshwater in aquifers, and evaluation of ground-water resources. This report briefly describes the problem, objective, approach, progress, and plans for each project. It also includes a description of the District's organization and a list of cooperators.