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At least 325 records · Page 18Linked to original sources

Overview--Development of a geodatabase and conceptual model of the hydrogeologic units beneath Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

Air Force Plant 4 (AFP4) and adjacent Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB) at Fort Worth, Tex., constitute a contractor-owned, government-operated facility that has been in operation since 1942. Contaminants from the 3,600-acre facility, primarily volatile organic compounds (VOCs) and metals, have entered the ground-water-flow system through leakage from waste-disposal sites and from manufacturing processes. Environmental data collected at AFP4 and NAS–JRB during 1993–2002 created the need for consolidation of the data into a comprehensive temporal and spatial geodatabase. The U.S. Geological Survey (USGS), in cooperation with the U.S. Air Force Aeronautical Systems Center Environmental Management Directorate, developed a comprehensive geodatabase of temporal and spatial environmental data associated with the hydrogeologic units beneath the facility. A three-dimensional conceptual model of the hydrogeologic units integrally linked to the geodatabase was designed concurrently. Three hydrogeologic units—from land surface downward, the alluvial aquifer, the GoodlandWalnut confining unit, and the Paluxy aquifer—compose the subsurface of interest at AFP4 and NAS–JRB. The alluvial aquifer consists primarily of clay and silt with sand and gravel channel deposits that might be interconnected or interfingered. The Goodland-Walnut confining unit directly underlies the alluvial aquifer and consists of limestone, marl, shale, and clay. The Paluxy aquifer is composed of dense mudstone and fine- to coarse-grained sandstone

Texas

Assessment of selected inorganic constituents in streams in the Central Arizona Basins study area, Arizona and northern Mexico, through 1998

Stream properties and water-chemistry constituent concentrations from data collected by the National Water-Quality Assessment and other U.S. Geological Survey water-quality programs were analyzed to (1) assess water quality, (2) determine natural and human factors affecting water quality, and (3) compute stream loads for the surface-water resources in the Central Arizona Basins study area. Stream temperature, pH, dissolved-oxygen concentration and percent saturation, and dissolved-solids, suspended-sediment, and nutrient concentration data collected at 41 stream-water quality monitoring stations through water year 1998 were used in this assessment. Water-quality standards applicable to the stream properties and water-chemistry constituent concentration data for the stations investigated in this study generally were met, although there were some exceedences. In a few samples from the White River, the Black River, and the Salt River below Stewart Mountain Dam, the pH in reaches designated as a domestic drinking water source was higher than the State of Arizona standard. More than half of the samples from the Salt River below Stewart Mountain Dam and almost all of the samples from the stations on the Central Arizona Project Canal—two of the three most important surface-water sources used for drinking water in the Central Arizona Basins study area—exceeded the U.S. Environmental Protection Agency drinking water Secondary Maximum Contaminant Level for dissolved solids. Two reach-specific standards for nutrients established by the State of Arizona were exceeded many times: (1) the annual mean concentration of total phosphorus was exceeded during several years at stations on the main stems of the Salt and Verde Rivers, and (2) the annual mean concentration of total nitrogen was exceeded during several years at the Salt River near Roosevelt and at the Salt River below Stewart Mountain Dam. Stream properties and water-chemistry constituent concentrations were related to streamflow, season, water management, stream permanence, and land and water use. Dissolved-oxygen percent saturation, pH, and nutrient concentrations were dependent on stream regulation, stream permanence, and upstream disposal of wastewater. Seasonality and correlation with streamflow were dependant on stream regulation, stream permanence, and upstream disposal of wastewater. Temporal trends in streamflow, stream properties, and water-chemistry constituent concentrations were common in streams in the Central Arizona Basins study area. Temporal trends in the streamflow of unregulated perennial reaches in the Central Highlands tended to be higher from 1900 through the 1930s, lower from the 1940s through the 1970s, and high again after the 1970s. This is similar to the pattern observed for the mean annual precipitation for the Southwestern United States and indicates long-term trends in flow of streams draining the Central Highlands were driven by long-term trends in climate. Streamflow increased over the period of record at stations on effluent-dependent reaches as a result of the increase in the urban population and associated wastewater returns to the Salt and Gila Rivers in the Phoenix metropolitan area and the Santa Cruz River in the Tucson metropolitan area. Concentrations of dissolved solids decreased in the Salt River below Stewart Mountain Dam and in the Verde River below Bartlett Dam. This decrease represents an improvement in the water quality and resulted from a concurrent increase in the amount of runoff entering the reservoirs. Stream loads of water-chemistry constituents were compared at different locations along the streams with one another, and stream loads were compared to upstream inputs of the constituent from natural and anthropogenic sources to determine the relative importance of different sources and to determine the fate of the water-chemistry constituent. Of the dissolved solids transported into the Basin and Range Lowlands each year from the Central Arizona Project Canal and from streams draining the Central Highlands, about 1.2 billion kilograms accumulated in the soil, unsaturated zone, and aquifers in agricultural and urban areas as a result of irrigating crops and urban vegetation. Stream loads of phosphorus decreased from the 91st Avenue Wastewater-Treatment Plant downstream to the Gila River at Gillespie Dam, probably as a result of adsorption of phosphorus to the streambed sediments. In this same reach, stream loads of nitrogen increased, most likely because of inputs from fertilizers. The annual mass of nitrogen and phosphorus input to developed basins from quantifiable sources was much larger than the mass input to basins that had little or no municipal or agricul-tural development. These computed inputs exclude the mass of nitrogen and phosphorus from sources such as geologic formations and soils that could not be quantified. The quantifiable annual inputs of nitrogen and phosphorus for the upper Salt River Basin and the upper Verde River Basin were similar to those for the West Clear Creek Basin. This similarity suggests that the small amount of municipal and agricultural development in the upper Salt River and the upper Verde River Basins did not greatly change the basin input flux. For basins with minimal urban and agricultural development, the largest quantifiable source of nitrogen was precipitation, and the largest source of phosphorus was human bodily waste treated by sewer and septic systems. This was in contrast to developed basins, for which fertilizer was the largest quantifiable source of both nutrients. For most basins examined, quantifiable inputs of nitrogen and phosphorus from nonpoint sources were greater than inputs from point sources. This relation emphasizes the importance of land- and water-management policies that protect surface-water resources from nonpoint sources of nutrients as well as from point sources. The amount of nitrogen and phosphorus transpor-ted out of basins was a small fraction of the total for the quantifiable inputs. This result indicated that most of the nutrients input to basins were not transported out of the basins in surface water, but rather were transported to the subsurface (the soil, unsaturated zone, or aquifer), released to the atmosphere (such as volatilized ammonia), or incorporated into the biomass.

Central Arizona Basins study area

A community-based research approach to develop Chronic Wasting Disease outreach with Tribal communities

Chronic Wasting Disease (CWD) is a fatal and contagious neurological disease of cervid populations across North America. Collaborative efforts between government agencies, researchers, policymakers, and stakeholders are necessary to minimize CWD prevalence, spread, and impacts on animal and human health and well-being. However, critical information related to CWD epidemiology, management, and animal and human health risks was not effectively reaching Tribal Nations and their members. To understand these gaps and specific information needs and ensure meaningful participation in CWD management and control efforts, university researchers and Tribal members partnered to conduct semi-structured interviews that focused on deer hunting and the perceived impacts of CWD on Tribal communities. Interviews provided insights into information preferences, knowledge gaps, and perspectives on CWD, revealing a strong sense of responsibility toward deer and the environment. From this collaborative approach, we can create culturally tailored educational resources that address CWD concerns and align with Tribal values.

Michigan, Minnesota, Wisconsin

Development of a consortium for water security and safety: Planning for an early warning system

The events of September 11, 2001 have raised concerns over the safety and security of the Nation's critical infrastructure including water and waste water systems. In June 2002, the U.S. EPA's Region II Office (New York City), in response to concerns over water security, in collaboration with Rutgers University agreed to establish a Regional Drinking Water Security and Safety Consortium (RDWSSC). Members of the consortium include: Rutgers University's Center for Information Management, Integration and Connectivity (CIMIC), American Water (AW), the Passaic Valley Water Commission (PVWC), the North Jersey District Water Supply Commission (NJDWSC), the N.J. Department of Environmental Protection, the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agencies, Region II Office. In December of 2002 the consortium members signed a memorandum of understanding (MOU) to pursue activities to enhance regional water security. Development of an early warning system for source and distributed water was identified as being of primary importance by the consortium. In this context, an early warning system (EWS) is an integrated system of monitoring stations located at strategic points in a water utilities source waters or in its distribution system, designed to warn against contaminants that might threaten the health and welfare of drinking water consumers. This paper will discuss the consortium's progress in achieving these important objectives.

Conference Paper

Widespread landslide activity in an extreme wet season and implications for regional sediment management, eastern San Francisco Bay area, California

Watershed sediment production is expected to increase in a warmer future with more extreme rain, with cascading effects throughout drainage and sediment-transport networks. This study investigated landscape-scale sediment movement in the eastern San Francisco Bay area, California, USA, during the extreme 2016–2017 wet season that brought major rainfall, landslides, and flooding. Mapping 8,928 landslides across a 1,050-km 2 study area revealed new sediment yield of 510–956 t/km 2 , equivalent to denudation of 193–361 mm/ky. These results correspond closely to long-term denudation rates in the northern and central California Coast Ranges, indicating that mass wasting in very wet years dominates long-term sediment mobilization. However, due to long residence times in drainage networks, the 2017 landslides contributed at most ∼1%–2% of the estimated locally derived fluvial sediment transport to San Francisco Bay. Although the amount of sediment mobilized did not threaten municipal water supplies, small rangeland impoundments in this mixed-use landscape lost storage capacity to new sedimentation. Considering regional sediment supply and demand, even the exceptionally large sediment delivery in an extreme wet year cannot meet the need for sediment to accrete tidal wetlands in the bay. To keep pace with rising sea levels, this abnormally high terrestrial sediment input would need to occur in 50 of the next 75 years, an unlikely occurrence due to the prevalence of recent drought years. Shoreline protection and restoration in the bay would need additional sources of sediment, such as through management of dredged sediment through beneficial-reuse programs.

California

Sediment-transport investigations of the upper Yellowstone River, Montana, 1999 through 2001: Data collection, analysis, and simulation of sediment transport

The upper Yellowstone River in Montana is an important State and national water resource, providing recreational, agricultural, and commercial benefits. Floods in 1996 and 1997, with recorded peak discharges having recurrence intervals close to 100 years, caused substantial streambank erosion and hill- slope mass wasting. Large quantities of sand-, gravel-, and cobble-sized material entrained by the flood flows became flood-bar deposits, creating a source of sediment available for transport during future floods. The flood damage and resulting sedimentation raised concerns about potential streambank-stabilization projects and how the river and riparian corridor might be managed in the future. The U.S. Geological Survey, in cooperation with the Park Conservation District, the Montana Department of Transportation, and the U.S. Army Corps of Engineers, investigated sediment transport in the upper Yellowstone River near Livingston from 1999 through 2001 as part of a cumulative effects study to provide a scientific basis for future river management decisions. The purpose of this report is to present the results of data collection, analysis, and simulation of sediment transport for the upper Yellowstone River. The study area included a 13.5-mile study reach of the upper Yellowstone River where substantial sediment transport occurred in 1996 and 1997. In this study area, the upper Yellowstone River is a high gradient, coarse-bed stream having a slope of about 0.0028 foot per foot or more than 14 feet per mile. The study area drains about 3,551 square miles, and runoff results primarily from snowmelt during the spring and summer months. As part of sediment-transport investigations, the U.S. Geological Survey surveyed river cross sections, characterized streambed-material particle size using particle counts and sieve analyses, and collected bedload- and suspended-sediment data during three runoff seasons (1999-2001). Data were collected for stream discharges that ranged from 2,220 cubic feet per second (typical of pre- and post-runoff discharge) to 25,100 cubic feet per second (about 125 percent of bankfull discharge). The distribution of streambed-material particle size was determined, and sediment-transport curves for bedload discharge, suspended-sediment discharge, and total-sediment discharge were developed. The threshold values of streamflow and average stream velocity needed for initiation of bedload transport for selected sediment-size classes showed that little to no bedload was transported for an average stream velocity below about 3 feet per second, and the only particle size transported as bedload at that velocity was sand. Over the range of stream discharges sampled and with silt- and finer-sized particles excluded, bedload discharge averaged about 18 percent of the total-sediment discharge, equal to bedload discharge plus suspended-sediment discharge. At the lowest and highest stream discharges sampled, bedload was, respectively, less than about 2 percent and about 30 percent of the total-sediment discharge. Over the range of stream discharges sampled, the sand-sized part of the total suspended-sediment discharge averaged about 48 percent, where the total suspended-sediment discharge included sand-, silt- and finer-sized particles. At the lowest and highest stream discharges sampled, the sand-sized part of the total suspended-sediment discharge was, respectively, less than about 16 percent and about 50 percent of the total suspended-sediment discharge. The sediment-transport curves were compared to curves for selected sites in the western United States having drainage areas ranging from 21 square miles to over 20,000 square miles. Daily sediment loads transported at bankfull discharge were calculated for each site and results were plotted in relation to drainage area. Results based on the 1999-2001 data-collection period indicate that the estimated daily bedload transported at bankfull discharge in the upper Yellowstone River exceeded the envelope line that bounds the upper end of the data for other selected sites in the Northern Rocky Mountains and is similar in magnitude to that for selected sites in Alaska having braided channels and glacial and snowmelt runoff. Similar comparisons for suspended sediment indicate that daily suspended-sediment load at bankfull discharge is relatively high in the upper Yellowstone River, plotting slightly above the envelope line that bounds the upper end of the data for other selected sites in the Northern Rocky Mountains. Sediment data were used to develop individual transport equations for seven size classes of sediment ranging from small cobbles to very fine sand. A step-wise regression procedure relating sediment discharge to important hydraulic variables showed that average stream velocity was the only significant variable at the 95-percent confidence level. Bedload and suspended-sediment data and equations indicate that more sand is transported for a given velocity than any other particle size, and very little sand-size sediment load is transported below an average stream velocity of about 2.5 feet per second. Transport of coarser-sized sediment (limited to bedload) becomes very little for an average velocity less than about 3.5 feet per second. Results for the 1999-2001 data-collection period indicate that sediment transport in the upper Yellowstone River tends to be limited more by the transport capacity of the stream (capacity or transport limited), than to the availability of sediment in the watershed (supply limited). Sediment data collected and analyzed were used to simulate sediment transport in the study reach using the BRIdge Stream Tube model for Alluvial River Simulation, or BRI-STARS computer model. The model was calibrated and verified using selected data from historical runoff periods. Simulated total-sediment loads, on a reach-averaged basis, were in good agreement with the total-sediment loads determined from the transport curve for the 2-year flood hydrograph but were considerably smaller for the total-sediment loads determined from the transport curve for the 50-, 100-, and 500-year flood hydrographs. The differences probably were largely due to the inability of the model to simulate streambank erosion, hillslope mass-wasting, and other channel-widening processes, which had supplied substantial quantities of sediment to the channel during the 1996 and 1997 floods, and probably continued to contribute to the sediment load in the subsequent years (1999-2001) when the data were collected. Furthermore, the transport curve was applied beyond the measured data for the highest discharges, and may thus be unreliable. Also, the transport curve derived from only limited data may not apply over the full duration of the hydrograph and sediment might be transported over only a portion of the hydrograph, especially for rivers like the upper Yellowstone where snowmelt runoff predominates. The true sediment discharge is, therefore, unknown and might be closer to the simulated values than to the values calculated from the transport curve.

Montana

Water-quality characteristics and contaminants in the rural karst-dominated Spring Mill Lake watershed, southern Indiana

The Spring Mill Lake watershed is located in the Mitchell Plateau, a karst area that developed on Mississippian carbonates in southern Indiana. Spring Mill Lake is a reservoir built in the late 1930s and is located in Spring Mill State Park. Within the park, groundwater from subsurface conduits issues as natural springs and then flows in surface streams to the lake. From 1998 to 2002, surface and subsurface hydrology and water quality were investigated to determine the types and sources of potential contaminants entering the lake. Water samples collected during base flow and a February 2000 storm event were analyzed for selected cations, anions, trace elements, selected U.S. Environmental Protection Agency (EPA) primary and secondary drinkingwater contaminants, nitrogen isotopes, suspended solids, Escherichia coli, and pesticides. All of the water samples met the EPA drinking-water standards for inorganic constituents, except those collected at five sites in August 1999 during a drought. Nitrate nitrogen (NO 3 -N) concentrations were highest during base-flow conditions and displayed a dilutional trend during peak-flow periods. The NO 3 -N concentrations in water samples collected during the 2001 spring fertilizer applications tended to increase from early to late spring. All of the ?? 15 N values were low, which is indicative of either an inorganic source or soil organic matter. Storm discharge contained increased concentrations of total suspended solids; thus, storms are responsible for most of the sediment accumulation in the lake. E. coli levels in 24% of the samples analyzed contained a most probable number (MPN) greater than 235/100 mL, which is the maximum acceptable level set for recreational waters in Indiana. E. coli does appear to be a potential health risk, particularly at Rubble spring. The sources of E. coli found at this spring may include barnyard runoff from a horse barn or wastes from a wastewater treatment facility. The pesticides atrazine, metolachlor, acetochlor, and simazine were detected during the spring of 2001. Atrazine, metolachlor, acetochlor, and simazine are used to suppress weeds during corn and soybean production. Additional sources of atrazine and simazine may result from application to right-of-ways, orchards, and managed forest areas. ?? 2006 Geological Society of America.

Special Paper of the Geological Society of America

Contaminant transport and accumulation in Massachusetts Bay and Boston Harbor: A summary of U.S. Geological Survey studies

The U.S. Geological Survey (USGS) is conducting studies in Boston Harbor, Massachusetts Bay, and Cape Cod Bay designed to define the geologic framework of the region and to understand the transport and accumulation of contaminated sediments. The region is being studied because of environmental problems caused by the introduction of wastes for a long time, because a new ocean outfall (to begin operation in 1995) will change the location for disposal of treated Boston sewage from Boston Harbor into Massachusetts Bay, and because of the need to understand the transport of sediments and associated contaminants in order to address a wide range of management questions. The USGS effort complements and is closely coordinated with the research and monitoring studies supported by the Massachusetts Environmental Trust, the Massachusetts Bays Program, and by the Massachusetts Water Resources Authority. The USGS study includes (1) geologic mapping, (2) circulation studies, (3) long-term current and sediment transport observations, (4) measurements of contaminant inventories and rates of sediment mixing and accumulation, (5) circulation modeling, (6) development of a contaminated sediments data base, and (7) information exchange. A long-term objective of the program is to develop a predictive capability for sediment transport and accumulation.

Massachusetts

Tools for groundwater protection planning: An example from McHenry County, Illinois, USA

This paper presents an approach for producing aquifer sensitivity maps from three-dimensional geologic maps, called stack-unit maps. Stack-unit maps depict the succession of geologic materials to a given depth, and aquifer sensitivity maps interpret the successions according to their ability to transmit potential contaminants. Using McHenry County, Illinois, as a case study, stack-unit maps and an aquifer sensitivity assessment were made to help land-use planners, public health officials, consultants, developers, and the public make informed decisions regarding land use. A map of aquifer sensitivity is important for planning because the county is one of the fastest growing counties in the nation, and highly vulnerable sand and gravel aquifers occur within 6 m of ground surface over 75% of its area. The aquifer sensitivity map can provide guidance to regulators seeking optimal protection of groundwater resources where these resources are particularly vulnerable. In addition, the map can be used to help officials direct waste-disposal and industrial facilities and other sensitive land-use practices to areas where the least damage is likely to occur, thereby reducing potential future liabilities.

Environmental Management

Intersection of wildfire and legacy mining poses risk to water quality

Mining and wildfires are both landscape disturbances that pose elevated and substantial hazards to water supplies and ecosystems due to increased erosion and transport of sediment, metals, and debris to downstream waters. The risk to water supplies may be amplified when these disturbances occur in the same watershed. This work describes mechanisms by which the intersection of mining and wildfire may lead to elevated metal concentrations in downstream waters: (1) conveyance of metal-rich ash and soil to surface waters, (2) increased dissolution and transport of dissolved metals due to direct contact of precipitation with mine waste, (3) increased erosion and transport of metal-rich sediment from mining waste, (4) remobilization of previously deposited metal-contaminated floodplain sediment by higher postfire flood flows, and (5) increased metal transport from underground mine workings. Predicted increases in wildfire size, frequency, and burn severity, together with the ongoing need for metal resources, indicate that improved mapping, monitoring, modeling, and mitigation techniques are needed to manage the geochemical hazard of the intersection of wildfire and mining and implications for water availability.

Environmental Science and Technology

Cognitive and behavioral coping in response to wildlife disease: The case of hunters and chronic wasting disease

The transactional model of stress and coping (TMSC) provides a conceptual framework for understanding adaptations to stressors like chronic wasting disease (CWD). Understanding hunter response to stressors is important because decreased participation and satisfaction can affect individual well-being, cultural traditions, agency revenue, and local economies. Using TMSC, we explored how deer hunters coped with CWD. We also compared involvement, and impacts and emotions related to CWD, inside and outside a CWD management zone. Then we examined coping related to CWD presence, and if the disease affected human health. Most hunters would cope using product shift (i.e., eating meat after a negative test result) rather than displacement (i.e., hunting elsewhere) or dropout. Hunters who may be displaced reported lower involvement in deer hunting, and increased worry about CWD. Results suggest that CWD information and testing may increase hunter worry. Funding expanded testing without prompting displacement or dropout are important management considerations.

Minnesota

New perspectives on a 140-year legacy of mining and abandoned mine cleanup in the San Juan Mountains, Colorado

The Gold King mine water release that occurred on 5 August 2015 near the historical mining community of Silverton, Colorado, highlights the environmental legacy that abandoned mines have on the environment. During reclamation efforts, a breach of collapsed workings at the Gold King mine sent 3 million gallons of acidic and metal-rich mine water into the upper Animas River, a tributary to the Colorado River basin. The Gold King mine is located in the scenic, western San Juan Mountains, a region renowned for its volcano-tectonic and gold-silver-base metal mineralization history. Prior to mining, acidic drainage from hydrothermally altered areas was a major source of metals and acidity to streams, and it continues to be so. In addition to abandoned hard rock metal mines, uranium mine waste poses a long-term storage and immobilization challenge in this area. Uranium resources are mined in the Colorado Plateau, which borders the San Juan Mountains on the west. Uranium processing and repository sites along the Animas River near Durango, Colorado, are a prime example of how the legacy of mining must be managed for the health and well-being of future generations. The San Juan Mountains are part of a geoenvironmental nexus where geology, mining, agriculture, recreation, and community issues converge. This trip will explore the geology, mining, and mine cleanup history in which a community-driven, watershed-based stakeholder process is an integral part. Research tools and historical data useful for understanding complex watersheds impacted by natural sources of metals and acidity overprinted by mining will also be discussed.

Colorado

The water-energy nexus: An earth science perspective

Water availability and use are closely connected with energy development and use. Water cannot be delivered to homes, businesses, and industries without energy, and most forms of energy development require large amounts of water. The United States faces two significant and sometimes competing challenges: to provide sustainable supplies of freshwater for humans and ecosystems and to ensure adequate sources of energy for future generations. This report reviews the complex ways in which water and energy are interconnected and describes the earth science data collection and research that can help the Nation address these important challenges. The earth sciences have been a cornerstone in developing our current understanding of the water-energy nexus. A full understanding of the nexus, however, is limited by uncertainty in our knowledge of fundamental issues, such as the quantity of freshwater that is available, the amount of water that is used in energy development, the effects that emerging energy development technologies have on water quality and quantity, and the amount of energy required to treat and deliver freshwater. Enhanced data collection and research can improve our understanding of these important issues and thereby lay the groundwork for informed resource management. Relevant earth science issues analyzed and discussed herein include freshwater availability; water use; ecosystems health; assessment of saline water resources; assessment of fossil-fuel, uranium, and geothermal resources; subsurface injection of wastewater and carbon dioxide and related induced seismicity; climate change and its effect on water availability and energy production; byproducts and waste streams of energy development; emerging energy-development technologies; and energy for water treatment and delivery.

Circular

Spatiotemporal causal inference with mechanistic ecological models: Evaluating targeted culling on chronic wasting disease dynamics in cervids

Spatiotemporal causal inference methods are needed to detect the effect of interventions on indirectly measured epidemiological outcomes that go beyond studying spatiotemporal correlations. Chronic wasting disease (CWD) causes neurological degeneration and eventual death to white-tailed deer ( Odocoileus virginianus ) in Wisconsin. Targeted culling involves removing deer after traditional hunting seasons in areas with high CWD prevalence. The evaluation of the causal effects of targeted culling in the spread and growth of CWD is an important unresolved research and CWD management question that can guide surveillance efforts. Reaction–diffusion partial differential equations (PDEs) can be used to mechanistically model the underlying spatiotemporal dynamics of wildlife diseases, like CWD, allowing researchers to make inference about unobserved epidemiological quantities. These models indirectly regress spatiotemporal covariates on diffusion and growth rates parameterizing such PDEs, obtaining associational conclusions. In this work we develop an innovative method to obtain causal estimators for the effect of targeted culling interventions on CWD epidemiological processes using an inverse-probability-of-treatment-weighted technique by means of marginal structural models embedded in the PDE fitting process. Additionally we establish a novel scheme for sensitivity analysis under unmeasured confounder for testing the hypothesis of a significant causal effect in the indirectly measured epidemiological outcomes. Our methods can be broadly used to study the impact of spatiotemporal interventions and treatment exposures in the epidemiological evolution of infectious diseases that can help to inform future efforts to mitigate public health implications and wildlife disease burden.

Wisconsin

Surveillance and monitoring of white-tailed deer for chronic wasting disease in the northeastern United States

Chronic wasting disease (CWD) is a prion disease that affects both wild and captive cervid populations. In the past 45 y, CWD has spread from northern Colorado to all bordering states, as well as the midwestern United States (Midwest) and northeastern United States (Northeast), Canada, and South Korea. Because CWD is a relatively new issue for wildlife management agencies in the Northeast, we surveyed a representative (e.g., cervid biologist, wildlife veterinarian) from 14 states to gain a better understanding of state-specific surveillance measures. Between 2002 and 2012, New York (37,093) and Pennsylvania (35,324) tested the greatest number of harvested white-tailed deer Odocoileus virginianus in the Northeast. Additionally, the 14 states surveyed have tested 121,730 harvested deer, or approximately 15,216/y, since CWD was first detected in 2005. The most common tissues used by agencies in the Northeast for testing were retropharyngeal lymph nodes, which have been determined to be the most reliable in detecting CWD in cervids. Understanding CWD surveillance efforts at a regional scale can help to provide guidance for the development of new surveillance plans or the improvement of existing ones. Furthermore, collaborations among state and regional agencies in the Northeast may attempt to identify deficiencies in surveillance by state or subregion.

Connecticut, Delaware, Maine, Maryland, Massachuse

Bioassessment of Hollis Creek, Oktibbeha County, Mississippi

Physical, chemical and biological components at five stations on Hollis Creek, Oktibbeha County, Mississippi were evaluated using Rapid Bioassessment Protocols (RBP) and the Sediment Quality Triad (SQT) on August 24-26, 1999, in order to assess potential biological impacts from the Starkville Waste Water Treatment Facility (WWTF) on downstream resources. Two stations were selected above the WWTF and three below. The WWTF discharges treated effluent into Hollis Creek, but during storm events raw sewage may be released. Hollis Creek is a tributary of the Noxubee River that traverses the northern portion of Noxubee National Wildlife Refuge, which is managed as bottomland hardwood forest land for the protection of fish and wildlife resources. Hollis Creek was channelized throughout most of its length, resulting in high, unstable banks, degraded stream channel and unstable substratum. The RBP scores for the habitat evaluations from each station indicated that Stations 1 and 2 had degraded habitat compared to the reference site, Station 5. Benthic macroinvertebrate and fish assemblages also indicated that the biological integrity at Stations 1 and 2 was less than that of the downstream stations. The SQT showed that Stations 1 and 2 were degraded and the most likely causes of the impairment were the elevated concentrations of polycylclic aromatic hydrocarbons and metals in the sediments; Hyalella azteca survival in pore water and growth in solid-phase sediment exposures were reduced at these upstream sites. The source of contaminants to the upper reaches appears to be storm-water runoff. The close concordance between the RBP and SQT in identifying site degradation provided a preponderance of evidence indicating that the upper reaches (Stations 1 and 2) of Hollis Creek were impacted. Biological conditions improved downstream of the WWTF, even though physical degradation steinming from channelization activities were still evident. The increased discharge and stabilized base flow provided by the WWTF appeared to benefit the physically-altered stream system. Impairment attributable to releases from the WWTF on downstream biological resources was not evident from this evaluation, and the potential for degradation in the Noxubee River and National Wildlife Refuge appears minimal.

Book

Large-scale assessment of genetic structure to assess risk of populations of a large herbivore to disease

Chronic wasting disease (CWD) can spread among cervids by direct and indirect transmission, the former being more likely in emerging areas. Identifying subpopulations allows the delineation of focal areas to target for intervention. We aimed to assess the population structure of white-tailed deer ( Odocoileus virginianus ) in the northeastern United States at a regional scale to inform managers regarding gene flow throughout the region. We genotyped 10 microsatellites in 5701 wild deer samples from Maryland, New York, Ohio, Pennsylvania, and Virginia. We evaluated the distribution of genetic variability through spatial principal component analysis and inferred genetic structure using non-spatial and spatial Bayesian clustering algorithms (BCAs). We simulated populations representing each inferred wild cluster, wild deer in each state and each physiographic province, total wild population, and a captive population. We conducted genetic assignment tests using these potential sources, calculating the probability of samples being correctly assigned to their origin. Non-spatial BCA identified two clusters across the region, while spatial BCA suggested a maximum of nine clusters. Assignment tests correctly placed deer into captive or wild origin in most cases (94%), as previously reported, but performance varied when assigning wild deer to more specific origins. Assignments to clusters inferred via non-spatial BCA performed well, but efficiency was greatly reduced when assigning samples to clusters inferred via spatial BCA. Differences between spatial BCA clusters are not strong enough to make assignment tests a reliable method for inferring the geographic origin of deer using 10 microsatellites. However, the genetic distinction between clusters may indicate natural and anthropogenic barriers of interest for management.

Maryland, New York, Ohio, Pennsylvania, West Virgi

Environmental framework of ground‐water contamination

Ramifications of contamination are increasingly involved in the majority of ground‐water problems. The volume of usable ground water is shrinking in many places because of dispersion of contaminated water . Consideration of ground‐water contamination as a multitude of independent problems, separately solvable as each problem arises, is outmoded; wise policies, relating water supply to contamination potential, are needed to alleviate and to forestall problems. Methodology of managing contamination problems calls for appropriate classification of the hydrogeologic environment; these classifications include aspects of interdependent factors such as permeability, sorption, hydraulic gradient, position of water table relative to some base, and distance from source of contamination . Effective evaluations relate the dynamics of the hydrogeologic environment to contingencies involving contamination , as man changes his water ‐development and waste‐disposal practices. Ways of contamination and pertinent parts of the physical environment include: waste‐disposal practices (at or near land surface and in deep formations), artificial recharge (at land surface and in aquifers), accidents, and salt‐ water contamination of aquifers (shallow depth from salty surface water and at variable depths from subjacent salty aquifers). Evaluation of waste‐disposal problems calls for appreciation of two opposing tendencies–the tendency of wastes to move with ground water and the tendency to be attenuated near disposal sites by decay or inherent decrease in potency, by chemical and physical sorption, and by dilution through dispersion of ground water . Mixed wastes of differing attenuation habits represent special complex problems.

Groundwater