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USGS2011

Late Pleistocene dune activity in the central Great Plains, USA

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of cold, short growing seasons with relatively low precipitation and low atmospheric CO2 that increased plant moisture stress, limiting the ability of vegetation to stabilize active dune sand. The apparent coexistence of large mobile dunes with boreal forest taxa suggests a Late Pleistocene environment with few modern analogs. ?? 2011 Elsevier Ltd.

Quaternary Science Reviews↗

USGS1976

Geology and hydrology of radioactive solid-waste burial grounds at the Hanford Reservation, Washington

The geology and hydrology of radioactive solid waste burial grounds at the Hanford Reservation were investigated, using existing data, by the U.S. Geological Survey as part of the waste management plan of the Richland Operations Office of the Energy Research and Development Administration. The purpose of the investigation was to assist the operations office in characterizing the burial sites as to present environmental safety and as to their suitability for long-term storage (several thousand to tens of thousands of years) of radioactive sol id wastes. The burial ground sites fall into two classifications: (1) those on the low stream terraces adjacent to the Columbia River, mainly in the 100 Areas and 300 Area, and (2) those lying on the high terraces south of Gable Mountain in the 200 Areas. Evaluation of the suitability of the burial grounds for long-term storage was made almost entirely on hydrologic, geologic, and topographic criteria. Of greatest concern was the possibility that radionuclides might be leached from the buried wastes by infiltrating water and carried downward to the water table. The climate is semi-arid and the average annual precipitation is 6.4 inches at the Hanford Meteorological Station. However, the precipitation is seasonally distributed with about 50 percent occurring during the months of November, December, January, and February when evapotranspiration is negligible and conditions for infiltration are most favorable. None of the burial grounds are instrumented with monitoring devices that could be used to determine if radionuclides derived from them are reaching the water table. Burial grounds on the low stream terraces are mainly underlain by permeable materials and the water table lies at relatively shallow depths. Radionuclides conceivably could be leached from these burial grounds by percolating soil water, and radionuclides might reach the Columbia River in a relatively short time. These sites could also be inundated by erosion during a catastrophic flood. For these reasons, they are judged to be unsuited for long-term storage. Local conditions at several of these burial grounds are particularly unfavorable from the standpoint of safety. Depressions and swales at some burial grounds, such as numbers 4 and 5 in the 300 Area in which runoff can collect, enhance the possibility of water infiltrating through the buried wastes and transporting radionuclides to the water table. Also, during a high stage of the Columbia River, the water table conceivably could rise into burial grounds l and 2 of the 100 F Area. Most of the burial grounds on the low terraces contain either (1) reactor components and related equipment bearing activation products, principally cobalt-60, or (2) less hazardous radioactive materials such as uranium. The inventory of activation products in these burial grounds will decay to a safe level in a relatively short period of time (about 100 years), according to estimates made by C. D. Corbit, Douglas United Nuclear, Inc., 1969. The inventory of radionuclides is not considered by the ERDA staff to be complete, however. At these burial grounds containing activation products or less hazardous materials, investigations should be made of the radioactivity in soil and ground water beneath selected representative sites to verify that radionuclides are not migrating from the burial grounds. If migration is detected, field investigations should be made to determine the source or sources of the radionuclides and the desirability of removing the source wastes. Other burial grounds on the low terraces contain plutonium and fission products, which require long-term storage. Both the 300 WYE and the 300 North burial grounds are reported to contain plutonium in large quantities. Burial ground no. l in the 300 Area reportedly also contains plutonium. The inventory records of any other burial grounds on the low terraces suspected of containing plutonium should be reviewed to determine if pl

Open-File Report↗

USGS2001

Review and analysis of available streamflow and water-quality data for Park County, Colorado, 1962-98

Information on streamflow and surface-water and ground-water quality in Park County, Colorado, was compiled from several Federal, State, and local agencies. The data were reviewed and analyzed to provide a perspective of recent (1962-98) water-resource conditions and to help identify current and future water-quantity and water-quality concerns. Streamflow has been monitored at more than 40 sites in the county, and data for some sites date back to the early 1900's. Existing data indicate a need for increased archival of streamflow data for future use and analysis. In 1998, streamflow was continuously monitored at about 30 sites, but data were stored in a data base for only 10 sites. Water-quality data were compiled for 125 surface-water sites, 398 wells, and 30 springs. The amount of data varied considerably among sites; however, the available information provided a general indication of where water-quality constituent concentrations met or exceeded water-quality standards. Park County is primarily drained by streams in the South Platte River Basin and to a lesser extent by streams in the Arkansas River Basin. In the South Platte River Basin in Park County, more than one-half the annual streamflow occurs in May, June, and July in response to snowmelt in the mountainous headwaters. The annual snowpack is comparatively less in the Arkansas River Basin in Park County, and mean monthly streamflow is more consistent throughout the year. In some streams, the timing and magnitude of streamflow have been altered by main-stem reservoirs or by interbasin water transfers. Most values of surface-water temperature, dissolved oxygen, and pH were within recommended limits set by the Colorado Department of Public Health and Environment. Specific conductance (an indirect measure of the dissolved-solids concentration) generally was lowest in streams of the upper South Platte River Basin and higher in the southern one-half of the county in the Arkansas River Basin and in the South Platte River downstream from Antero Reservoir. Historical nitrogen concentrations in surface water were small. Nitrite was not detected, most un-ionized ammonia concentrations were less than 0.02 milligram per liter, and all nitrate concentrations were less than 1.2 milligrams per liter. Nitrate concentrations were higher in urban and built-up areas than in rangeland and forest areas. Most median concentrations of total phosphorus at individual sites were less than 0.05 milligram per liter, and concentrations were not significantly different among urban and built-up, rangeland, and forest areas. An upward trend in total phosphorus concentration was determined for flow from the East Portal of the Harold D. Roberts Tunnel, but the slope of the trend line was small and the concentrations were equal or nearly equal to the detection limit of 0.01 milligram per liter. Using median phosphorus loads for two South Platte River sites, the annual phosphorus load transported out of Park County in the South Platte River was calculated to be about 10,000 pounds. Median iron and manganese concentrations for most areas of Park County were less than in-stream water-quality standards, even though several individual concentrations were one to two orders of magnitude larger than the standards. The largest concentrations of aluminum, cadmium, chromium, copper, iron, manganese, nickel, and zinc were from the upper North Fork South Platte River Basin or the Mosquito Creek Basin. All ground-water concentrations of chloride and most ground-water concentrations of sulfate were less than the U.S. Environmental Protection Agency (USEPA) drinking-water standard of 250 milligrams per liter. Median dissolved-solids concentrations in ground water ranged from 160 milligrams per liter in the crystalline-rock aquifers to 257 milligrams per liter in the sedimentary-rock aquifers. Dissolved-solids concentrations greater than the USEPA drinking-water standard of 500 milligrams per liter were detected in abo

Water-Resources Investigations Report↗

USGS2017

U.S. Geological Survey Karst Interest Group Proceedings, San Antonio, Texas, May 16–18, 2017

Introduction and Acknowledgments Karst aquifer systems are present throughout parts of the United States and some of its territories, and have developed in carbonate rocks (primarily limestone and dolomite) and evaporites (gypsum, anhydrite, and halite) that span an interval of time encompassing more than 550 million years. The depositional environments, diagenetic processes, post-depositional tectonic events, and geochemical weathering processes that form karst aquifers are varied and complex. These factors involve biological, chemical, and physical changes that when combined with the diverse climatic regimes in which karst development has taken place, result in the unique dual- or triple-porosity nature of karst aquifers. These complex hydrogeologic systems typically represent challenging and unique conditions to scientists attempting to study groundwater flow and contaminant transport in these terrains. The dissolution of carbonate rocks and the subsequent development of distinct and beautiful landscapes, caverns, and springs have resulted in the most exceptional karst areas being designated as national or state parks. Tens of thousands of similar areas in the United States have been developed into commercial caverns and known privately owned caves. Both public and private properties provide access for scientists to study the flow of groundwater in situ . Likewise, the range and complexity of landforms and groundwater flow systems associated with karst terrains are enormous, perhaps more than for any other aquifer type. Karst aquifers and landscapes that form in tropical areas, such as the cockpit karst along the north coast of Puerto Rico, differ greatly from karst landforms in more arid climates, such as the Edwards Plateau in west-central Texas or the Guadalupe Mountains near Carlsbad, New Mexico, where hypogenic processes have played a major role in speleogenesis. Many of these public and private lands also contain unique flora and fauna associated with these karst hydrogeologic systems. As a result, numerous federal, state, and local agencies have a strong interest in the study of karst terrains. Many of the major springs and aquifers in the United States have developed in carbonate rocks, such as the Floridan aquifer system in Florida and parts of Alabama, Georgia, and South Carolina; the Ozark Plateaus aquifer system in parts of Arkansas, Kansas, Missouri, and Oklahoma; and the Edwards-Trinity aquifer system in west-central Texas. These aquifers, and the springs that discharge from them, serve as major water-supply sources and form unique ecological habitats. Competition for the water resources of karst aquifers is common, and urban development and the lack of attenuation of contaminants in karst areas due to dissolution features that form direct pathways into karst aquifers can impact the ecosystem and water quality associated with these aquifers. The concept for developing a platform for interaction among scientists within the U.S. Geological Survey (USGS) working on karst-related studies evolved from the November 1999 National Groundwater Meeting of the USGS. As a result, the Karst Interest Group (KIG) was formed in 2000. The KIG is a loose-knit, grass-roots organization of USGS and non-USGS scientists and researchers devoted to fostering better communication among scientists working on, or interested in, karst science. The primary mission of the KIG is to encourage and support interdisciplinary collaboration and technology transfer among scientists working in karst areas. Additionally, the KIG encourages collaborative studies between the different mission areas of the USGS as well as with other federal and state agencies, and with researchers from academia and institutes. To accomplish its mission, the KIG has organized a series of workshops that have been held near nationally important karst areas. To date (2017) seven KIG workshops, including the workshop documented in this report, have been held. The workshops typically include oral and poster sessions on selected karst-related topics and research, as well as field trips to local karst areas. To increase non-USGS participation an effort was made for the workshops to be held at a university or institute beginning with the fourth workshop. Proceedings of the workshops are published by the USGS and are available online at the USGS publications warehouse https://pubs.er.usgs.gov/ by using the search term “karst interest group.” The first KIG workshop was held in St. Petersburg, Florida, in 2001, in the vicinity of the large springs and other karst features of the Floridan aquifer system. The second KIG workshop was held in 2002, in Shepherdstown, West Virginia, in proximity to the carbonate aquifers of the northern Shenandoah Valley, and highlighted an invited presentation on karst literature by the late Barry F. Beck of P.E. LaMoreaux and Associates. The third KIG workshop was held in 2005, in Rapid City, South Dakota, near evaporite karst features in limestones of the Madison Group in the Black Hills of South Dakota. The Rapid City KIG workshop included field trips to Wind Cave National Park and Jewel Cave National Monument, and featured a presentation by Thomas Casadevall, then USGS Central Region Director, on the status of Earth science at the USGS. The fourth KIG workshop in 2008 was hosted by the Hoffman Environmental Research Institute and Center for Cave and Karst Studies at Western Kentucky University in Bowling Green, Kentucky, near Mammoth Cave National Park and karst features of the Chester Upland and Pennyroyal Plateau. The workshop featured a late-night field trip into Mammoth Cave led by Rickard Toomey and Rick Olsen, National Park Service. The fifth KIG workshop in 2011 was a joint meeting of the USGS KIG and University of Arkansas HydroDays, hosted by the Department of Geosciences at the University of Arkansas in Fayetteville. The workshop featured an outstanding field trip to the unique karst terrain along the Buffalo National River in the southern Ozarks, and a keynote presentation on paleokarst in the United States was delivered by Art and Peggy Palmer. The sixth KIG workshop was hosted by the National Cave and Karst Research Institute (NCKRI) in 2014, in Carlsbad, New Mexico. George Veni, Director of the NCKRI, served as a co-chair of the workshop with Eve Kuniansky of the USGS. The workshop featured speaker Dr. Penelope Boston, Director of Cave and Karst Studies at New Mexico Tech, Socorro, and Academic Director at the NCKRI, who addressed the future of karst research. The field trip on evaporite karst of the lower Pecos Valley was led by Lewis Land (NCKRI karst hydrologist), and the field trip on the geology of Carlsbad Caverns National Park was led by George Veni. This current seventh KIG workshop is being held in San Antonio at the University of Texas at San Antonio (UTSA). This 2017 workshop is being hosted by the Department of Geological Sciences’ Student Geological Society (SGS), and student chapters of the American Association of Petroleum Geologists (AAPG) and Association of Engineering Geologists (AEG), with support by the UTSA Department of Geological Sciences and Center for Water Research. The UTSA student chapter presidents, Jose Silvestre (SGS), John Cooper (AAPG), and Tyler Mead (AEG) serve as co-chairs of the 2017 workshop with Eve Kuniansky of the USGS. The technical session committee is chaired by Eve Kuniansky, USGS, and includes Michael Bradley, Tom Byl, Rebecca Lambert, John Lane, and James Kaufmann, all USGS, and Patrick Tucci, retired USGS. The logistics committee includes Amy Clark, Yongli Gao, and Lance Lambert (Department Chair), UTSA Department of Geological Sciences; and Ryan Banta and Allan Clark, USGS, San Antonio, Texas. The field trip committee is chaired by Allan Clark and includes Amy Clark, Yongli Gao, and Keith Muehlestein, UTSA; Marcus Gary, Edwards Aquifer Authority and University of Texas at Austin; Ron Green, Southwest Research Institute; Geary Schindel, Edwards Aquifer Authority; and George Veni, NCKRI. Additionally, two organizations have assisted the UTSA student chapters in hosting the meeting by donating funds to the chapters: the Edwards Aquifer Authority, San Antonio, Texas, and the Barton Springs Edwards Aquifer Authority, Austin, Texas. Additionally, Yongli Gao, Center for Water Research and Department of Geological Sciences, UTSA, helped develop sessions on cave and karst research in China for this workshop. These proceedings could not have been accomplished without the assistance of Lawrence E. Spangler as co-editor who not only has subject matter expertise, but also serves as an editor with the USGS Science Publishing Network. We sincerely hope that this workshop continues to promote future collaboration among scientists of varied and diverse backgrounds, and improves our understanding of karst aquifer systems in the United States and its territories. The extended abstracts of USGS authors were peer reviewed and approved for publication by the USGS. Articles submitted by university researchers and other federal and state agencies did not go through the formal USGS peer review and approval process, and therefore may not adhere to USGS editorial standards or stratigraphic nomenclature. However, all articles had a minimum of two peer reviews and were edited for consistency of appearance in the proceedings. The use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The USGS Water Availability and Use Science Program funded the publication costs of the proceedings.

Scientific Investigations Report↗

USGS2010

Legacy of the California Gold Rush: Environmental geochemistry of arsenic in the southern Mother Lode Gold District

Gold mining activity in the Sierra Nevada foothills, both recently and during the California Gold Rush, has exposed arsenic-rich pyritic rocks to weathering and erosion. This study describes arsenic concentration and speciation in three hydrogeologic settings in the southern Mother Lode Gold District: mineralized outcrops and mine waste rock (overburden); mill tailings submerged in a water reservoir; and lake waters in this monomictic reservoir and in a monomictic lake developing within a recent open-pit mine. These environments are characterized by distinct modes of rock-water interaction that influence the local transport and fate of arsenic. Arsenic in outcrops and waste rock occurs in arsenian pyrite containing an average of 2 wt% arsenic. Arsenic is concentrated up to 1300 ppm in fine-grained, friable, iron-rich weathering products of the arsenian pyrite (goethite, jarosite, copiapite), which develop as efflorescences and crusts on weathering outcrops. Arsenic is sorbed as a bidentate complex on goethite, and substitutes for sulfate in jarosite. Submerged mill tailings obtained by gravity core at Don Pedro Reservoir contain arsenic up to 300 ppm in coarse sand layers. Overlying surface muds have less arsenic in the solid fraction but higher concentrations in porewaters (up to 500 μg/L) than the sands. Fine quartz tailings also contain up to 3.5 ppm mercury related to the ore processing. The pH values in sediment porewaters range from 3.7 in buried gypsum-bearing sands and tailings to 7 in the overlying lake sediments. Reservoir waters immediately above the cores contain up to 3.5 μg/L arsenic; lake waters away from the submerged tailings typically contain less than 1 μg/L arsenic. Dewatering during excavation of the Harvard open-pit mine produced a hydrologic cone of depression that has been recovering toward the pre-mining groundwater configuration since mining ended in 1994. Aqueous arsenic concentrations in the 80 m deep pit lake are up to 1000 μg/L. Redistribution of the arsenic occurs during summer stratification, with highest concentrations at middle depths. The total mass of arsenic in the pit lake increases coinciding with early winter rains that erode, partially dissolve, and transport arsenic-bearing salts into the pit lake. Arsenic concentration, speciation, and distribution in the Sierra Nevada foothills depend on many factors, including the lithologic sources of arsenic, climatic influences on weathering of host minerals, and geochemical characteristics of waters with which source and secondary minerals react. Oxidation of arsenian pyrite to goethite, jarosite, and copiapite causes temporary attenuation of arsenic during summer, when these secondary minerals accumulate; subsequent rapid dissemination of arsenic into the aqueous environment is caused by annual winter storms. As the population of the Mother Lode area grows, it is increasingly important to consider these effects during planning and development of land and groundwater resources.

California↗

USGS2020

Holocene paleoclimate change in the western US: The importance of chronology in discerning patterns and drivers

Sediment in lakes and meadows forms a powerful archive that can be used to reconstruct environmental change through time. Reconstructions of lake level, of chemical, biological, and hydrological conditions, and of surrounding vegetation provide detailed information about past climate conditions, both locally and regionally. Indeed, most of our current knowledge of centennial- to millennial-scale climate variability in the arid western United States, where information about past hydroclimate is particularly important, comes from such sediment-based reconstructions. The pressing need for robust, precise predictions of future conditions is a significant motivation for paleoclimate science, and current research questions frequently require Holocene reconstructions to be resolved at sub-centennial timescales. Increasingly, regional syntheses seek to identify synoptic-scale patterns similar to those defined from modern observations (seasonal, interannual, multi-decadal, etc.) or to compare with the output of climate model simulations. However, the age control on existing records, especially those more than about 20 years old, is often sufficient only for millennial-scale interpretation. Here we assess the age control for 84 published and unpublished records from lakes and meadows in the Great Basin, California, and desert southwest, and use Bayesian modeling to evaluate the 95% uncertainty ranges for the 42 best-dated records. In the Late Holocene, about half of the 42 records have <400-year mean uncertainty ranges; however, high-precision age control is especially critical for young records, used to develop an accurate understanding of a proxy’s response to known climate variations. In the Middle Holocene, records vary from 400 to >800-year mean uncertainty and records of the Early Holocene have 600- to >1400-year mean uncertainty ranges. We find that the largest control on modeled uncertainties is dating density, with at least 2 dates/kyr being optimal and suggest obtaining “range-finder” dates at the onset of a study to better predict the total number of dates needed for an adequate age model. Such a density avoids a commonly observed phenomenon of significant peaks in uncertainty arising in gaps between age control points. Analysis of the uncertainties associated with proxy shifts reveal that more than half are >400 years. Although such large uncertainties currently prevent sub-centennial interpretations in most cases, increased dating density, strategic use of limited funds (including budgeting for a 2 date/kyr minimum at the proposal stage), construction of age-depth models with Bayesian methods, and critical evaluation of chronological uncertainty will shed light on past climate variability at finer timescales, enhancing our understanding of global and regional drivers of western U.S. climate.

California, Idaho, Nevada, Oregon, Utah↗

USGS2007

Scale-dependent approaches to modeling spatial epidemiology of chronic wasting disease.

This e-book is the product of a second workshop that was funded and promoted by the United States Geological Survey to enhance cooperation between states for the management of chronic wasting disease (CWD). The first workshop addressed issues surrounding the statistical design and collection of surveillance data for CWD. The second workshop, from which this document arose, followed logically from the first workshop and focused on appropriate methods for analysis, interpretation, and use of CWD surveillance and related epidemiology data. Consequently, the emphasis of this e-book is on modeling approaches to describe and gain insight of the spatial epidemiology of CWD. We designed this e-book for wildlife managers and biologists who are responsible for the surveillance of CWD in their state or agency. We chose spatial methods that are popular or common in the spatial epidemiology literature and evaluated them for their relevance to modeling CWD. Our opinion of the usefulness and relevance of each method was based on the type of field data commonly collected as part of CWD surveillance programs and what we know about CWD biology, ecology, and epidemiology. Specifically, we expected the field data to consist primarily of the infection status of a harvested or culled sample along with its date of collection (not date of infection), location, and demographic status. We evaluated methods in light of the fact that CWD does not appear to spread rapidly through wild populations, relative to more highly contagious viruses, and can be spread directly from animal to animal or indirectly through environmental contamination. We discovered that many of the wellpublished methods were developed for fast-spreading human diseases, such as influenza and measles. While these methods are applicable to fast spreading wildlife diseases, such as foot-and-mouth disease or West Nile virus, many are not likely to work well for CWD. Only limited data exist to evaluate geographic and spatial spread because many locations where we find CWD tend to be locations where samples have just been taken or sample sizes have just become large enough to have a high probability of detecting a low prevalence. Consequently, methods that work well to describe or predict the spread of foot-and-mouth disease throughout England, which occurred within a year, do not work well for describing or predicting CWD spread. We did not exclude methods that we regarded as inappropriate; rather, we included methods that are commonly used for disease epidemiology and then discussed their applicability for modeling the spatial epidemiology of CWD. We hope including inappropriate methods with an explanation of why they are ill-suited for CWD will make it easier to drop them from consideration and explain to others why they were not recommended for spatial modeling of CWD. We organized the three chapters by scale and extent for which each method was developed or best suited. The first chapter covers methods appropriate to multi-jurisdictional or multi-state modeling, which we call “regional” scale. The second chapter covers methods appropriate for within state areas such as wildlife management units or metapopulations, which we call “landscape” scale. The third chapter covers methods appropriate for population or individual-based modeling, which we call “fine” scale. We know this rubric is somewhat artificial because many methods work at multiple scales. We hope, however, that this structure addresses some of the challenges faced by managers that work at local, regional, state, and national scales. Further, the resolution of empirical data often changes with spatial scale, which affects the utility of different modeling approaches. For example, individual-based models work best at modeling spread within populations, while risk analysis is most useful for summarizing data over larger scales such as a region. Because some methods are applicable at several scales, however, we included a graphic at the beginning of each method that indicates the range of scales for which it applies. For example, the graphic to the right indicates that the method is most applicable for regional-scale modeling. There is also a question of resolution as well as scale and extent for each method. CWD surveillance data have been collected over large areas, such as a wildlife management unit or state, but the resolution of the data may be fine scale with GPS locations for many samples. For each method, we described the required resolution of the data and describe the type of data required, as well as what questions the method could answer and how useful the method is, given typical CWD data. For each scale, we presented a focal approach that would be useful for understanding the spatial pattern and epidemiology of CWD, as well as being a useful tool for CWD management. The focal approaches include risk analysis and micromaps for the regional scale, cluster analysis for the landscape scale, and individual based modeling for the fine scale of within population. For each of these methods, we used simulated data and walked through the method step by step to fully illustrate the “how to”, with specifics about what is input and output, as well as what questions the method addresses. We also provided a summary table to, at a glance, describe the scale, questions that can be addressed, and general data required for each method described in this e-book. We hope that this review will be helpful to biologists and managers by increasing the utility of their surveillance data, and ultimately be useful for increasing our understanding of CWD and allowing wildlife biologists and managers to move beyond retroactive fire-fighting to proactive preventative action.

Book↗

USGS2016

Hydrologic analyses in support of the Navajo Generating Station–Kayenta Mine Complex environmental impact statement

Introduction The U.S. Department of Interior’s Bureau of Reclamation, Lower Colorado Region (Reclamation) is preparing an environmental impact statement (EIS) for the Navajo Generating Station-Kayenta Mine Complex Project (NGS-KMC Project). The proposed project involves various Federal approvals that would facilitate continued operation of the Navajo Generating Station (NGS) from December 23, 2019 through 2044, and continued operation of the Kayenta Mine and support facilities (collectively called the Kayenta Mine Complex, or KMC) to supply coal to the NGS for this operational period. The EIS will consider several project alternatives that are likely to produce different effects on the Navajo (N) aquifer; the N aquifer is the principal water resource in the Black Mesa area used by the Navajo Nation, Hopi Tribe, and Peabody Western Coal Company (PWCC). The N aquifer is composed of three hydraulically connected formations—the Navajo Sandstone, the Kayenta Formation, and the Lukachukai Member of the Wingate Sandstone—that function as a single aquifer. The N aquifer is confined under most of Black Mesa, and the overlying stratigraphy limits recharge to this part of the aquifer. The N aquifer is unconfined in areas surrounding Black Mesa, and most recharge occurs where the Navajo Sandstone is exposed in the area near Shonto, Arizona. Overlying the N aquifer is the D aquifer, which includes the Dakota Sandstone, Morrison Formation, Entrada Sandstone, and Carmel Formation. The aquifer is named for the Dakota Sandstone, which is the primary water-bearing unit. The NGS is located near Page, Arizona on the Navajo Nation. The KMC, which delivers coal to NGS by way of a dedicated electric railroad, is located approximately 83 miles southeast of NGS (about 125 miles northeast of Flagstaff, Arizona). The Kayenta Mine permit area is located on about 44,073 acres of land leased within the boundaries of the Hopi and Navajo Indian Reservations. KMC has been conducting mining and reclamation operations within the Kayenta Mine permit boundary since 1973. The KMC part of the proposed project requires approval by the Office of Surface Mining (OSM) of a significant revision of the mine’s permit to operate in accordance with the Surface Mine Control and Reclamation Act (Public Law 95-87, 91 Stat. 445 [30 U.S.C. 1201 et seq. ]) . The revision will identify coal resource areas that may be used to continue extracting coal at the present rate of approximately 8.2 million tons per year. The Kayenta Mine Complex uses water pumped from the D and N aquifers beneath PWCC’s leasehold to support mining and reclamation activities. Prior to 2006, water from the PWCC well field also was used to transport coal by way of a coal-slurry pipeline to the now-closed Mohave Generating Station. Water usage at the leasehold was approximately 4,100 acre-feet per year (acre-ft/yr) during the period the pipeline was in use, and declined to an average 1,255 acre-ft/yr from 2006 to 2011. The Probable Hydrologic Consequences (PHC) section of the mining and reclamation permit must be modified to project the consequences of extended water use by the mine for the duration of the KMC part of the project, including a post-mining reclamation period. Since 1971, the U.S. Geological Survey (USGS) has conducted the Black Mesa Monitoring Program, which consists of monitoring water levels and water quality in the N aquifer, compiling information on water use by PWCC and tribal communities, maintaining several stream-gaging stations, measuring discharge at selected springs, conducting special studies, and reporting findings. These data are useful in evaluating the effects on the N aquifer from PWCC and community pumping, and the effects of variable precipitation. The EIS will assess the impacts of continued pumping on the N aquifer, including changes in storage, water quality, and effects on spring and baseflow discharge, by proposed mining through 2044, and during the reclamation process to 2057. Several groundwater models exist for the area and Reclamation concluded it would conduct a peer review of the groundwater flow model that will be used to assess the direct, reasonably foreseeable indirect, and cumulative effects of future groundwater withdrawals on the D and N aquifers in the Black Mesa area. Reclamation made this determination because of the level of controversy around the effects of continued water use and the comments received from the 2014 draft EIS scoping meetings. Reclamation requested assistance from the USGS in evaluating existing groundwater flow models of the Black Mesa Basin that can be used to predict the effects of different project alternatives on the D and N aquifers.

Arizona↗

USGS2016

Accuracy assessment/validation methodology and results of 2010–11 land-cover/land-use data for Pools 13, 26, La Grange, and Open River South, Upper Mississippi River System

Introduction/Background The U.S. Geological Survey (USGS)-Upper Midwest Environmental Sciences Center (UMESC) was responsible for development of several land cover/land use (LCU) systemic datasets of the Upper Mississippi River System (UMRS). These efforts (1989 and 2000) were funded by the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration Program (UMRR) Long Term Resource Monitoring (LTRM) element. Development of systemic datasets includes the acquisition, processing, and serving of high-resolution aerial photography and land cover/land use spatial datasets ( http://www.umesc.usgs.gov/data_library/land_cover_use/land_cover_use_data.html ). In 2008, the UMRR reached a collaborative agreement with the U.S. Fish and Wildlife Service-Region 3 to collect high-resolution digital imagery of the entire UMRS floodplain during 2010–11 for LTRM. The UMESC helped acquire, process, and serve this imagery, as well as produce and serve the 2010–11 LCU systemic dataset of the UMRS floodplain. Digital imagery for Pools 13, 26, La Grange, and Open River South was collected using an Applanix DSS 439 digital sensor system with a 40 millimeter lens and Color Infrared (CIR) filter. The imagery was collected at a resolution of 20 centimeters/pixel (8 inches/pixel) for Pool 13 and 40 centimeters/pixel (16 inches/pixel) for Pools 26, Open River South, and La Grange. All imagery was projected to Universal Transverse Mercator (UTM) Zone 15, North American Datum of 1983 (NAD 83). The General Wetland Vegetation Classification (GWVC) system used for mapping is hierarchical, and its 31 classes can be collapsed into broader categories using either a 15- or 7-class level. While the 1989 and 2000 LCU systemic datasets have not gone through a traditional thematic accuracy assessment (AA) in the past, nor have they undergone a validation analysis, the end products are of high quality. For each systemic dataset produced (1989, 2000, 2010–11), extensive field reconnaissance is performed before photointerpretation. The intent of this field reconnaissance is to learn, test, and verify image signatures as they relate to vegetation types. Questionable areas on the imagery are visited, and the plants or land features observed in the area are recorded for reference. This procedure verifies vegetation signatures on the imagery with those on the ground. In addition, once the photointerpretation is complete, the final LCU dataset undergoes extensive quality assurance/quality control to ensure the imagery is mapped correctly. Since the 2000 LCU systemic dataset was developed, there has been a growing interest in completing thematic AAs for the LTRM LCU spatial datasets. The objective of an AA is to measure the probability that a particular location has been assigned its correct vegetation class. An AA estimates thematic (map class) errors in the data, giving users information needed to determine data suitability for a particular application. At the same time, data producers are able to learn more about the nature of errors in the data. Thus, the two attributes of an AA are “producers’ accuracy,” which is the probability that an AA point has been mapped correctly (also referred to as an error of omission); and “users’ accuracy,” which is the probability that the map actually represents what was found on the ground (also referred to as error of commission). Producers’ and users’ accuracies can be obtained from the same set of data by using different analyses. Accuracy assessment is an extensive effort that requires seasonal field personnel and equipment, data entry, analyses, and post processing—tasks that are costly and time consuming. The geospatial team at the UMESC has suggested a validation process for understanding the accuracy of the spatial datasets, which will be tested on at least some areas of the UMRS. Validation is not a true verification of map-class type in the field; however, it can provide the user of the map with useful information that is similar to a field AA. Similar to an AA, validation involves generating random points based on the total area for each map class. However, instead of collecting field data, two or three individuals not involved with the photo-interpretative mapping separately review each of the points onscreen and record a best-fit vegetation type(s) for each site. Once the individual analyses are complete, results are joined together and a comparative analysis is performed. The objective of this initial analysis is to identify areas where the validation results were in agreement (matches) and areas where validation results were in disagreement (mismatches). The two or three individuals then perform an analysis, looking at each mismatched site, and agree upon a final validation class. (If two vegetation types at a specific site appear to be equally prevalent, the validation team is permitted to assign the site two best-fit vegetation types.) Following the validation team’s comparative analysis of vegetation assignments, the data are entered into a database and compared to the mappers’ vegetation assignments. Agreements and disagreements between the map and validation classes are identified, and a contingency table is produced. This document presents the AA processes/results for Pools 13 and La Grange, as well as the validation process/results for Pools 13 and 26 and Open River South.

Iowa, Illinois, Minnesota, Missouri, Wisconsin↗

USGS2009

Prevention, early detection and containment of invasive, nonnative plants in the Hawaiian Islands: current efforts and needs

Introduction: Invasive, non-native plants (or environmental weeds) have long been recognized as a major threat to the native biodiversity of oceanic islands (Cronk & Fuller, 1995; Denslow, 2003). Globally, several hundred non-native plant species have been reported to have major impacts on natural areas on oceanic islands (Kueffer et al ., 2009). In Hawaii, at least some 50 non-native plant species reach dominance in natural areas (Kueffer et al ., 2009) and many of them are known to impact ecosystem processes or biodiversity. One example is the invasive Australian tree fern ( Cyathea cooperi ), which has been shown to be very efficient at utilizing soil nitrogen and can grow six times as rapidly in height, maintain four times more fronds, and produce significantly more fertile fronds per month than the native Hawaiian endemic tree ferns, Cibotium spp. (Durand & Goldstein, 2001a, b). Additionally, while native tree ferns provide an ideal substrate for epiphytic growth of many understory ferns and flowering plants, the Australian tree fern has the effect of impoverishing the understory and failing to support an abundance of native epiphytes (Medeiros & Loope, 1993). Other notorious examples of invasive plant species problematic for biodiversity and ecosystem processes in Hawaii include miconia ( Miconia calvescens ), strawberry guava ( Psidium cattleianum ), albizia ( Falcataria moluccana ), firetree ( Morella faya ), clidemia ( Clidemia hirta ), kahili ginger ( Hedychium gardnerianum ), and fountain grass ( Pennisetum setaceum ), to name just a few. Fireweed ( Senecio madagascariensis ) is a recent example of a seriously problematic invasive species for Hawaii’s agriculture and is damaging certain high-elevations native ecosystems as well. The threat of invasive plants has long been recognized in Hawaii and is well documented (e.g. Cox, 1999; Loope & Kraus, 2009 in press; Loope et al ., 2004; Mooney & Drake, 1986; Stone & Scott, 1985; Stone et al. , 1992). In many respects, Hawaii may be near the forefront among national and international efforts to address the burgeoning threat of invasive plants, perhaps especially in the field of outreach and education (Holt, 1996; Van Driesche & Van Driesche, 2000). However, given the scale of the problem many challenges still need to be addressed and gaps in the existing management system need to be identified. In particular, it appears that new non-native plant species are still introduced to the Hawaiian Islands at a high rate with little or no regard for their potential invasiveness. In fact, a Pacific-wide and a global survey of non-native plants on oceanic islands have both shown that on Hawaii among all archipelagos by far the highest number of problematic invasive species known from other areas in the world is already present (Denslow et al . 2009, Kueffer et al . 2009). Hawaii lacks an effective mechanism for tracking what species are present or incoming. For instance, early detection nursery surveys conducted on Maui in 2008 found over 300 species of cultivated vascular plants that have not previously been recorded in Hawaii (Starr et al. , in prep.). In spite of an innovative Hawaii Biological Survey (e.g. Eldredge & Evenhuis, 2003), there is no mechanism for recording presence of a species until it becomes naturalized. Some of these new introductions may quickly become serious pests. Fireweed, first recorded in Hawaii on the Big Island in the early 1980s, is now considered one of the Kueffer & Loope 2009 5/48 worst weeds of pastures and is also invading natural areas from near sea level to above 10,000 feet. Although the cultivated and as yet non-invasive Cortaderia selloana has been present in Hawaii for 50 years or more, the morphologically similar Cortaderia jubata was simultaneously found to be present on Maui and invading on a large scale in 1989. It played an important role in inspiring the establishment of the Maui Invasive Species Committee (MISC) in 1997, and MISC now spends roughly $200,000 per year removing and containing C. jubata to keep it from becoming widespread in high elevation conservation lands of East and West Maui. The existence of many similar examples shows that to date regulatory action to prevent new invasive plant species from establishing and spreading in Hawaii has not yet been as successful as it needs to be. In particular, because some problematic invasive species known from other areas in the world (Kueffer et al ., 2009; Weber, 2003) have not yet been recorded from Hawaii, preventive measures against the introduction and spread of such likely invasive species is therefore an urgent need for Hawaii. Indeed, regulation of importation and early detection and eradication of introduced species before they become abundant and widespread are widely considered the most cost-efficient and often only effective measures against the threat of new invasive species (Kueffer & Hirsch Hadorn, 2008; Wittenberg & Cock, 2001). Timing seems favorable for Hawaii to achieve effective protection against the threat of new invasive species through prevention, early detection, and eradication/containment. Through the establishment and evolution of Invasive Species Committees (ISCs) on each major Hawaiian island, the institutional capacity has been built up for prevention, early detection, containment, and outreach at an island scale. Weed risk assessment (Daehler et al ., 2004) and early detection methodologies (Starr et al. , in review-a, b) have been developed and tested specifically for Hawaii. Containment strategies have been successful (e.g., Special Ecological Areas in Hawaii Volcanoes National Park), and so have eradications of particular species on an island scale (e.g. mullein ( Verbascum thapsus ) and other species on Maui, fireweed ( Senecio madagascariensis ) on Kauai). These successful management strategies may be further strengthened through recently developed novel approaches in research (e.g. remote sensing, species distribution modelling, and molecular genetics tools). Another major recent achievement is the gained support of the plant industry for preventive measures against invasive species (see p. 13ff). Last but not least, regulatory action is also moving forward. Passage of House Bill 2517 by the 2008 Hawaii House and Senate and prompt signing of the bill into law by the Governor provides hope that action to ban the sale of a meaningful suite of restricted weeds can quickly proceed through the rulemaking phase into the implementation phase. This report documents these achievements and experiences and provides a range of perspectives on how to further develop prevention, early detection and containment of invasive species in Hawaii. The report is based on a symposium and workshop held at the 2008 Hawaii Conservation Conference in Honolulu on 31 July 2008.

Hawaii↗

USGS2003

Kelp forest ecosystems: Biodiversity, stability, resilience and future

Kelp forests are phyletically diverse, structurally complex and highly productive components of coldwater rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40–60° latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2–3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The large-scale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

Environmental Conservation↗

USGS2000

Seasonal distribution of bird populations at the Patuxent Research Refuge

A detailed study of seasonal changes in bird populationswas made at the Patuxent Research Refuge, located between Bowie and Laurel, Maryland during the years 1936-1949. The history of the Refuge is reviewed and its physical and biological characteristlcs summarized.. The methods of study used during the investigation mcluded: periodic censuses of a representative 304-acre study area over a two-year period; a census of the breeding population of the entire. Refuge during one year; detailed population studies of representative habitats during the breeding season; censuses of the wintering population of. the entire Refuge during two years; general surveys of wintering populations for seven years; and general observations of seasonal changes in bird populatlons over a fourteen-year period, including data from an extensive banding program and from many special types of censuses. The phenology of the Refuge is described in conslderable detail throughout the year, with special attention given to major fluctuatIons in bIrd populations as correlated with climatic changes and with seasonal aspectlon. of the vegetation. The component specIes of birds m the more important migration waves are listed. Figures approximating the Refuge breeding and wmtering populations are given, while indices representing the relative abundance of bird populations, based on figures from the two-year seasonal populatlon study, were obtained for the entire year. The greatest variety of species as well as the greatest number of individuals occurred on the Refuge during the migration .periods in spring and fall, the variety of species being slightly higher in spring than in fa!l, while the population of individuals was considerably higher in fall. Wmtering and breeding populations were low and relatively stable compared to the populations at other seasons.The ecological affinities of the bird populations differed greatly from one season to another. Species characteristic of edge habitats were much more numerous in winter, while forest species were predominant in summer. Insectivorous species comprised a large proportion (40 to 60 percent) of the total population during the warmer months, but were of minor importance in winter. The greatest number of species of birds on the Refuge occurred during the population peaks of insectivorous species, while the largest number of individuals was found during the population peaks of omnivorous and herbivorous species. The population peaks of insectivorous species were found to occur much later in spring and considerably earlier in fall than the. corresponding peaks of omnivorous and herbivorous species. The Fringillidae contributed the greatest number of individuals in winter, while the Parulidae was the most important family (numerically) in summer. Water birds and marsh birds were relatively unimportant throughout the year, due to the scarcity of suitable habitats. Permanent resident species were found to vary from about one-fifth to slightly less than one-half of the total population throughout the year, although many individuals of these species were either transients or part-time residents. Summer residents and winter residents were more abundant than permanent residents during their respective periods of occurrence. During the greater part of the migration period, transient species were found to comprise only 10 to 20 percent of the total population. transient individuals of all species would account for a much larger proportion of the population at this time. After comparing the results of these investigations with similar studies in other areas, it is believed that the seasonal population changes on the Patuxent Research Refuge are fairly representative of those occurring throughout the Middle Atlantic and East-central States. Yearly variations in seasonal population changes are described and the causative factors indicated, when known. Of these, food supply and weather conditions were generally the m

Society of Environmental Toxicology and Chemistry,↗

USGS2015

Southern Salish Sea Habitat Map Series: Admiralty Inlet

In 2010 the Environmental Protection Agency, Region 10 initiated the Puget Sound Scientific Studies and Technical Investigations Assistance Program, designed to support research in support of implementing the Puget Sound Action Agenda. The Action Agenda was created in response to Puget Sound having been designated as one of 28 estuaries of national significance under section 320 of the U.S. Clean Water Act, and its overall goal is to restore the Puget Sound Estuary's environment by 2020. The Southern Salish Sea Mapping Project was funded by the Assistance Program request for proposals process, which also supports a large number of coastal-zone- and ocean-management issues. The issues include the recommendations of the Marine Protected Areas Work Group to the Washington State Legislature (Van Cleve and others, 2009), which endorses a Puget Sound and coast-wide marine conservation needs assessment, gap analysis of existing Marine Protected Areas (MPA) and recommendations for action. This publication is the first of four U.S. Geological Survey Scientific Investigation Maps that make up the Southern Salish Sea Mapping Project. The remaining three map blocks to be published in the future, located south of Admiralty Inlet, are shown in figure 1. Puget Sound is a deep, fjord-type estuary covering an area of 2,330 km 2 in the Pacific Northwest region of the United States (fig. 1). It is connected to the ocean by the Strait of Juan de Fuca, a turbulent passage approximately 160 km in length and 22 km wide at its west end, expanding to over 40 km wide at its east end (Thomson, 1994). During the Pleistocene, the area was occupied several times by lobes of continental ice, resulting in a complex basin-fill of glacial and interglacial deposits that are locally as thick as 1100 m (Johnson and others, 2001). The last glaciation, called the Fraser glaciation, began after 28,800±740 14 C yr B.P. when ice started a slow expansion (Clague, 1981). At peak advance the westward Juan de Fuca lobe reached the edge of the continental shelf through the Juan de Fuca Strait shortly before 14,460±200 14 C yr B.P. (Herzer and Bornhold, 1982). The southward Puget lobe advanced to its terminal position in Puget Sound by around 14,150 14 C yr B.P. (Porter and Swanson, 1998). Ice retreated from its maximum to northern Whidbey Island by 13,650±350 14 C yr B.P. (Dethier and others, 1995). Retreating glaciers resulted in a thick sequence of ice-contact, glacial-marine sediment, and early post-glacial sediments (Linden and Schurrer, 1988). These deposits have experienced the effects of a marine transgression followed by regression, resulting in a sea-level several tens of meters lower than the present day (Linden and Schurrer, 1988). A second transgression brought sea level to about the present level by around 5,470±120 14 C yr B.P. (Clague and others, 1982) establishing the present oceanographic and geologic environment Puget Sound is separated into four interconnected basins; Whidbey, Central (Main), Hood Canal, and South (Thomson, 1994). The Whidbey, Central, and Hood Canal basins are the three main branches of the Puget Sound estuary and are separated from the Strait of Juan de Fuca by a double sill at Admiralty Inlet. The Admiralty Inlet map area includes the Inlet and a portion of the Whidbey Basin (fig. 1). The shallower South Basin is separated by a sill at Tacoma Narrows and is highly branched with numerous finger inlets. Flow within Puget Sound is dominated by tidal currents of as much as 1 m/s at Admiralty Inlet, reducing to approximately 0.5 m/s in the Central Basin (Lavelle and others, 1988). The lack of silt and clay-sized sediments in the Admiralty Inlet map area is likely a result of the strong currents (see Ground-Truth Studies for the Admiralty Inlet Map Area, sheet 3). The subtidal component of flow reaches approximately 0.1 m/s and is driven by density gradients arising from the contrast in salty ocean water at the entrance and freshwater inputs from stream flow (Lavelle and others, 1988). The total freshwater input to Puget Sound is approximately 3.4 x 10 6 m 3 /day, primarily from the Skagit River (Cannon, 1983). The subtidal circulation mostly consists of a two-layered flow in the basins with fresher water exiting at the surface and saltier water entering at depth (Ebbesmeyer and Cannon, 2001). In general, surface waters flow north and deeper waters flow south; variations arise from wind effects that can drive a surface current in the same direction as the wind, and a baroclinic response in the lower layer to about 100-m depth (Matsuura and Cannon, 1997). Oceanographic properties are influenced by temporal forcing parameters such as reduced stream flow during the 2000-01 drought that increased surface salinity and decreased differences between surface and bottom waters (Newton and others, 2003). On offshore seismic-reflection profiles, Pleistocene strata (excluding latest Pleistocene glacial and post-glacial deposits) form a distinct seismic unit, bounded below by pre-Tertiary or Tertiary basement and above by typically flat-lying latest Pleistocene to Holocene deposits that fill in erosional or depositional relief (Johnson and others, 2001). Cores from central Puget Sound have accumulation rates that range from 85 to 1200 mg/cm 2 /yr, or 0.12 to 2.4 cm/yr; the highest accumulation rates are near the southern end of central Puget Sound (Carpenter and others, 1985). Carpenter and others (1985) un-weighted arithmetic mean of accumulation rates for central Puget Sound deeper stations is 480±340 (± one standard deviation) mg/cm 2 /yr. Lavelle and others (1985) also found rates as high as 1200 mg/cm 2 /yr over the past approximately 70 years in cores in the Central Basin off of and north and south of Elliott Bay. Puget Sound basin rates are comparable to rates in midshelf silt deposits on the Washington coast north of the Columbia River (Nittrouer and others, 1979). The deep subtidal (in other words, below SCUBA depths) habitats of Puget Sound are relatively poorly known. A few subtidal surveys exist for several habitat types from the 1960s and 1970s (reviewed in Dethier, 1990), using grab and box core data. The Dethier (1990) review divides habitat up into Coast and Marine Ecological Classification Standard (CMECS) substrate, water column energy, and depth zones but does not attempt to map these habitats, rather it is an inventory of habitats found in the area and the flora and fauna associated with each habitat. The approach of the Southern Salish Sea Mapping project is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data (the undersea equivalent of satellite remote-sensing data in terrestrial mapping), acoustic backscatter, seafloor video, seafloor photography, and bottom-sediment sampling data. This approach is based in part on methods presented and data collection and product needs identified at the Washington State Seafloor Mapping Workshop (Washington State Seafloor Mapping Workshop Steering Committee, 2008), attended by coastal and marine managers and scientists. The map products display seafloor geomorphology and substrate, and identify potential marine benthic habitats. It is emphasized that the more interpretive habitat and geology maps rely on the integration of multiple, new high-resolution datasets and that mapping at small scales would not be possible without such data. Oceanographic current and wave data is not included in this analysis, however, the accompanying geographic information system (GIS) data set is designed and intended to be combined with oceanographic and biologic data sets assembled by others in the future and some of the GIS data has already been incorporated in the unpublished Nature Conservancy Benthic Habitats of Puget Sound database. This publication includes four map sheets, explanatory text, and a descriptive pamphlet. Each map sheet is published as a portable document format (PDF) file. ESRI ArcGIS compatible geotiffs (for example, bathymetry) and shapefiles (for example video observation points) will be available for download in the data catalog associated with this publication (Cochrane, 2015). An ArcGIS Project File with the symbology used to generate the map sheets is also provided. For those who do not own the full suite of ESRI GIS and mapping software, the data can be read using ESRI ArcReader, a free viewer that is available at http://www.esri.com/software/arcgis/arcreader/index.html .

Washington↗