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USGS2010

Estimation of selected streamflow statistics for a network of low-flow partial-record stations in areas affected by Base Realignment and Closure (BRAC) in Maryland

The U.S. Geological Survey, in cooperation with the Maryland Department of the Environment, operated a network of 20 low-flow partial-record stations during 2008 in a region that extends from southwest of Baltimore to the northeastern corner of Maryland to obtain estimates of selected streamflow statistics at the station locations. The study area is expected to face a substantial influx of new residents and businesses as a result of military and civilian personnel transfers associated with the Federal Base Realignment and Closure Act of 2005. The estimated streamflow statistics, which include monthly 85-percent duration flows, the 10-year recurrence-interval minimum base flow, and the 7-day, 10-year low flow, are needed to provide a better understanding of the availability of water resources in the area to be affected by base-realignment activities. Streamflow measurements collected for this study at the low-flow partial-record stations and measurements collected previously for 8 of the 20 stations were related to concurrent daily flows at nearby index streamgages to estimate the streamflow statistics. Three methods were used to estimate the streamflow statistics and two methods were used to select the index streamgages. Of the three methods used to estimate the streamflow statistics, two of them--the Moments and MOVE1 methods--rely on correlating the streamflow measurements at the low-flow partial-record stations with concurrent streamflows at nearby, hydrologically similar index streamgages to determine the estimates. These methods, recommended for use by the U.S. Geological Survey, generally require about 10 streamflow measurements at the low-flow partial-record station. The third method transfers the streamflow statistics from the index streamgage to the partial-record station based on the average of the ratios of the measured streamflows at the partial-record station to the concurrent streamflows at the index streamgage. This method can be used with as few as one pair of streamflow measurements made on a single streamflow recession at the low-flow partial-record station, although additional pairs of measurements will increase the accuracy of the estimates. Errors associated with the two correlation methods generally were lower than the errors associated with the flow-ratio method, but the advantages of the flow-ratio method are that it can produce reasonably accurate estimates from streamflow measurements much faster and at lower cost than estimates obtained using the correlation methods. The two index-streamgage selection methods were (1) selection based on the highest correlation coefficient between the low-flow partial-record station and the index streamgages, and (2) selection based on Euclidean distance, where the Euclidean distance was computed as a function of geographic proximity and the basin characteristics: drainage area, percentage of forested area, percentage of impervious area, and the base-flow recession time constant, t. Method 1 generally selected index streamgages that were significantly closer to the low-flow partial-record stations than method 2. The errors associated with the estimated streamflow statistics generally were lower for method 1 than for method 2, but the differences were not statistically significant. The flow-ratio method for estimating streamflow statistics at low-flow partial-record stations was shown to be independent from the two correlation-based estimation methods. As a result, final estimates were determined for eight low-flow partial-record stations by weighting estimates from the flow-ratio method with estimates from one of the two correlation methods according to the respective variances of the estimates. Average standard errors of estimate for the final estimates ranged from 90.0 to 7.0 percent, with an average value of 26.5 percent. Average standard errors of estimate for the weighted estimates were, on average, 4.3 percent less than the best average standard errors of estima

Scientific Investigations Report↗

USGS2011

Improvement in precipitation-runoff model simulations by recalibration with basin-specific data, and subsequent model applications, Onondaga Lake Basin, Onondaga County, New York

Water-resource managers in Onondaga County, New York, are faced with the challenge of improving the water quality of Onondaga Lake, which has the distinction of being one of the most contaminated lakes in the United States. To assist in this endeavor, during 2003-07 the U.S. Geological Survey (USGS), in cooperation with the Onondaga Lake Partnership, developed a precipitation-runoff model of the 285-square-mile Onondaga Lake Basin with the computer program Hydrological Simulation Program-Fortran (HSPF). The model was intended to provide a tool whereby the processes responsible for the generation of loads of sediment and nutrients that are transported to Onondaga Lake could be better understood. This objective was only partly attained because data for calibration of the model were available from monitoring sites only at or near the mouths of the major tributaries to Onondaga Lake; no calibration data from headwater subbasins, where the loads originated, were available. To address this limitation and thereby decrease the uncertainty in the simulated results that were associated with headwater processes, the USGS conducted a 3-year (2005-08) basinwide study to assess the quality of surface water in the Onondaga Lake Basin. The study quantified the relative contributions of nonpoint sources associated with the major land uses and land covers in the basin and also monitored known sources and presumed sinks of sediment and nutrient loads, which previously had not been evaluated. The use of the newly acquired data to recalibrate the HSPF model resulted in improvements in the simulation of processes in the headwater subbasins, including suspended-sediment, orthophosphate, and phosphorus generation and transport. Simulation of streamflows in small subbasins was improved by adjusting model parameter values to match base flows, storm peaks, and storm recessions more precisely than had been done with the original model. Simulated recessional and low flows were either increased or decreased as appropriate for a given stream, and simulated peak flows generally were lowered in the revised model. The use of suspended-sediment concentrations rather than concentrations of the surrogate constituent, total suspended solids, resulted in increases in the simulated low-flow sediment concentrations and, in most cases, decreases in the simulated peak-flow sediment concentrations. Simulated orthophosphate concentrations in base flows generally increased but decreased for peak flows in selected headwater subbasins in the revised model. Compared with the original model, phosphorus concentrations simulated by the revised model were comparable in forested subbasins, generally decreased in developed and wetland-dominated subbasins, and increased in agricultural subbasins. A final revision to the model was made by the addition of the simulation of chloride (salt) concentrations in the Onondaga Creek Basin to help water-resource managers better understand the relative contributions of salt from multiple sources in this particular tributary. The calibrated revised model was used to (1) compute loading rates for the various land types that were simulated in the model, (2) conduct a watershed-management analysis that estimated the portion of the total load that was likely to be transported to Onondaga Lake from each of the modeled subbasins, (3) compute and assess chloride loads to Onondaga Lake from the Onondaga Creek Basin, and (4) simulate precolonization (forested) conditions in the basin to estimate the probable minimum phosphorus loads to the lake.

Onondaga, New York↗

USGS2013

Science-based management of public lands in southern Nevada

Landmark legislation provides guiding principles for land management planning in southern Nevada and the rest of the United States. Such legislation includes, but is not limited to, the Forest Service Organic Administration Act of 1897 (16 U.S>C. 473-478, 479-482 and 551), National Park Service Organic Act of 1916 (U.S.C. Title 16, Secs. 1-4). Wilderness Act 1964 (P.L.88-577), National Environmental Policy Act of 1969 (P.L. 91-190), Endangered Species Act of 1973 (P.L. 91-205), National Forest Management Act of of 1976 (P.L. 94-588), and Federal Land Policy and Management Act of 1976 (P.L. 94-579). The acts establishing congressionally designated areas within southern Nevada, such as Lake Mead National Recreation Area, Spring Mountains National Restoration Area, and Desert National Wildlife Refuge, also contain guidelines for the management of these lands. These documents variously require preservation of natural and cultural resource and wilderness character, protection of species, and prevention of undesirable environmental effects from land management actions. These requirements must be met while allowing for multiple "uses" of certain public lands (e.g. recreation, ranching, resources extraction, renewable energy development, etc.) to the degree that they do no threaten preservation, protection, and prevention goals,. many considerations some into play in the development and implementation for land management plans and actions. The planning process requires a balancing act that sometimes pit one need or priority against another. When priorities can trump other needs can prioritized and receive disproportionate consideration. Overall, the management of public lands is a very complicated and sometime contentious process. Science provides an objective way to help weigh quantifiable information and draw conclusions about the effects of past and potential future land management policies, decisions, and actions. When effectively integrated into adaptive management, science-based information can reduce uncertainties, increase knowledge, and improve decision making. However, the specific science information needed for effective management is often lacking or difficult to access or interpret. Science is typically reported in scientific journals as discrete units describing individual studies with other scientists as the primary audience. Translations of these studies an synthesis or multiple studies into formats that can be readily used in land management planning efforts are often lacking. Identifying and articulating the highest priority science and research needs is one of the primary purposes of the Southern Nevada Agency Partnership (SNAP; http://www.SNAP.gov) Science and Research Team (chapter 1; Turner and others 2009). The SNAP Science and Research Strategy (Strategy) calls for a synthesis report to be written every 5 years summarizing the state of knowledge, information gaps and management implications of scientific information as it relates to the SNAP Strategy goals (Turner and others 2009). This General Technical Report serves as the first SNAP Science and Research Synthesis Report (Synthesis Report) commissioned by the Science and Research Team. The Synthesis Report is mostly based on information form the peer-reviewed scientific literature, and is itself peer reviewed and constitutes a new contribution to the scientific literature. This final chapter addresses Sub-goal 2.3, which is to manage current and future authorized southern Nevada land uses in a manner that balances public need and ecosystem sustainability, and Sub-goal 2.5, which is to promote an effective conservation education and interpretation program to improve the quality of resources and enhance public use and enjoyment of southern Nevada public lands. It summarizes information form the previous chapters on what scientific information is known currently and what remains largely unknown, and it discusses how science can be used to make future management decisions that balances public needs and ecosystem sustainability.

Nevada↗

USGS2019

Multi-resource analysis: A proof of concept study of natural resource tradeoffs in the Piceance Basin, Colorado, using the net resources assessment (NetRA) decision support tool

Executive Summary The U.S. Geological Survey (USGS) is developing a multi-resource analysis (MRA) line of products to inform land-use decision makers. Specifically, MRA products will integrate scientific information, include considerations for natural resource interrelations, and quantify the effects of resource management decisions in biophysical, economic, and societal terms. As part of the establishment of the MRA, the USGS, in collaboration with the University of New Mexico, has developed the Net Resources Assessment (NetRA) decision support tool. As a proof of concept analysis, the NetRA was applied to the Piceance basin in Colorado in a hypothetical example to illustrate how resource managers could use the NetRA to consider tradeoffs of natural resources among alternative development plans and land cover patterns within a geographic region. The NetRA is a policy-relevant approach to assess the availability of multiple natural resources. It is an analytical toolset that may be used to examine the spatiotemporal relations between development of energy and mineral resources and delivery of biological natural resources. The NetRA operates at multiple map scales and contains a set of integrated, compatible submodels with specific data requirements for natural resource stocks, engineering economics, biophysical, and ecological data for ecosystem services stocks, market prices, regulations, and nonmarket values. The NetRA includes an explicit process to consider the interdependence between development and conservation, which is a crucial consideration in land-management and land-use decisions. The NetRA is used to estimate an expected net resource value (NRV). The NRV is the expected, present value, economic benefit from the extraction of a resource (for example, natural gas) minus the total cost of production, which is the aggregation of the development, production, and social costs. Social costs include private costs plus any external costs. There can be external social benefits associated with natural gas production, such as increased demand for locally produced goods and increased employment in the local area through backward and forward linkages of natural gas production. The NRV is used to compare development outcomes (scenarios) from a range of exploration and development plans for cumulative energy production. The Piceance basin application of the NetRA uses the NRV to assess the tradeoff between continuous natural gas extraction and the effects to the local populations of Odocoileus hemionus (mule deer) and aquatic species and to consumptive water uses for an area the size and resolution of a USGS energy resource assessment unit. In the proof of concept simulation, the 2.9-square-mile-area of USGS oil and gas assessment unit 50200263 (Piceance basin continuous gas unit of the Mesaverde Total Petroleum System) was gridded into 588 cells. From this area, seven clusters with potential for development and three that cannot be developed were identified; the three clusters that cannot be developed were identified as wilderness study areas, areas of critical environmental concern, and national forests. On the basis of these criteria, there are 118 cells unsuitable for development in the oil and gas assessment unit: 84 are in national forests, 23 are areas of critical environmental concern, and 11 are wilderness study areas. The remaining cells in the oil and gas assessment unit can be developed on both private and public lands. Two scenarios were considered that are distinguished as plan 1 and plan 2. Plan 1 keeps the amount of land disturbance unchanged and limits the number of development locations to 140 grid cells for the production period, which constrains the amount of the energy resources available for development; the plan requires the usage of the Bureau of Land Management (BLM) unsuitability criteria. Plan 2 also limits the number of development locations to 140 grid cells for the production period but provides a constant volume of energy production by increasing the density of well pads within the cells. The effects of plan 2 to the NRV when there are five wells per pad and five pads per square mile happen mostly in the first 5 years of development, even though the effects on the population of mule deer continue in later years. This outcome is the result of the upfront development and investment costs and the initial effect to the ecosystem services.

Colorado↗

USGS2017

Integrated wetland management for waterfowl and shorebirds at Mattamuskeet National Wildlife Refuge, North Carolina

Mattamuskeet National Wildlife Refuge (MNWR) offers a mix of open water, marsh, forest, and cropland habitats on 20,307 hectares in coastal North Carolina. In 1934, Federal legislation (Executive Order 6924) established MNWR to benefit wintering waterfowl and other migratory bird species. On an annual basis, the refuge staff decide how to manage 14 impoundments to benefit not only waterfowl during the nonbreeding season, but also shorebirds during fall and spring migration. In making these decisions, the challenge is to select a portfolio, or collection, of management actions for the impoundments that optimizes use by the three groups of birds while respecting budget constraints. In this study, a decision support tool was developed for these annual management decisions. Within the decision framework, there are three different management objectives: shorebird-use days during fall and spring migrations, and waterfowl-use days during the nonbreeding season. Sixteen potential management actions were identified for impoundments; each action represents a combination of hydroperiod and vegetation manipulation. Example hydroperiods include semi-permanent and seasonal drawdowns, and vegetation manipulations include mechanical-chemical treatment, burning, disking, and no action. Expert elicitation was used to build a Bayesian Belief Network (BBN) model that predicts shorebird- and waterfowl-use days for each potential management action. The BBN was parameterized for a representative impoundment, MI-9, and predictions were re-scaled for this impoundment to predict outcomes at other impoundments on the basis of size. Parameter estimates in the BBN model can be updated using observations from ongoing monitoring that is part of the Integrated Waterbird Management and Monitoring (IWMM) program. The optimal portfolio of management actions depends on the importance, that is, weights, assigned to the three objectives, as well as the budget. Five scenarios with a variety of objective weights and budgets were developed. Given the large number of possible portfolios (16 14 ), a heuristic genetic algorithm was used to identify a management action portfolio that maximized use-day objectives while respecting budget constraints. The genetic algorithm identified a portfolio of management actions for each of the five scenarios, enabling refuge staff to explore the sensitivity of their management decisions to objective weights and budget constraints. The decision framework developed here provides a transparent, defensible, and testable foundation for decision making at MNWR. The BBN model explicitly structures and parameterizes a mental model previously used by an expert to assign management actions to the impoundments. With ongoing IWMM monitoring, predictions from the model can be tested, and model parameters updated, to reflect empirical observations. This framework is intended to be a living document that can be updated to reflect changes in the decision context (for example, new objectives or constraints, or new models to compete with the current BBN model). Rather than a mandate to refuge staff, this framework is intended to be a decision support tool; tool outputs can become part of the deliberations of refuge staff when making difficult management decisions for multiple objectives.

North Carolina↗

USGS2014

Concentrations, loads, and yields of total nitrogen and total phosphorus in the Barnegat Bay-Little Egg Harbor watershed, New Jersey, 1989-2011, at multiple spatial scales

Concentrations, loads, and yields of nutrients (total nitrogen and total phosphorus) were calculated for the Barnegat Bay-Little Egg Harbor (BB-LEH) watershed for 1989–2011 at annual and seasonal (growing and nongrowing) time scales. Concentrations, loads, and yields were calculated at three spatial scales: for each of the 81 subbasins specified by 14-digit hydrologic unit codes (HUC-14s); for each of the three BB-LEH watershed segments, which coincide with segmentation of the BB-LEH estuary; and for the entire BB-LEH watershed. Base-flow and runoff values were calculated separately and were combined to provide total values. Available surface-water-quality data for all streams in the BB-LEH watershed for 1980–2011 were compiled from existing datasets and quality assured. Precipitation and streamflow data were used to distinguish between water-quality samples that were collected during base-flow conditions and those that were collected during runoff conditions. Base-flow separation of hydrographs of six streams in the BB-LEH watershed indicated that base flow accounts for about 72 to 94 percent of total flow in streams in the watershed. Base-flow mean concentrations (BMCs) of total nitrogen (TN) and total phosphorus (TP) for each HUC-14 subbasin were calculated from relations between land use and measured base-flow concentrations. These relations were developed from multiple linear regression models determined from water-quality data collected at sampling stations in the BB-LEH watershed under base-flow conditions and land-use percentages in the contributing drainage basins. The total watershed base-flow volume was estimated for each year and season from continuous streamflow records for 1989–2011 and relations between precipitation and streamflow during base-flow conditions. For each year and season, the base-flow load and yield were then calculated for each HUC-14 subbasin from the BMCs, total base-flow volume, and drainage area. The watershed-loading application PLOAD was used to calculate runoff concentrations, loads, and yields of TN and TP at the HUC-14 scale. Flow-weighted event-mean concentrations (EMCs) for runoff were developed for each major land-use type in the watershed using storm sampling data from four streams in the BB-LEH watershed and three streams outside the watershed. The EMCs were developed separately for the growing and nongrowing seasons, and were typically greater during the growing season. The EMCs, along with annual and seasonal precipitation amounts and percent imperviousness associated with land-use types, were used as inputs to PLOAD to calculate annual and seasonal runoff concentrations, loads, and yields at the HUC-14 scale. Over the period of study (1989–2011), total surface-water loads (base flow plus runoff) for the entire BB-LEH watershed for TN ranged from about 455,000 kilograms (kg) as N (1995) to 857,000 kg as N (2010). For TP, total loads for the watershed ranged from about 17,000 (1995) to 32,000 kg as P (2010). On average, the north segment accounted for about 66 percent of the annual TN load and 63 percent of the annual TP load, and the central and south segments each accounted for less than 20 percent of the nutrient loads. Loads and yields were strongly associated with precipitation patterns, ensuing hydrologic conditions, and land use. HUC-14 subbasins with the highest yields of nutrients are concentrated in the northern part of the watershed, and have the highest percentages of urban or agricultural land use. Subbasins with the lowest TN and TP yields are dominated by forest cover. Percentages of turf (lawn) cover and nonturf cover were estimated for the watershed. Of the developed land in the watershed, nearly one quarter (24.9 percent) was mapped as turf cover. Because there is a strong relation between percent turf and percent developed land, percent turf in the watershed typically increases with percent development, and the amount of development can be considered a reasonable predictor of the amount of turf cover in the watershed. In the BB-LEH watershed, calculated concentrations of TN and TP were greater for developed–turf areas than for developed–nonturf areas, which, in turn, were greater than those for undeveloped areas.

New Jersey↗

USGS2018

Drivers and mechanisms of tree mortality in moist tropical forests

Tree mortality rates appear to be increasing in moist tropical forests (MTFs) with significant carbon cycle consequences. Here, we review the state of knowledge regarding MTF tree mortality, create a conceptual framework with testable hypotheses regarding the drivers, mechanisms and interactions that may underlie increasing MTF mortality rates, and identify the next steps for improved understanding and reduced prediction. Increasing mortality rates are associated with rising temperature and vapor pressure deficit, liana abundance, drought, wind events, fire and, possibly, CO 2 fertilization‐induced increases in stand thinning or acceleration of trees reaching larger, more vulnerable heights. The majority of these mortality drivers may kill trees in part through carbon starvation and hydraulic failure. The relative importance of each driver is unknown. High species diversity may buffer MTFs against large‐scale mortality events, but recent and expected trends in mortality drivers give reason for concern regarding increasing mortality within MTFs. Models of tropical tree mortality are advancing the representation of hydraulics, carbon and demography, but require more empirical knowledge regarding the most common drivers and their subsequent mechanisms. We outline critical datasets and model developments required to test hypotheses regarding the underlying causes of increasing MTF mortality rates, and improve prediction of future mortality under climate change.

New Phytologist↗

USGS2011

Canine detection of free-ranging brown treesnakes on Guam

We investigated canine teams (dogs and their handlers) on Guam as a potential tool for finding invasive brown treesnakes (Boiga irregularis) in the wild. Canine teams searched a 40 × 40 m forested area for a snake that had consumed a dead mouse containing a radio-transmitter. To avoid tainting the target or target area with human scent, no snake was handled or closely approached prior to searches. Trials were conducted during the morning when these nocturnal snakes were usually hidden in refugia. A radiotracker knew the snake's location, but dog handlers and search navigators did not. Of 85 trials conducted over four months, the two canine teams had an average success rate of 35% of correctly defining an area ≤ 5 × 5 m that contained the transmittered snake; the team with more experience prior to the trials had a success rate of 44% compared with 26% for the less experienced team. Canine teams also found 11 shed skins from wild snakes. Although dogs alerted outside the vicinity of transmittered snakes, only one wild, non-transmittered snake was found during the trials, possibly reflecting the difficulty humans have in locating non-transmittered brown treesnakes in refugia. We evaluated success at finding snakes as a function of canine team, number of prior trials (i.e. experience gained during the trials), recent canine success at finding a target snake, various environmental conditions, snake perch height, and snake characteristics (snout-vent length and sex). Success rate increased over the course of the trials. Canine team success also increased with increasing average humidity and decreased with increasing average wind speed. Our results suggest dogs could be useful at detecting brown treesnakes in refugia, particularly when compared to daytime visual searches by humans, but techniques are needed to help humans find and extract snakes once a dog has alerted.

New Zealand Journal of Ecology↗

USGS2021

The water quality of selected streams in the Catskill and Delaware water-supply watersheds in New York, 1999–2009

From October 1, 1999, through September 30, 2009, water-quality samples were collected, and discharge was measured at 13 streamgages within the Catskill and Delaware watersheds of the New York City water supply system. The Catskill and Delaware watersheds supply about 90 percent of the water needed by 9 million customers. On average, 59 water-quality samples were collected at each station during each year of the study and analyzed for major ions and nutrients. At six stations, suspended-sediment samples were collected during 2001–09, and turbidity samples were collected during 2003–09. Surficial geology exerted a strong influence on the water quality of streams in the region. Stations in the Cannonsville Reservoir watershed, which has a high percentage of glacial till, had circumneutral stream water, whereas stations in the Neversink Reservoir watershed, which has a high percentage of sedimentary bedrock outcrops, had acidic stream water. All stations showed significant decreases in stream water sulfate concentrations during the study period; however, only the most acidic watersheds showed decreases in hydrogen-ion concentration. Two of the most acidic stations, East Branch Neversink River northeast of Denning and Rondout Creek above Red Brook at Peekamoose also had significant decreasing trends in inorganic monomeric aluminum concentrations, a form of aluminum that is toxic to some aquatic biota at concentrations greater than 0.05 milligram per liter. Three stations in the Neversink Reservoir watershed had inorganic monomeric aluminum concentrations that commonly exceeded 0.05 milligram per liter during the study period. At the West Branch Neversink River at Winnisook Lake near Frost Valley station concentrations of inorganic monomeric aluminum exceeded 0.3 milligram per liter at the beginning of the study, but never exceeded that level during the last 2 water years of the study. The East Branch Neversink River northeast of Denning and Rondout Creek above Red Brook at Peekamoose stations also showed decreases in inorganic monomeric aluminum concentrations during the study. The reduction in inorganic monomeric aluminum concentrations were the result of reductions in stream acidity. The reductions in stream acidity were driven by reductions in sulfate concentrations in precipitation in response to emission regulations included in title IV of the Clean Air Act Amendments of 1990 (42 USC §7651). Results indicated increasing trends in sodium and chloride concentrations for all stations with high road density relative to other stations included in the study, which could be a future water-quality concern in the region. The Town Brook watershed southeast of Hobart, the only study watershed that contained dairy farms, had a significant decreasing trend in total dissolved phosphorus concentration that may have been a result of agricultural best management practices implemented on farms by the Watershed Agricultural Program. The watershed with the second highest total phosphorus and total dissolved phosphorus concentrations was a completely forested, but previously agricultural, watershed (Town Brook tributary southeast of Hobart) that had not been actively farmed in about 80 years. The phosphorus concentrations at the Town Brook tributary southeast of Hobart station indicated that previously agricultural watersheds may continue to leach phosphorus to streams for many decades after farming has ceased. At six of the study watersheds, samples of suspended-sediment and turbidity were also collected. The watersheds with the highest suspended-sediment concentrations and turbidity also had the strongest relations between discharge and suspended-sediment concentrations. In general, the relations between discharge and turbidity were not as strong as the relations between discharge and suspended-sediment concentrations. Results indicated strong relations between suspended-sediment concentrations and turbidity levels at each station; however, relations were less strong in the agricultural watersheds. Suspended-sediment concentrations appeared to decrease at the Stony Clove Creek below Ox Clove at Chichester station following a stream stabilization project completed during the study period. However, we were unable to directly attribute the decrease to the stabilization project; there were many complicating variables that made a direct attribution difficult, such as a series of large storms shortly after the stabilization project was completed and differences in flow conditions before and after the project. However, the results have led to additional monitoring within the watershed specifically designed to determine the effectiveness of stream stabilization projects for reducing suspended-sediment concentrations and turbidity in the upper Esopus Creek watershed, the primary source of water to the Ashokan Reservoir. Water quality in the Catskill and Delaware watersheds is generally improving, and although sodium and chloride concentrations increased at some of the stations from 1999 to 2009, the concentrations in 2009 were still well below U.S. Environmental Protection Agency drinking water standards.

New York↗

USGS2007

Status review of the Marbled Murrelet (Brachyramphus marmoratus) in Alaska and British Columbia

The Marbled Murrelet ( Brachyramphus marmoratus ) is a small, diving seabird inhabiting inshore waters of the Northeastern Pacific Ocean. This species feeds on small, schooling fishes and zooplankton, and nests primarily on the moss-covered branches of large, old-growth conifers, and also, in some parts of its range, on the ground. We reviewed existing information on this species to evaluate its current status in the northern part of its range—Alaska (U.S.) and British Columbia (Canada). Within the southern part of its range (Washington, Oregon, and California, U.S.), the Marbled Murrelet was listed as a threatened species under the Endangered Species Act (ESA) in 1993, and the U.S. Fish and Wildlife Service (USFWS) needed information on the species throughout its range for ESA deliberations. We compiled published information on the conservation status, population biology, foraging ecology, population genetics, population status and trends, demography, marine and nesting habitat characteristics, threats, and ongoing conservation efforts for Marbled Murrelets in Alaska and British Columbia. We conducted a new genetic study using samples from a segment of the range that had not been included in previous studies (Washington, Oregon) and additional nuclear intron and microsatellite markers. We also analyzed available at-sea survey data from several locations for trend. To understand the reasonableness of the empirical trend data, we developed demographic models incorporating stochasticity to discern what population trends were possible by chance. The genetic studies substantially confirmed previous findings on population structure in the Marbled Murrelet. Our present work finds three populations: (1) one comprising birds in the central and western Aleutian Islands; (2) one comprising birds in central California; and (3) one comprising birds within the center of the range from the eastern Aleutians to northern California. Our knowledge of genetic structure within this central population is limited and it requires additional study. Compiling available abundance information, we estimated that in the recent past, Marbled Murrelets in Alaska numbered on the order of 1 million birds. We were unable to generate a similar estimate for historical population size in British Columbia. Using trend information from at-sea surveys spanning a wide geographic range in Alaska, murrelet numbers declined significantly at five of eight trend sites at annual rates of -5.4 to -12.7 percent since the early 1990s. Applying these rates of decline to the historical population estimate, the current murrelet population in Alaska is projected to be on the order of 270,000 birds. This represents an overall population decline of about 70 percent during the past 25 years. In British Columbia, available trend data indicate that murrelet populations there have experienced similar declines. We updated a recent (2002) population estimate for British Columbia, concluding that there are now between 54,000 and 92,000 murrelets in British Columbia. The rates of decline we observed are within, but at the high end of, a range of rates expected by chance. Given that declines were estimated for sites over essentially the entire northern range of the species, there is cause for concern about the species’ status. In their marine habitats, Marbled Murrelets overlap with salmon (Oncorhynchus sp.) gillnetting operations in British Columbia and in Alaska (especially in Prince William Sound and Southeast Alaska), and annual bycatch mortality is likely in the low thousands per year, although bycatch rates are difficult to measure. The species’ inshore distribution coincides with high levels of vessel traffic and makes them especially vulnerable to both chronic oil pollution and to catastrophic spills (e.g., the 1989 Exxon Valdez oil spill [EVOS] in south-central Alaska, which is estimated to have killed 12,000 to 15,000 murrelets). In their forested nesting habitats, Marbled Murrelets have lost about 15 percent of their suitable nesting habitat in Southeast Alaska, and 33 to 49 percent in British Columbia, from industrial-scale logging within the past half century. Increased predation also may be a threat to murrelet populations, related to fragmentation and edge effects from logging and development, and recent population increases observed for some important murrelet predators, including Bald Eagles ( Haliaeetus leucocephalus ), Common Ravens ( Corvus corax ), and Steller’s Jays ( Cyanocitta stelleri ). Nesting habitat losses cannot explain the declines observed in areas where industrial logging has not occurred on a large scale (e.g., Prince William Sound) or at all (Glacier Bay). The apparent change in population size and rates of decline reported for the Marbled Murrelet are large, and we therefore considered alternative explanations and precedents for changes of similar magnitude in other marine wildlife populations in the Northeastern Pacific Ocean. The declines are likely real, and related to combined and cumulative effects from climate-related changes in the marine ecosystem (most likely the 1977 regime shift) and human activities (logging, gillnet bycatch, oil pollution). Much uncertainty about the decline could be alleviated by continuing to repeat boat surveys in Prince William Sound and lower Cook Inlet, and by repeating the boat survey of Southeast Alaska that was conducted in 1994. This survey used a statistically sound design and covered the region that has been and likely remains the center of the species’ abundance. Important questions remain to be addressed about methods for measuring population status and change, adult mortality (major sources, density dependence, seasonal concordance), and the movements of wintering populations.

Alaska, British Columbia↗

USGS2003

Aquatic assemblages and their relation to temperature variables of least-disturbed streams in the Salmon River basin, central Idaho, 2001

In the late 1990s, Idaho’s established stream temperature criteria for the protection of coldwater biota and salmonid spawning were considered inadequate because the criteria did not agree with observed biological conditions in many instances and did not allow for variability in environmental condition or species diversity across a broad area such as the entire State of Idaho. In 2001, benthic invertebrate and fish assemblages in 34 least-disturbed streams in the Salmon River Basin, central Idaho, were evaluated in relation to stream temperature and other environmental variables. The Salmon River Basin retains watersheds that are minimally affected by human activities. These “natural” stream conditions provide a basis for deriving attainable stream temperatures that can be used to set new, and revise existing, water-quality criteria for stream habitats affected by human activities. During July through September 2001, data were collected to document the thermal regime of least-disturbed streams, characterize the distribution of aquatic biota at streams representing a gradient of temperature, and describe the relations between environmental variables and benthic invertebrate and fish assemblages. Nine stream temperature metrics were compared with the U.S. Environmental Protection Agency’s criterion of 10 ° C (degrees Celsius) for bull trout spawning and juvenile rearing. The maximum weekly-maximum temperature at all 33 sites where temperature data were available exceeded this criterion. The maximum daily-maximum temperature (MDMT) at 30 of the sites exceeded the Idaho Department of Environmental Quality (IDEQ) criterion of 13.0 ° C for the protection of salmonid spawning; and the maximum daily-average temperature at all 33 sites exceeded the 9.0 ° C criterion for the protection of salmonid spawning. The thermal regime at most sites did not exceed the IDEQ criteria for the protection of coldwater biota. Nine environmental variables—water-surface gradient, discharge, wetted channel width, width:depth ratio, aspect, total seasonal thermal input, open canopy, riparian canopy density, and elevation were selected for correlation with the nine stream temperature metrics. Elevation showed the strongest inverse correlation with the stream temperature metrics. Two hundred and one benthic invertebrate taxa from the 34 sampling sites were identified. The most abundant taxa were Baetis tricaudatus , Oligochaeta, Tvetenia bavarica gr., Acari, Rhithrogena , Cinygmula , Heterlimnius , Micropsectra , Eukiefferiella devonica gr., Drunella doddsi , and Cricotopus . Of the 201 benthic invertebrate taxa collected during this study, 57 taxa (present at a minimum of 5 sampling sites) were significantly correlated with one or more of the stream temperature metrics. Among the invertebrate taxa collected, 32 were identified as coldwater taxa. Of the coldwater taxa collected, Zapada oregonensis gr. showed the strongest inverse correlation with the stream temperature metrics and was collected at sites where maximum weekly-maximum temperature (based on date of sample and 6 days prior) ranged from 11.3 ° to 18.5 °C. Ten species of fish in the families Salmonidae, Cottidae, and Cyprinidae were collected. Two species (bull trout and chinook salmon) listed as threatened under the U.S. Fish and Wildlife Service Endangered Species Act were collected. Among all species, bull trout showed the strongest inverse correlation between relative fish abundance and stream temperature. Bull trout and juvenile bull trout densities were inversely correlated with stream temperature. The probability of occurrence of juvenile bull trout was significantly correlated with MDMT on the basis of results from a logistic regression model developed during this study. However, this model differed from a similar model developed by the U.S. Forest Service on the basis of regional data collected in the Pacific Northwest. The regression model based on data collected during this study showed higher probabilities of occurrence of bull trout at colder stream temperatures (10 ° to 15 ° C) and lower probabilities of occurrence at warmer stream temperatures (16 ° to 21 ° C) than did the model based on regional data. The model comparisons suggest that regional or local differences need to be considered when deriving stream temperature criteria.

Idaho↗

USGS2021

Effectiveness of rapid 'ōhi'a death management strategies at a focal disease outbreak on Hawai'i Island

The ongoing spread of rapid ‘ōhi‘a death (ROD) in the Hawaiian Islands threatens the long-term sustainability of ‘ōhi‘a lehua (Metrosideros polymorpha) forests throughout the state. First identified in the Puna district of Hawai‘i Island in 2014, the disease caused by the novel fungi Ceratocystis lukuohia and Ceratocystis huliohia has now spread island-wide and was recently detected on Kaua‘i, O‘ahu, and Maui. The leading hypothesis for the spread of ROD is through airborne ambrosia beetle frass particles that contain viable Ceratocystis propagules, thus management efforts focus on containing this frass. At the time of this study (2017–2018), the Waipunalei site was the northernmost outbreak of ROD on Hawai‘i Island. The focal nature of the outbreak and accessibility of the location provided the opportunity to monitor the effectiveness of two types of proposed management methods to reduce the airborne spread of potentially infective ambrosia beetle frass: tree felling and insecticide treatments. We placed 23 passive environmental samplers (PES), which monitored for airborne frass and wood particles containing C. lukuohia and C. huliohia in a grid that spanned the outbreak area over 22 weeks. Cross-vane panel traps with 1:1 methanol:ethanol lures were attached to nine of the PES to document wood-boring ambrosia and cerambycid beetle populations during the latter three months of the study. Monitoring with PES began three weeks before management and continued for one month after the last infected trees were felled. Glass microscope slides from the 23 PES were examined for airborne ambrosia beetle frass and wood particles by microscopy. DNA was extracted from the slides and tested by qPCR (quantitative polymerase chain reaction) for C. lukuohia and C. huliohia. We also investigated the correlation of beetle gallery counts with tree height and tested the efficacy of Bifen I/T insecticide (active ingredient: bifenthrin 7.9%) for preventing beetle attacks on the cut surface of ‘ōhi‘a bolts (tree stem sections). Beetle trapping data revealed that the area supports a diverse community of wood-boring beetles, some of which likely attack ‘ōhi‘a and may facilitate the spread of ROD. The number of beetle galleries on felled ‘ōhi‘a trees decreased linearly as tree height increased. We also observed significantly fewer beetle attacks on Bifen I/T treated ‘ōhi‘a bolts than non-treated bolts, but gallery formation nearly ceased in both treated and control bolts by week three. Ceratocystis lukuohia DNA was detected twenty-six times and C. huliohia was detected five times in the PES throughout this study. DNA detections were correlated to frass and wood counts, and the number of felled trees were correlated to wood particle counts but not frass counts. Both the timing and distribution of detections across the sampling grid indicate that tree felling may have reduced airborne detections of Ceratocystis DNA soon after tree felling was completed. A subsequent increase in detections after tree felling ceased may indicate that incomplete removal of infected trees and the appearance of new infections in previously asymptomatic trees could have allowed airborne detections of potentially infectious fungal propagules to once again increase.

Hawaii↗

USGS1994

Lake-level history of Lake Michigan for the past 12,000 years: the record from deep lacustrine sediments

Collection and analysis of an extensive set of seismic-reflection profiles and cores from southern Lake Michigan have provided new data that document the history of the lake basin for the past 12,000 years. Analyses of the seismic data, together with radiocarbon dating, magnetic, sedimentologic, isotopic, and paleontologic studies of core samples, have allowed us to reconstruct lake-level changes during this recent part of the lake's history. The post-glacial history of lake-level changes in the Lake Michigan basin begins about 11.2 ka with the fall from the high Calumet level, caused by the retreat of the Two Rivers glacier, which had blocked the northern outlet of the lake. This lake-level fall was temporarily reversed by a major influx of water from glacial Lake Agassiz (about 10.6 ka), during which deposition of the distinctive gray Wilmette Bed of the Lake Michigan Formation interrupted deposition of red glaciolacustrine sediment. Lake level then continued to fall, culminating in the opening of the North Bay outlet at about 10.3 ka. During the resulting Chippewa low phase, lake level was about 80 m lower than it is today in the southern basin of Lake Michigan. The rise of the early Holocene lake level, controlled primarily by isostatic rebound of the North Bay outlet, resulted in a prominent, planar, transgressive unconformity that eroded most of the shoreline features below present lake level. Superimposed on this overall rise in lake level, a second influx of water from Lake Agassiz temporarily raised lake levels an unknown amount about 9.1 ka. At about 7 ka, lake level may have fallen below the level of the outlet because of sharply drier climate. Sometime between 6 and 5 ka, the character of the lake changed dramatically, probably due mostly to climatic causes, becoming highly undersaturated with respect to calcium carbonate and returning primary control of lake level to the isostatically rising North Bay outlet. Post-Nipissing (about 5 ka) lake level has fallen about 6 m due to erosion of the Port Huron outlet, a trend around which occurred relatively small (± ∼2 m), short-term fluctuations controlled mainly by climatic changes. These cyclic fluctuations are reflected in the sed-imentological and sediment-magnetic properties of the sediments.

Indiana, Illinois, Michigan, Wisconsin↗

USGS2022

Areas contributing recharge to selected production wells in unconfined and confined glacial valley-fill aquifers in Chenango River Basin, New York

In the Chenango River Basin of central New York, unconfined and confined glacial valley-fill aquifers are an important source of drinking-water supplies. The risk of contaminating water withdrawn by wells that tap these aquifers might be reduced if the areas contributing recharge to the wells are delineated and these areas protected from land uses that might affect the water quality. The U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation and the New York State Department of Health, began an investigation in 2019 to improve understanding of groundwater flow and delineate areas contributing recharge to 16 production wells clustered in three study areas in the basin as part of an effort to protect the source of water to these wells. Areas contributing recharge were delineated on the basis of numerical steady-state groundwater-flow models representing long-term average hydrologic conditions. In the Cortland study area, four water suppliers operate 10 production wells that withdraw a total average rate of 2,480 gallons per minute from an unconfined aquifer consisting of well-sorted sand and gravel deposits. Simulated areas contributing recharge to these wells at their average pumping rates covered a total area of 6.93 square miles. Simulated areas contributing recharge extend upgradient from the wells to upland till deposits and to groundwater divides. Some simulated areas contributing recharge include isolated areas remote from the wells. Short simulated groundwater traveltimes from recharging locations to discharging wells indicated that the wells are vulnerable to contamination from land-surface activities; 50 percent of the traveltimes were 10 years or less. Land cover in some of the areas contributing recharge included a substantial amount of urban and agriculture land use. The groundwater-flow model of the Cortland study area was calibrated to available hydrologic data by inverse modeling using nonlinear regression. The parameter variance-covariance matrix from model calibration was used to create parameter sets that reflect the uncertainty of the parameter estimates and the correlation among parameters to evaluate the uncertainty associated with the single, predicted contributing areas to the wells. This analysis led to contributing areas expressed as a probability distribution. Because of the effects of parameter uncertainty, the size of the probabilistic contributing areas was larger than the size of the single, predicted contributing area for the wells. Thus, some areas not in the single, predicted contributing area might actually be in the contributing area, including additional areas of urban and agriculture land use that have the potential to contaminate groundwater. Additional areas that might be in the contributing area included recharge originating near the pumping wells that have relatively short groundwater-flow paths and traveltimes. In each of the Greene and Cincinnatus study areas, one water supplier operates three wells that are screened near the top of the bedrock surface in a confined aquifer consisting of poorly to well-sorted sand and gravel deposits. This confined aquifer is overlain by a lacustrine confining unit of very fine sand, silt, and clay, which in turn is overlain by a thin unconfined aquifer of sand and gravel. The groundwater-flow models for these two areas were manually calibrated because of the limited hydrologic data. Simulated areas contributing recharge to the Greene study area wells covered a total area of 0.35 square mile for the average pumping rate of 170 gallons per minute. The contributing areas extended southeastward of the wells to the groundwater divide in the till uplands. The contributing areas also included remote, isolated areas on the opposite side of the Chenango River from the wells primarily in the till uplands. For the Cincinnatus study area wells, which have a low average pumping rate (34 gallons per minute), the simulated contributing areas totaled 0.06 square mile and were on the same side of the river as the wells, but they are isolated areas remote from the wells primarily in the till-covered bedrock uplands. Land cover in these contributing areas for both study areas is primarily agriculture and forested, with the contributing areas to the Greene study area wells also including some urban land uses. Because the Greene and Cincinnatus study area wells are screened relatively deep and some flow paths to the wells partly travel through the confining unit, which impedes the connection with surface sources of recharge, overall groundwater traveltimes are greater than for wells in the Cortland study area. Fifty percent of Cortland study area wells, but only 9 and 44 percent of Greene and Cincinnatus study area wells, respectively, have groundwater traveltimes of 10 years or less.

New York↗

USGS2011

Summary of November 2010 meeting to evaluate turbidite data for constraining the recurrence parameters of great Cascadia earthquakes for the update of national seismic hazard maps

This report summarizes a meeting of geologists, marine sedimentologists, geophysicists, and seismologists that was held on November 18–19, 2010 at Oregon State University in Corvallis, Oregon. The overall goal of the meeting was to evaluate observations of turbidite deposits to provide constraints on the recurrence time and rupture extent of great Cascadia subduction zone (CSZ) earthquakes for the next update of the U.S. national seismic hazard maps (NSHM). The meeting was convened at Oregon State University because this is the major center for collecting and evaluating turbidite evidence of great Cascadia earthquakes by Chris Goldfinger and his colleagues. We especially wanted the participants to see some of the numerous deep sea cores this group has collected that contain the turbidite deposits. Great earthquakes on the CSZ pose a major tsunami, ground-shaking, and ground-failure hazard to the Pacific Northwest. Figure 1 shows a map of the Pacific Northwest with a model for the rupture zone of a moment magnitude M w 9.0 earthquake on the CSZ and the ground shaking intensity (in ShakeMap format) expected from such an earthquake, based on empirical ground-motion prediction equations. The damaging effects of such an earthquake would occur over a wide swath of the Pacific Northwest and an accompanying tsunami would likely cause devastation along the Pacifc Northwest coast and possibly cause damage and loss of life in other areas of the Pacific. A magnitude 8 earthquake on the CSZ would cause damaging ground shaking and ground failure over a substantial area and could also generate a destructive tsunami. The recent tragic occurrence of the 2011 M w 9.0 Tohoku-Oki, Japan, earthquake highlights the importance of having accurate estimates of the recurrence times and magnitudes of great earthquakes on subduction zones. For the U.S. national seismic hazard maps, estimating the hazard from the Cascadia subduction zone has been based on coastal paleoseismic evidence of great earthquakes over the past 5,000 years. The instrumental catalog of earthquakes is of little use for constraining the hazard of the CSZ, because there are virtually no recorded earthquakes on most of the plate interface of the CSZ. There are no historical accounts in the past 150 years of large earthquakes on most of the CSZ. Until about 20 years ago, some interpreted this lack of recent and historical earthquakes as an indicator that the subduction zone was slipping aseismically and could not produce a great earthquake. The work of Brian Atwater and others, in the late 1980s and the 1990s (Atwater, 1987, 1992; Atwater and others, 1995; Nelson and others, 1996; Clague, 1997; Atwater and Hemphill-Haley, 1997; Atwater and others, 2004) demonstrated that submerged forests, buried soils, tsunami deposits, and liquefaction along and near the coast were compelling evidence of repeated great Cascadia earthquakes over at least the past 5,000 years. Atwater and Hemphill-Haley (1997) concluded from paleoseismic evidence at Willapa Bay, Washington, that great earthquakes ruptured the CSZ with an average recurrence time of about 500 years. The date of the last great CSZ earthquake, January 26, 1700, was established from historical records of the so-called orphan tsunami in Japan that is inferred to have been produced by this earthquake (Satake and others, 1996, 2003; Atwater and others, 2005) and is consistent with tree-ring data from drowned forests in Washington and Oregon. From modeling the observations of the tsunami, Satake and others (2003) estimated a moment magnitude of about 9.0 for this earthquake. Many other paleoseismic sites have been investigated along the Pacific Northwest coast from Vancouver Island to northern California and show evidence of great CSZ earthquakes. Nelson and others (2006) summarized the dates found from these studies and proposed correlations between sites indicating the extent of rupture for individual events. Dating of inferred tsunami deposits in Bradley Lake, Oregon by Kelsey and others (2005), as well as tsunami and subsidence evidence from Six Rivers, Oregon (Kelsey and others, 2002) and Coquille River (Witter and others, 2003), indicates that there were probably M w 8 ruptures in the southern portion of the CSZ in addition to the M w 9 events that rupture the whole length of the CSZ (Nelson and others, 2006). A parallel development over the past 20 years or more is the use of deep-sea turbidite deposits for identifying and dating great Cascadia earthquakes over the past 10,000 years (Adams, 1990; Goldfinger and others, 2003, 2008, in press; Goldfinger, 2011). Turbidites are sediment deposits in the deep ocean from turbidity currents, which are energetic flows of sediment and water along the continental shelf and slope. Adams (1990), using the counts of turbidites in deep-sea cores off the coast of Oregon and Washington collected and analyzed by Griggs (1969) and Griggs and others (1969), proposed that these turbidites were caused by the shaking of great Cascadia earthquakes. Part of his reasoning was that the number (13) of turbidite deposits that occurred since deposition of the Mazama Ash 7,000 years ago gave a recurrence time of about 500 years, consistent with that derived from the coastal submergence data. Adams (1990) also proposed the “confluence test” which evaluates the number of turbidites for submarine channels that form a confluence. He reported that the number of turbidites in the single downstream channel equaled the number in each of the tributary channels. He reasoned that this indicated that the turbidites in each tributary were simultaneously triggered and were, therefore, caused by a common forcing agent. He concluded that shaking from extended ruptures of great Cascadia earthquakes was the most likely cause of these turbidites. Based on the paleoseismic evidence of past great earthquakes, the hazard from the Cascadia subduction zone was included in the 1996 U.S. NSHM (Frankel and others, 1996), which were the basis for seismic provisions in the 2000 International Building Code. These hazard maps used the paleoseismic studies to constrain the recurrence rate of great CSZ earthquakes. Goldfinger and his colleagues have since collected many more deep ocean cores and done extensive analysis on the turbidite deposits that they identified in the cores (Goldfinger and others, 2003, 2008, in press; Goldfinger, 2011). Using their dating of the sediments and correlation of features in the logs of density and magnetic susceptibility between cores, they developed a detailed chronology of great earthquakes along the CSZ for the past 10,000 years (Goldfinger and others, in press). These correlations consist of attempting to match the peaks and valleys in logs of density and magnetic susceptibility between cores separated, in some cases, by hundreds of kilometers. Based on this work, Goldfinger and others (2003, 2008, in press) proposed that the turbidite evidence indicated the occurrence of great earthquakes (M w 8) that only ruptured the southern portion of the CSZ, as well as earthquakes with about M w 9 that ruptured the entire length of the CSZ. For the southernmost portion of the CSZ, Goldfinger and others (in press) proposed a recurrence time of M w 8 or larger earthquakes of about 230 years. This proposed recurrence time was shorter than the 500 year time that was incorporated in one scenario in the NSHM’s. It is important to note that the hazard maps of 1996 and later also included a scenario or set of scenarios with a shorter recurrence time for M w 8 earthquakes, using rupture zones that are distributed along the length of the CSZ (Frankel and others, 1996; Petersen and others, 2008). Originally, this scenario was meant to correspond to the idea that some of the 500-year averaged ruptures seen in the paleoseismic evidence could have been a series of M w 8 earthquakes that occurred over a short period of time (a few decades), rather than M w 9 earthquakes. Figure 2 shows the logic tree for the CSZ used in the 2008 NSHM’s (Petersen and others, 2008). This logic tree includes whole CSZ rupture earthquakes (M w 8.8–9.2) and partial CSZ rupture earthquakes (M w 8.0–8.7). In this latest version of the NSHM’s, the effective recurrence time of earthquakes on the CSZ with moment magnitudes greater than or equal to 8.0 over the various models is about 270 years (Petersen and others, 2008). This recurrence time applies to the entire CSZ, so that the hazard from great earthquakes was approximately equal along the whole zone, although the hazard estimates taper on the northern and southern ends of the CSZ, because of the way rupture zones of M w 8 earthquakes were distributed along the strike of the CSZ. The NSHM will be updated in 2013, as part of the standard update cycle that corresponds to the update cycle of the national model building codes that are based on the seismic hazard maps. A meeting was necessary to assemble a wide group of experts to hear Dr. Goldfinger explain his methodology for dating and correlating the turbidites and for developing the earthquake chronology. The overall goal of the workshop was to evaluate observations of turbidite deposits to provide constraints on the recurrence times and rupture extents of great Cascadia subduction zone earthquakes for the next update of the NSHM. Before the meeting, participants were supplied with the U.S. Geological Survey (USGS) Professional Paper of Goldfinger and others (in press), as well as material from Brian Atwater and Alan Nelson. The agenda of the meeting was developed by Art Frankel, with assistance from Chris Goldfinger, Brian Atwater, Alan Nelson, Mark Petersen, and Craig Weaver. The meeting was hosted by Chris Goldfinger of Oregon State University. We stress that it is difficult to evaluate in a two-day meeting the large amount of work that Goldfinger and his colleagues have done over the past 15 years or more. This meeting is the first step in a process that develops the inputs to the update of the national maps. The conclusions of this workshop will be discussed and possibly modified at the regional Pacific Northwest workshop for the hazard maps to be held in early 2012. Vetting new research results using informed expert opinion is an integral part of updating the national maps and does not reflect on the veracity of these results.

Cascadia↗