Geology topics

Research about Montana

Source-linked reports with geographic coverage including Montana.

At least 271 records · Page 15Linked to original sources

USGS2014

The 3D Elevation Program: summary for Montana

Elevation data are essential to a broad range of applications, including forest resources management, wildlife and habitat management, national security, recreation, and many others. For the State of Montana, elevation data are critical for flood risk management, infrastructure and construction management, agriculture and precision farming, geologic resource assessment and hazard mitigation, natural resources conservation, and other business uses. Today, high-density light detection and ranging (lidar) data are the primary sources for deriving elevation models and other datasets. Federal, State, Tribal, and local agencies work in partnership to (1) replace data that are older and of lower quality and (2) provide coverage where publicly accessible data do not exist. A joint goal of State and Federal partners is to acquire consistent, statewide coverage to support existing and emerging applications enabled by lidar data. The National Enhanced Elevation Assessment evaluated multiple elevation data acquisition options to determine the optimal data quality and data replacement cycle relative to cost to meet the identified requirements of the user community. The evaluation demonstrated that lidar acquisition at quality level 2 for the conterminous United States and quality level 5 ifsar data for Alaska with a 6- to 10-year acquisition cycle provided the highest benefit/cost ratios. The new 3D Elevation Program (3DEP) initiative selected an 8-year acquisition cycle for the respective quality levels. 3DEP, managed by the U.S. Geological Survey (USGS), the Office of Management and Budget Circular A–16 lead agency for terrestrial elevation data, responds to the growing need for high-quality topographic data and a wide range of other 3D representations of the Nation’s natural and constructed features.

Montana↗

USGS2014

Water-quality, bed-sediment, and biological data (October 2011 through September 2012) and statistical summaries of data for streams in the Clark Fork Basin, Montana

Water, bed sediment, and biota were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was conducted by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements associated with historic mining and smelting activities. Sampling sites were located on the Clark Fork and selected tributaries. Water samples were collected periodically at 20 sites from October 2011 through September 2012. Bed-sediment and biota samples were collected once at 13 sites during August 2012. This report presents the analytical results and quality-assurance data for water-quality, bed-sediment, and biota samples collected at sites from October 2011 through September 2012. Water-quality data include concentrations of selected major ions, trace elements, and suspended sediment. Turbidity was analyzed for water samples collected at the four sites where seasonal daily values of turbidity were being determined. Daily values of suspended-sediment concentration and suspended-sediment discharge were determined for four sites. Bed-sediment data include trace-element concentrations in the fine-grained fraction. Biological data include trace-element concentrations in whole-body tissue of aquatic benthic insects. Statistical summaries of water-quality, bed-sediment, and biological data for sites in the upper Clark Fork Basin are provided for the period of record since 1985.

Montana↗

USGS2014

Surficial geologic map of the Red Rock Lakes area, southwest Montana

The Centennial Valley and Centennial Range continue to be formed by ongoing displacement on the Centennial fault. The dominant fault movement is downward, creating space in the valley for lakes and the deposition of sediment. The Centennial Valley originally drained to the northeast through a canyon now represented by a chain of lakes starting with Elk Lake. Subsequently, large landslides blocked and dammed the drainage, which created Lake Centennial, in the Centennial Valley. Sediments deposited in this late Pleistocene lake underlie much of the valley floor and rest on permeable sand and gravel deposited when the valley drained to the northeast. Cold Pleistocene climates enhanced colluvial supply of gravelly sediment to mountain streams and high peak flows carried gravelly sediment into the valley. There, the lower gradient of the streams resulted in deposition of alluvial fans peripheral to Lake Centennial as the lake lowered through time to the level of the two present lakes. Pleistocene glaciers formed in the high Centennial Range, built glacial moraines, and also supplied glacial outwash to the alluvial fans. Winds from the west and south blew sand to the northeast side of the valley building up high dunes. The central part of the map area is flat, sloping to the west by only 0.6 meters in 13 kilometers (2 feet in 8 miles) to form a watery lowland. This lowland contains Upper and Lower Red Rock Lakes, many ponds, and peat lands inside the “water plane,” above which are somewhat steeper slopes. The permeable sands and gravels beneath Lake Centennial sediments provide a path for groundwater recharged from the adjacent uplands. This groundwater leaks upward through Lake Centennial sediments and sustains wetland vegetation into late summer. Upper and Lower Red Rock Lakes are formed by alluvial-fan dams. Alluvial fans converge from both the south and the north to form outlet thresholds that dam the two shallow lakes upstream. The surficial geology aids in understanding how the landscapes in and around the Red Rock Lakes Wildlife Refuge were formed and how they transmit water. This report uses metric units except for altitudes that are also given in feet because contours on the base map are in feet and the reader would have to convert from metric units to feet to understand the map relationships.

Montana↗

USGS2014

Water-quality, bed-sediment, and biological data (October 2012 through September 2013) and statistical summaries of data for streams in the Clark Fork Basin, Montana

Water, bed sediment, and biota were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements associated with historic mining and smelting activities. Sampling sites were located on the Clark Fork and selected tributaries. Water samples were collected periodically at 20 sites from October 2012 through September 2013. Bed-sediment and biota samples were collected once at 13 sites during August 2013. This report presents the analytical results and quality-assurance data for water-quality, bed-sediment, and biota samples collected at sites from October 2012 through September 2013. Water-quality data include concentrations of selected major ions, trace elements, and suspended sediment. Turbidity and dissolved organic carbon were analyzed for water samples collected at the four sites where seasonal daily values of turbidity were being determined. Daily values of mean suspended-sediment concentration and suspended-sediment discharge were determined for four sites. Bed-sediment data include trace-element concentrations in the fine-grained fraction. Biological data include trace-element concentrations in whole-body tissue of aquatic benthic insects. Statistical sum-maries of water-quality, bed-sediment, and biological data for sites in the upper Clark Fork Basin are provided for the period of record.

Montana↗

USGS2014

Water-quality trends for selected sampling sites in the upper Clark Fork Basin, Montana, water years 1996-2010

A large-scale trend analysis was done on specific conductance, selected trace elements (arsenic, cadmium, copper, iron, lead, manganese, and zinc), and suspended-sediment data for 22 sites in the upper Clark Fork Basin for water years 1996–2010. Trend analysis was conducted by using two parametric methods: a time-series model (TSM) and multiple linear regression on time, streamflow, and season (MLR). Trend results for 1996–2010 indicate moderate to large decreases in flow-adjusted concentrations (FACs) and loads of copper (and other metallic elements) and suspended sediment in Silver Bow Creek upstream from Warm Springs. Deposition of metallic elements and suspended sediment within Warm Springs Ponds substantially reduces the downstream transport of those constituents. However, mobilization of copper and suspended sediment from floodplain tailings and stream banks in the Clark Fork reach from Galen to Deer Lodge is a large source of metallic elements and suspended sediment, which also affects downstream transport of those constituents. Copper and suspended-sediment loads mobilized from within this reach accounted for about 40 and 20 percent, respectively, of the loads for Clark Fork at Turah Bridge (site 20); whereas, streamflow contributed from within this reach only accounted for about 8 percent of the streamflow at Turah Bridge. Minor changes in FACs and loads of copper and suspended sediment are indicated for this reach during 1996–2010. Clark Fork reaches downstream from Deer Lodge are relatively smaller sources of metallic elements than the reach from Galen to Deer Lodge. In general, small decreases in loads and FACs of copper and suspended sediment are indicated for Clark Fork sites downstream from Deer Lodge during 1996–2010. Thus, although large decreases in FACs and loads of copper and suspended sediment are indicated for Silver Bow Creek upstream from Warm Springs, those large decreases are not translated to the more downstream reaches largely because of temporal stationarity in constituent transport relations in the Clark Fork reach from Galen to Deer Lodge. Unlike metallic elements, arsenic (a metalloid element) in streams in the upper Clark Fork Basin typically is mostly in dissolved phase, has less variability in concentrations, and has weaker direct relations with suspended-sediment concentrations and streamflow. Arsenic trend results for 1996–2010 indicate generally moderate decreases in FACs and loads in Silver Bow Creek upstream from Opportunity. In general, small temporal changes in loads and FACs of arsenic are indicated for Silver Bow Creek and Clark Fork reaches downstream from Opportunity during 1996–2010. Contribution of arsenic (from Warm Springs Ponds, the Mill-Willow bypass, and groundwater sources) in the Silver Bow Creek reach from Opportunity to Warm Springs is a relatively large source of arsenic. Arsenic loads originating from within this reach accounted for about 11 percent of the load for Clark Fork at Turah Bridge; whereas, streamflow contributed from within this reach only accounted for about 2 percent of the streamflow at Turah Bridge.

Montana↗

USGS2014

Occurrence and hydrogeochemistry of radiochemical constituents in groundwater of Jefferson County and surrounding areas, southwestern Montana, 2007 through 2010

The U.S. Geological Survey, in cooperation with Jefferson County and the Jefferson Valley Conservation District, sampled groundwater in southwestern Montana to evaluate the occurrence and concentration of naturally-occurring radioactive constituents and to identify geologic settings and environmental conditions in which elevated concentrations occur. A total of 168 samples were collected from 128 wells within Broadwater, Deer Lodge, Jefferson, Lewis and Clark, Madison, Powell, and Silver Bow Counties from 2007 through 2010. Most wells were used for domestic purposes and were primary sources of drinking water for individual households. Water-quality samples were collected from wells completed within six generalized geologic units, and analyzed for constituents including uranium, radon, gross alpha-particle activity, and gross beta-particle activity. Thirty-eight wells with elevated concentrations or activities were sampled a second time to examine variability in water quality throughout time. These water-quality samples were analyzed for an expanded list of radioactive constituents including the following: three isotopes of uranium (uranium-234, uranium-235, and uranium-238), three isotopes of radium (radium-224, radium-226, and radium-228), and polonium-210. Existing U.S. Geological Survey and Montana Bureau of Mines and Geology uranium and radon water-quality data collected as part of other investigations through 2011 from wells within the study area were compiled as part of this investigation. Water-quality data from this study were compared to data collected nationwide by the U.S. Geological Survey through 2011. Radionuclide samples for this study typically were analyzed within a few days after collection, and therefore data for this study may closely represent the concentrations and activities of water being consumed locally from domestic wells. Radioactive constituents were detected in water from every well sampled during this study regardless of location or geologic unit. Nearly 41 percent of sampled wells had at least one radioactive constituent concentration that exceeded U.S. Environmental Protection Agency drinking-water standards or screening levels. Uranium concentrations were higher than the U.S. Environmental Protection Agency maximum contaminant level (MCL) of 30 micrograms per liter in samples from 14 percent of the wells. Radon concentrations exceeded a proposed MCL of 4,000 picocuries per liter in 27 percent of the wells. Combined radium (radium-226 and radium-228) exceeded the MCL of 5 picocuries per liter in samples from 10 of 47 wells. About 40 percent (42 of 104 wells) of the wells had gross alpha-particle activities (72-hour count) at or greater than a screening level of 15 pCi/L. Gross beta-particle activity exceeded the U.S. Environmental Protection Agency 50 picocuries per liter screening level in samples from 5 of 104 wells. Maximum radium-224 and polonium-210 activities in study wells were 16.1 and 3.08 picocuries per liter, respectively; these isotopes are constituents of human-health concern, but the U.S. Environmental Protection Agency has not established MCLs for them. Radioactive constituent concentrations or activities exceeded at least one established drinking-water standard, proposed drinking-water standard, or screening level in groundwater samples from five of six generalized geologic units assessed during this study. Radioactive constituent concentrations or activities were variable not only within each geologic unit, but also among wells that were completed in the same geologic unit and in close proximity to one another. Established or proposed drinking-water standards were exceeded most frequently in water from wells completed in the generalized geologic unit that includes rocks of the Boulder batholith and other Tertiary through Cretaceous igneous intrusive rocks (commonly described as granite). Specifically, of the wells completed in the Boulder batholith and related rocks sampled as part of this study, 24 percent exceeded the MCL of 30 micrograms per liter for uranium, 50 percent exceeded the proposed alternative MCL of 4,000 picocuries per liter for radon, and 27 percent exceeded the MCL of 5 micrograms per liter for combined radium-226 and radium-228. Elevated radioactive constituent values were detected in samples representing a large range of field properties and water types. Correlations between radioactive constituents and pH, dissolved oxygen, and most major ions were not statistically significant (p-value > 0.05) or were weakly correlated with Spearman correlation coefficients (rho) ranging from -0.5 to 0.5. Moderate correlations did exist between gross beta-particle activity and potassium (rho = 0.72 to 0.82), likely because one potassium isotope (potassium-40) is a beta-particle emitter. Total dissolved solids and specific conductance also were moderately correlated (rho = 0.62 to 0.71) with gross alpha-particle and gross beta-particle activity, indicating that higher radioactivity values can be associated with higher total dissolved solids. Correlations were evaluated among radioactive constituents. Moderate to strong correlations occurred between gross alpha-particle and beta-particle activities (rho = 0.77 to 0.96) and radium isotopes (rho = 0.78 to 0.92). Correlations between gross alpha-particle activity (72-hour count) and all analyzed radioactive constituents were statistically significant (p-value < 0.05), and therefore, gross alpha-particle activity likely may be used as a screening tool for determining the presence of radionuclides in area waters. In this study, gross alpha-particle activities of 7 picocuries per liter or greater were associated with all radioactive constituents whose concentrations exceeded drinking-water standards or screening levels. Radiochemical results varied temporally in samples from several of the thirty-eight wells sampled at least twice during the study. The time between successive sampling events ranged from about 1 to 10 months for 29 wells to about 3 years for the other 9 wells. Radiochemical constituents that varied by greater than 30 percent between sampling events included uranium (29 percent of the resampled wells), and radon (11 percent of the resampled wells), gross alpha-particle activity (38 percent of the resampled wells), and gross beta-particle activity (15 percent of the resampled wells). Variability in uranium concentrations from two wells was sufficiently large that concentrations were less than the MCL in the first set of samples and greater than the MCL in the second. Sample holding times affect analytical results in this study. Gross alpha-particle and gross beta-particle activities were measured twice, 72 hours and 30 days after sample collection. Gross alpha-particle activity decreased an average of 37 percent between measurements, indicating the presence of short-lived alpha-emitting radionuclides in these samples. Gross beta-particle activity increased an average of 31 percent between measurements, indicating ingrowth of longer-lived beta-emitting radionuclides.

Montana↗

USGS2014

Delineation of brine contamination in and near the East Poplar oil field, Fort Peck Indian Reservation, northeastern Montana, 2004-09

The extent of brine contamination in the shallow aquifers in and near the East Poplar oil field is as much as 17.9 square miles and appears to be present throughout the entire saturated zone in contaminated areas. The brine contamination affects 15–37 billion gallons of groundwater. Brine contamination in the shallow aquifers east of the Poplar River generally moves to the southwest toward the river and then southward in the Poplar River valley. The likely source of brine contamination in the shallow aquifers is brine that is produced with crude oil in the East Poplar oil field study area. Brine contamination has not only affected the water quality from privately owned wells in and near the East Poplar oil field, but also the city of Poplar’s public water-supply wells. Three water-quality types characterize water in the shallow aquifers; a fourth water-quality type in the study area characterizes the brine. Type 1 is uncontaminated water that is suitable for most domestic purposes and typically contains sodium bicarbonate and sodium/magnesium sulfate as the dominant ions. Type 2 is moderately contaminated water that is suitable for some domestic purposes, but not used for drinking water, and typically contains sodium and chloride as the dominant ions. Type 3 is considerably contaminated water that is unsuitable for any domestic purpose and always contains sodium and chloride as the dominant ions. Type 3 quality of water in the shallow aquifers is similar to Type 4, which is the brine that is produced with crude oil. Electromagnetic apparent conductivity data were collected in the 106 square-mile area and used to determine extent of brine contamination. These data were collected and interpreted in conjunction with water-quality data collected through 2009 to delineate brine plumes in the shallow aquifers. Monitoring wells subsequently were drilled in some areas without existing water wells to confirm most of the delineated brine plumes; however, several possible plumes do not contain either existing water wells or monitoring wells. Analysis of groundwater samples from wells confirms the presence of 12.1 square miles of contamination, as much as 1.7 square miles of which is considerably contaminated (Type 3). Electromagnetic apparent conductivity data in areas with no wells delineate an additional 5.8 square miles of possible contamination, 2.1 square miles of which might be considerably contaminated (Type 3). Storage-tank facilities, oil wells, brine-injection wells, pipelines, and pits are likely sources of brine in the study area. It is not possible to identify discrete oil-related features as likely sources of brine plumes because several features commonly are co-located. During the latter half of the twentieth century, many brine plumes migrated beyond the immediate source area and likely mix together in modern and ancestral Poplar River valley subareas.

Montana↗

USGS2014

A precipitation-runoff model for simulating natural streamflow conditions in the Smith River watershed, Montana, water years 1996-2008

This report documents the construction of a precipitation-runoff model for simulating natural streamflow in the Smith River watershed, Montana. This Precipitation-Runoff Modeling System model, constructed in cooperation with the Meagher County Conservation District, can be used to examine the general hydrologic framework of the Smith River watershed, including quantification of precipitation, evapotranspiration, and streamflow; partitioning of streamflow between surface runoff and subsurface flow; and quantifying contributions to streamflow from several parts of the watershed. The model was constructed by using spatial datasets describing watershed topography, the streams, and the hydrologic characteristics of the basin soils and vegetation. Time-series data (daily total precipitation, and daily minimum and maximum temperature) were input to the model to simulate daily streamflow. The model was calibrated for water years 2002–2007 and evaluated for water years 1996–2001. Though water year 2008 was included in the study period to evaluate water-budget components, calibration and evaluation data were unavailable for that year. During the calibration and evaluation periods, simulated-natural flow values were compared to reconstructed-natural streamflow data. These reconstructed-natural streamflow data were calculated by adding Bureau of Reclamation’s depletions data to the observed streamflows. Reconstructed-natural streamflows represent estimates of streamflows for water years 1996–2007 assuming there was no agricultural water-resources development in the watershed. Additional calibration targets were basin mean monthly solar radiation and potential evapotranspiration. The model estimated the hydrologic processes in the Smith River watershed during the calibration and evaluation periods. Simulated-natural mean annual and mean monthly flows generally were the same or higher than the reconstructed-natural streamflow values during the calibration period, whereas they were lower during the evaluation period. The shape of the annual hydrographs for the simulated-natural daily streamflow values matched the shape of the hydrographs for the reconstructed-natural values for most of the calibration period, but daily streamflow values were underestimated during the evaluation period for water years 1996–1998. The model enabled a detailed evaluation of the components of the water budget within the Smith River watershed during the water year 1996–2008 study period. During this study period, simulated mean annual precipitation across the Smith River watershed was 16 inches, out of which 14 inches evaporated or transpired and 2 inches left the basin as streamflow. Per the precipitation-runoff model simulations, during most of the year, surface runoff rarely (less than 2 percent of the time during water years 2002–2008) makes up more than 10 percent of the total streamflow. Subsurface flow (the combination of interflow and groundwater flow) makes up most of the total streamflow (99 or more percent of total streamflow for 71 percent of the time during water years 2002–2008).

Montana↗

USGS2014

A geologic and mineral exploration spatial database for the Stillwater Complex, Montana

The Stillwater Complex is a Neoarchean, ultramafic to mafic layered intrusion exposed in the Beartooth Mountains in south-central Montana. This igneous intrusion contains magmatic mineralization that is variably enriched in strategic and critical commodities such as chromium, nickel, and the platinum-group elements. One deposit, the J-M Reef, is the sole source of primary production and reserves for platinum-group elements in the United States. A large amount of information has been collected on the Stillwater Complex. In the 1930s, academics, the U.S. Geological Survey, and the [U.S.] Bureau of Mines initiated geologic investigations on the Stillwater Complex. Since that time, more than 600 publications on the Stillwater Complex have appeared in the scientific literature. Exploration and mining companies have collected even more information since the 1920s. This report provides essential spatially referenced datasets based on geologic mapping and mineral exploration activities conducted from the 1920s to the 1990s. This information will facilitate research on the complex and provide background material needed to explore for mineral resources and to develop sound land-management policy.

Montana↗

USGS2014

Quantifying the effectiveness of conservation measures to control the spread of anthropogenic hybridization in stream salmonids: A climate adaptation case study

Quantifying the effectiveness of management actions to mitigate the effects of changing climatic conditions (i.e., climate adaptation) can be difficult, yet critical for conservation. We used population genetic data from 1984 to 2011 to assess the degree to which ambient climatic conditions and targeted suppression of sources of nonnative Rainbow Trout Oncorhynchus mykiss have influenced the spread of introgressive hybridization in native populations of Westslope Cutthroat Trout O. clarkii lewisi . We found rapid expansion in the spatial distribution and proportion of nonnative genetic admixture in hybridized populations from 1984 to 2004, but minimal change since 2004. The spread of hybridization was negatively correlated with the number of streamflow events in May that exceeded the 75th percentile of historic flows ( r = −0.98) and positively correlated with August stream temperatures ( r = 0.89). Concomitantly, suppression data showed a 60% decline in catch per unit effort for fish with a high proportion of Rainbow Trout admixture, rendering some uncertainty as to the relative strength of factors controlling the spread of hybridization. Our results illustrate the importance of initiating management actions to mitigate the potential effects of climate change, even where data describing the effectiveness of such actions are initially limited but the risks are severe.

Montana↗

USGS2014

Simulating future residential property losses from wildfire in Flathead County, Montana

Wildfire damages to private residences in the United States and elsewhere have increased as a result of expansion of the wildland-urban interface (WUI) and other factors. Understanding this unwelcome trend requires analytical frameworks that simulate how various interacting social, economic, and biophysical factors influence those damages. A methodological framework is developed for simulating expected residential property losses from wildfire [E(RLW)], which is a probabilistic monetary measure of wildfire risk to residential properties in the WUI. E(RLW) is simulated for Flathead County, Montana for five, 10-year subperiods covering the period 2010-2059, under various assumptions about future climate change, economic growth, land use policy, and forest management. Results show statistically significant increases in the spatial extent of WUI properties, the number of residential structures at risk from wildfire, and E(RLW) over the 50-year evaluation period for both the county and smaller subareas (i.e., neighborhoods and parcels). The E(RLW) simulation framework presented here advances the field of wildfire risk assessment by providing a finer-scale tool that incorporates a set of dynamic, interacting processes. The framework can be applied using other scenarios for climate change, economic growth, land use policy, and forest management, and in other areas.

Montana↗

USGS2014

Assessing the importance of terrain parameters on glide avalanche release

Glide snow avalanches are dangerous and difficult to predict. Despite recent research there is still a lack of understanding regarding the controls of glide avalanche release. Glide avalanches often occur in similar terrain or the same locations annually and observations suggest that topography may be critical. Thus, to gain an understanding of the terrain component of these types of avalanches we examined terrain parameters associated with glide avalanche release as well as areas of consistent glide crack formation but no subsequent avalanches. Glide avalanche occurrences visible from the Going-to-the-Sun Road corridor in Glacier National Park, Montana from 2003-2013 were investigated using an avalanche database derived of daily observations each year from April 1 to June 15. This yielded 192 glide avalanches in 53 distinct avalanche paths. Each avalanche occurrence was digitized in a GIS using satellite, oblique, and aerial imagery as reference. Topographical parameters such as area, slope, aspect, elevation and elevation were then derived for the entire dataset utilizing GIS tools and a 10m DEM. Land surface substrate and surface geology were derived from National Park Service Inventory and Monitoring maps and U.S. Geological Survey surface geology maps, respectively. Surface roughness and glide factor were calculated using a four level classification index. . Then, each avalanche occurrence was aggregated to general avalanche release zones and the frequencies were compared. For this study, glide avalanches released in elevations ranging from 1300 to 2700 m with a mean aspect of 98 degrees (east) and a mean slope angle of 38 degrees. The mean profile curvature for all glide avalanches was 0.15 and a plan curvature of -0.01, suggesting a fairly linear surface (i.e. neither convex nor concave). The glide avalanches occurred in mostly bedrock made up of dolomite and limestone slabs and talus deposits with very few occurring in alpine meadows. However, not all glide avalanches failed as cohesive slabs on this bedrock surface. Consequently, surface roughness proved to be a useful descriptive variable to discriminate between slopes that avalanched and those that did not. Annual 'repeat offender' glide avalanche paths were characterized by smooth outcropping rock plates with stratification planes parallel to the slope. Combined with aspect these repeat offenders were also members of the highest glide category. Using this understanding of the role of topographic parameters on glide avalanche activity, a spatial terrain based model was developed to identify other areas with high glide avalanche potential outside of our immediate observation area.

Montana↗

USGS2013

Black bear density in Glacier National Park, Montana

We report the first abundance and density estimates for American black bears ( Ursus americanus ) in Glacier National Park (NP),Montana, USA.We used data from 2 independent and concurrent noninvasive genetic sampling methods—hair traps and bear rubs—collected during 2004 to generate individual black bear encounter histories for use in closed population mark–recapture models. We improved the precision of our abundance estimate by using noninvasive genetic detection events to develop individual-level covariates of sampling effort within the full and one-half mean maximum distance moved (MMDM) from each bear’s estimated activity center to explain capture probability heterogeneity and inform our estimate of the effective sampling area.Models including the one-halfMMDMcovariate received overwhelming Akaike’s Information Criterion support suggesting that buffering our study area by this distance would be more appropriate than no buffer or the full MMDM buffer for estimating the effectively sampled area and thereby density. Our modelaveraged super-population abundance estimate was 603 (95% CI¼522–684) black bears for Glacier NP. Our black bear density estimate (11.4 bears/100 km2, 95% CI¼9.9–13.0) was consistent with published estimates for populations that are sympatric with grizzly bears (U. arctos) and without access to spawning salmonids. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Montana↗

USGS2013

Spawning related movement of shovelnose sturgeon in the Missouri River above Fort Peck Reservoir, Montana

The hypotheses of this study were (i) that shovelnose sturgeon would make upstream movements to spawn, (ii) movement of spawning fish would be greater in a year with higher discharge, and (iii) that spawning fish would have greater movements than reproductively inactive fish. Shovelnose sturgeon Scaphirhynchus platorynchus (Rafinesque, 1820) in five reproductive categories (e.g. males, confirmed spawning females, potentially spawning females, atretic females, and reproductively inactive females) were tracked in 2008 and 2009. All reproductive categories, except reproductively inactive females, exhibited large-scale movements and had omnidirectional movements. No differences in movement rates were observed in confirmed spawning females between years despite a 45% higher peak discharge in 2008 (839 m 3 s −1 ) than in 2009 (578 m 3 s −1 ). A peak discharge was obtained at a faster rate in 2008 (165 m 3 s −1 day −1 ) than in 2009 (39 m 3 s −1 day −1 ), and high discharge was of greater duration in 2008. Reproductively inactive females did not exhibit large-scale movements and their movement rate differed from other reproductive categories. Shovelnose sturgeon spawned in both years, despite highly varying hydrographs between years.

Montana↗

USGS2013

Comparison of harvest scenarios for the cost-effective suppression of Lake Trout in Swan Lake, Montana

Given the large amount of resources required for long-term control or eradication projects, it is important to assess strategies and associated costs and outcomes before a particular plan is implemented. We developed a population model to assess the cost-effectiveness of mechanical removal strategies for suppressing long-term abundance of nonnative Lake Trout Salvelinus namaycush in Swan Lake, Montana. We examined the efficacy of targeting life stages (i.e., juveniles or adults) using temporally pulsed fishing effort for reducing abundance and program cost. Exploitation rates were high (0.80 for juveniles and 0.68 for adults) compared with other lakes in the western USA with Lake Trout suppression programs. Harvesting juveniles every year caused the population to decline, whereas harvesting only adults caused the population to increase above carrying capacity. Simultaneous harvest of juveniles and adults was required to cause the population to collapse (i.e., 95% reduction relative to unharvested abundance) with 95% confidence. The population could collapse within 15 years for a total program cost of US$1,578,480 using the most aggressive scenario. Substantial variation in cost existed among harvest scenarios for a given reduction in abundance; however, total program cost was minimized when collapse was rapid. Our approach provides a useful case study for evaluating long-term mechanical removal options for fish populations that are not likely to be eradicated.

Montana↗

USGS2013

Spatial contexts for temporal variability in alpine vegetation under ongoing climate change

A framework to monitor mountain summit vegetation (The Global Observation Research Initiative in Alpine Environments, GLORIA) was initiated in 1997. GLORIA results should be taken within a regional context of the spatial variability of alpine tundra. Changes observed at GLORIA sites in Glacier National Park, Montana, USA are quantified within the context of the range of variability observed in alpine tundra across much of western North America. Dissimilarity is calculated and used in nonmetric multidimensional scaling for repeated measures of vascular species cover at 14 GLORIA sites with 525 nearby sites and with 436 sites in western North America. The lengths of the trajectories of the GLORIA sites in ordination space are compared to the dimensions of the space created by the larger datasets. The absolute amount of change on the GLORIA summits over 5 years is high, but the degree of change is small relative to the geographical context. The GLORIA sites are on the margin of the ordination volumes with the large datasets. The GLORIA summit vegetation appears to be specialized, arguing for the intrinsic value of early observed change in limited niche space.

Montana↗

USGS2013

Incorporating probabilistic seasonal climate forecasts into river management using a risk-based framework

[1] Despite the influence of hydroclimate on river ecosystems, most efforts to date have focused on using climate information to predict streamflow for water supply. However, as water demands intensify and river systems are increasingly stressed, research is needed to explicitly integrate climate into streamflow forecasts that are relevant to river ecosystem management. To this end, we present a five step risk-based framework: (1) define risk tolerance, (2) develop a streamflow forecast model, (3) generate climate forecast ensembles, (4) estimate streamflow ensembles and associated risk, and (5) manage for climate risk. The framework is successfully demonstrated for an unregulated watershed in southwest Montana, where the combination of recent drought and water withdrawals has made it challenging to maintain flows needed for healthy fisheries. We put forth a generalized linear modeling (GLM) approach to develop a suite of tools that skillfully model decision-relevant low flow characteristics in terms of climate predictors. Probabilistic precipitation forecasts are used in conjunction with the GLMs, resulting in season-ahead prediction ensembles that provide the full risk profile. These tools are embedded in an end-to-end risk management framework that directly supports proactive fish conservation efforts. Results show that the use of forecasts can be beneficial to planning, especially in wet years, but historical precipitation forecasts are quite conservative (i.e., not very “sharp”). Synthetic forecasts show that a modest “sharpening” can strongly impact risk and improve skill. We emphasize that use in management depends on defining relevant environmental flows and risk tolerance, requiring local stakeholder involvement.

Montana↗

USGS2013

Juvenile movement among different populations of cutthroat trout introduced as embryos to vacant habitat

Translocations are frequently used to increase the abundance and range of endangered fishes. One factor likely to affect the outcome of translocations is fish movement. We introduced embryos from five Westslope Cutthroat Trout Oncorhynchus clarkii lewisi populations (both hatchery and wild) at five different locations within a fishless watershed. We then examined the movement of age‐1 and age‐2 fish and looked for differences in movement distance among source populations and among introduction sites; we also examined the interactions among age, population, and introduction site. At age 1, most individuals (90.9%) remained within 1,000 m their introduction sites. By age 2, the majority of individuals (58.3%) still remained within 1,000 m of their introduction site, but considerably more individuals had moved downstream, some more than 6,000 m from their introduction site. We observed a significant interaction between age and source population ( F 4, 1077 = 15.45, P < 0.0001) as well as between age and introduction site ( F 41, 1077 = 11.39, P < 0.0008), so we presented results in the context of these interactions. Within age‐groups, we observed differences in movement behavior among source populations and among donor populations of Westslope Cutthroat Trout. We discuss these findings in light of previous research on juvenile salmonid movement.

Montana↗