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Research about Idaho

Source-linked reports with geographic coverage including Idaho.

At least 433 records · Page 24Linked to original sources
USGS2007

Water-resource trends and comparisons between partial-development and October 2006 hydrologic conditions, Wood River Valley, south-central Idaho

This report analyzes trends in ground-water and surface-water data, documents 2006 hydrologic conditions, and compares 2006 and historic ground-water data of the Wood River Valley of south-central Idaho. The Wood River Valley extends from Galena Summit southward to the Timmerman Hills. It is comprised of a single unconfined aquifer and an underlying confined aquifer present south of Baseline Road in the southern part of the study area. Streams are well-connected to the shallow unconfined aquifer. Because the entire population of the area depends on ground water for domestic supply, either from domestic or municipal-supply wells, rapid population growth since the 1970s has raised concerns about the continued availability of ground and surface water to support existing uses and streamflow. To help address these concerns, this report evaluates ground- and surface-water conditions in the area before and during the population growth that started in the 1970s. Mean annual water levels in three wells (two completed in the unconfined aquifer and one in the confined aquifer) with more than 50 years of semi-annual measurements showed statistically significant declining trends. Mean annual and monthly streamflow trends were analyzed for three gaging stations in the Wood River Valley. The Big Wood River at Hailey gaging station (13139500) showed a statistically significant trend of a 25-percent increase in mean monthly base flow for March over the 90-year period of record, possibly because of earlier snowpack runoff. Both the 7-day and 30-day low-flow analyses for the Big Wood River near Bellevue gaging station (13141000) show a mean decrease of approximately 15 cubic feet per second since the 1940s, and mean monthly discharge showed statistically significant decreasing trends for December, January, and February. The Silver Creek at Sportsman Access near Picabo gaging station (13150430) also showed statistically significant decreasing trends in annual and mean monthly discharge for July through February and April from 1975 to 2005. Comparisons of partial-development (ground-water conditions from 1952 to 1986) and 2006 ground-water resources in the Wood River Valley using a geographic information system indicate that most ground-water levels for the unconfined aquifer in the study area are either stable or declining. Declines are predominant in the southern part of the study area south of Hailey, and some areas exceed what is expected of natural fluctuations in ground-water levels. Some ground-water levels rose in the northern part of the study area; however, these increases are approximated due to a lack of water-level data in the area. Ground-water level declines in the confined aquifer exceed the range of expected natural fluctuations in large areas of the confined aquifer in the southern part of the study area in the Bellevue fan. However, the results in this area are approximated due to limited available water-level data.

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USGS2006

Effect of mining and related activities on the sediment trace element geochemistry of Lake Coeur D'Alene, Idaho, USA. Part I: Surface sediments

During the summer of 1989 surface sediment samples were collected in Lake Coeur d'Alene, the Coeur d'Alene River and the St Joe River, Idaho, at a density of approximately one sample per square kilometre. Additional samples were collected from the banks of the South Fork of the Coeur d'Alene and the Coeur d'Alene Rivers in 1991. All the samples were collected to determine trace element concentrations, partitioning and distribution patterns, and to relate them to mining, mining related and discharge operations that have occurred in the Coeur d'Alene district since the 1880s, some of which are ongoing. Most of the surface sediments in Lake Coeur d'Alene north of Conkling Point and Carey Bay are substantially enriched in Ag, As, Cu, Cd, Hg, Pb, Sb and Zn relative to unaffected sediments in the southern portion of the lake near the St Joe River. All the trace element enriched sediments are extremely fine grained (mean grain sizes « 63 μm). Most of the enriched trace elements, based on both the chemical analyses of separated heavy and light mineral fractions and a two step sequential extraction procedure, are associated with an operationally defined Fe oxide phase; much smaller percentages are associated either with operationally defined organics/sulphides or refractory phases. The presence, concentration and distribution of the Fe oxides and heavy minerals indicates that a substantial portion of the enriched trace elements are probably coming from the Coeur d'Alene River, which is serving as a point source. Within the lake, this relatively simple point source pattern is complicated by a combination of (1) the formation of trace element rich authigenic Fe oxides that appear to have reprecipitated from material solubilized from anoxic bed sediments and (2) physical remobilization by currents and wind driven waves. The processes that have caused the trace element enrichment in the surface sediments of Lake Coeur d'Alene are likely to continue for the foreseeable future.

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USGS2006

Microsatellite variation reveals weak genetic structure and retention of genetic variability in threatened Chinook salmon (Oncorhynchus tshawytscha) within a Snake River watershed

Pacific salmon ( Oncorhynchus spp.) have been central to the development of management concepts associated with evolutionarily significant units (ESUs), yet there are still relatively few studies of genetic diversity within threatened and endangered ESUs for salmon or other species. We analyzed genetic variation at 10 microsatellite loci to evaluate spatial population structure and genetic variability in indigenous Chinook salmon ( Oncorhynchus tshawytscha ) across a large wilderness basin within a Snake River ESU. Despite dramatic 20th century declines in abundance, these populations retained robust levels of genetic variability. No significant genetic bottlenecks were found, although the bottleneck metric (M ratio) was significantly correlated with average population size and variability. Weak but significant genetic structure existed among tributaries despite evidence of high levels of gene flow, with the strongest genetic differentiation mirroring the physical segregation of fish from two sub-basins. Despite the more recent colonization of one sub-basin and differences between sub-basins in the natural level of fragmentation, gene diversity and genetic differentiation were similar between sub-basins. Various factors, such as the (unknown) genetic contribution of precocial males, genetic compensation, lack of hatchery influence, and high levels of current gene flow may have contributed to the persistence of genetic variability in this system in spite of historical declines. This unique study of indigenous Chinook salmon underscores the importance of maintaining natural populations in interconnected and complex habitats to minimize losses of genetic diversity within ESUs.

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USGS2006

Effects of radiomarking on prairie falcons: Attachment failures provide insights about survival

From 1999–2002, we attached satellite-received platform transmitter terminals (PTTs) to 40 adult female prairie falcons ( Falco mexicanus ) on their nesting grounds in the Snake River Birds of Prey National Conservation Area (NCA) in southwest Idaho. We used 3 variations of a backpack harness design that had been used previously on raptors. Each radiomarked falcon also received a color leg band with a unique alphanumeric code. We monitored survival of birds using radiotelemetry and searched for marked birds on their nesting grounds during breeding seasons after marking. Because 6 falcons removed their harnesses during the first year, we were able to compare survival rates of birds that shed PTTs with those that retained them. We describe a harness design that failed prematurely as well as designs that proved successful for long-term PTT attachment. We resighted 21 marked individuals on nesting areas 1–5 years after they were radiomarked and documented 13 mortalities of satellite-tracked falcons. We used a Cormack-Jolly-Seber model to estimate apparent survival probability based on band resighting and telemetry data. Platform transmitter terminals had no short-term effects on falcons or their nesting success during the nesting season they were marked, but birds that shed their transmitters increased their probability of survival. Estimated annual survival for birds that shed their transmitters was 87% compared to 49% for birds wearing transmitters. We discuss possible reasons for differences in apparent survival rates and offer recommendations for future marking of falcons.

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USGS2006

Interactive effects of dissolved zinc and orthophosphate on phytoplankton from Coeur d'Alene Lake, Idaho

Within the longitudinal chemical-concentration gradient in Coeur d'Alene Lake, generated by inputs from the St. Joe and Coeur d'Alene Rivers, two dominant algal species, Chlorella minutissima and Asterionella formosa, were isolated and cultured in chemically defined media to examine growth response to a range of dissolved orthophosphate concentrations and zinc-ion activities representative of the region within- and up-gradient of the Coeur d'Alene River inlet to the lake. Although zinc is an essential micronutrient, the toxicity of algal species to elevated concentrations of uncomplexed zinc has been demonstrated, and affects the metabolism of phosphorus (Kuwabara, 1985a; Kuwabara and others, 1986), the limiting nutrient in the lake. This interaction between solutes could be of management interest. As an extension of field work conducted in August, 1999 (Kuwabara and others, 2003b), the water column and benthos of Coeur d'Alene Lake were sampled in August 2001, June 2004 and June 2005 (Fig. 1; Table 1) to provide the biological characterization in terms of phytoplankton community composition, benthic macroinvertebrate community composition and benthic chlorophyll concentrations, as well as chemical characterizations at six sites (three depths per site) within the lake. This work, in support of the Idaho Department of Environmental Quality and regional tribal organizations, provides the first phytoplankton response models in a format that may be incorporated into a process-interdependent water-quality model like CAEDYM (Fig. 2; Brookes and others, 2004; Centre for Water Research, 2006) as a management tool for the lake. This study provides information in support of developing process-interdependent solute-transport models for the watershed (that is, models integrating physical, geochemical and biological processes), and hence in support of subsequent evaluation of remediation or load-allocation strategies. The following two questions are posed: Are dissolved zinc and orthophosphate concentrations interactively associated with growth parameters of dominant phytoplankton species within the longitudinal concentration gradient of Coeur d'Alene Lake? If so, can these interactions be quantitatively incorporated into a water-quality model for the lake?

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USGS2006

Instream flow characterization of Upper Salmon River basin streams, central Idaho, 2005

Anadromous fish populations in the Columbia River Basin have plummeted in the last 100 years. This severe decline led to Federal listing of Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss) stocks as endangered or threatened under the Endangered Species Act (ESA) in the 1990s. Historically, the upper Salmon River Basin (upstream of the confluence with the Pahsimeroi River) in Idaho provided migration corridors and significant habitat for these ESA-listed species, in addition to the ESA-listed bull trout (Salvelinus confluentus). Human development has modified the original streamflow conditions in many streams in the upper Salmon River Basin. Summer streamflow modifications resulting from irrigation practices, have directly affected quantity and quality of fish habitat and also have affected migration and (or) access to suitable spawning and rearing habitat for these fish. As a result of these ESA listings and Action 149 of the Federal Columbia River Power System Biological Opinion of 2000, the Bureau of Reclamation was tasked to conduct streamflow characterization studies in the upper Salmon River Basin to clearly define habitat requirements for effective species management and habitat restoration. These studies include collection of habitat and streamflow information for the Physical Habitat Simulation System (PHABSIM) model, a widely applied method to determine relations between habitat and discharge requirements for various fish species and life stages. Model simulation results can be used by resource managers to guide habitat restoration efforts by evaluating potential fish habitat and passage improvements by increasing or decreasing streamflow. In 2005, instream flow characterization studies were completed on Big Boulder, Challis, Bear, Mill, and Morgan Creeks. Continuous streamflow data were recorded upstream of all diversions on Big Boulder. Instantaneous measurements of discharge were also made at selected sites. In addition, natural summer streamflows were estimated for each study site using regional regression equations. This report describes PHABSIM modeling results for bull trout, Chinook salmon, and steelhead trout during summer streamflows. Habitat/discharge relations were summarized for adult and spawning life stages at each study site. In addition, streamflow needs for riffle dwelling invertebrate taxa (Ephemeroptera, Plecoptera, and Trichoptera) are presented. Adult fish passage and discharge relations were evaluated at specific transects that were identified as potential low-streamflow passage barriers at each study site. Continuous summer water temperature data for selected study sites were summarized and compared with Idaho Water Quality Standards and various water temperature requirements of targeted fish species. Results of these habitat studies can be used to prioritize and direct cost-effective actions to improve fish habitat for ESA-listed anadromous and native fish species in the basin. These actions may include acquiring water during critical low-flow periods by leasing or modifying irrigation delivery systems to minimize out-of-stream diversions.

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USGS2005

Validation of abundance estimates from mark–recapture and removal techniques for rainbow trout captured by electrofishing in small streams

Estimation of fish abundance in streams using the removal model or the Lincoln - Peterson mark - recapture model is a common practice in fisheries. These models produce misleading results if their assumptions are violated. We evaluated the assumptions of these two models via electrofishing of rainbow trout Oncorhynchus mykiss in central Idaho streams. For one-, two-, three-, and four-pass sampling effort in closed sites, we evaluated the influences of fish size and habitat characteristics on sampling efficiency and the accuracy of removal abundance estimates. We also examined the use of models to generate unbiased estimates of fish abundance through adjustment of total catch or biased removal estimates. Our results suggested that the assumptions of the mark - recapture model were satisfied and that abundance estimates based on this approach were unbiased. In contrast, the removal model assumptions were not met. Decreasing sampling efficiencies over removal passes resulted in underestimated population sizes and overestimates of sampling efficiency. This bias decreased, but was not eliminated, with increased sampling effort. Biased removal estimates based on different levels of effort were highly correlated with each other but were less correlated with unbiased mark - recapture estimates. Stream size decreased sampling efficiency, and stream size and instream wood increased the negative bias of removal estimates. We found that reliable estimates of population abundance could be obtained from models of sampling efficiency for different levels of effort. Validation of abundance estimates requires extra attention to routine sampling considerations but can help fisheries biologists avoid pitfalls associated with biased data and facilitate standardized comparisons among studies that employ different sampling methods.

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USGS2005

Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications

Between 1952 and 1984, low-level radioactive waste was introduced directly into the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho. These wastes were generated, principally, at the nuclear fuel reprocessing facility on the site. Our measurements of 36C1 in monitoring and production well waters, downgradient from disposal wells and seepage ponds, found easily detectable, nonhazardous concentrations of this radionuclide from the point of injection to the INEL southern site boundary. Comparisons are made between 3 H and 36 Cl concentrations in aquifer water and the advantages of 36 C1 as a tracer of subsurface-water dynamics at the site are discussed.

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USGS2005

Geology of the Payette National Forest and vicinity, west-central Idaho

Before the Late Cretaceous, the eastern and western parts of the geologically complex Payette National Forest, as divided by the Salmon River suture, had fundamentally different geologic histories. The eastern part is underlain by Mesoproterozoic to Cambrian(?) rocks of the Laurentian (Precambrian North American) continent. Thick Mesoproterozoic units, which are at least in part equivalent in age to the Belt Supergroup of northern Idaho and western Montana, under-went Mesoproterozoic metamorphic and deformational events, including intrusion of Mesoproterozoic plutons. During the Neoproterozoic to early Paleozoic, the western edge of Laurentia was rifted. This event included magmatism and resulted in deposition of rift-related Neoproterozoic to Lower Cambrian(?) volcanic and sedimentary rocks above Mesoproterozoic rocks. The western part of the forest is underlain by upper Paleozoic to lower Mesozoic island-arc volcanic and sedimentary rocks. These rocks comprise four recognized island-arc terranes that were amalgamated and intruded by intermediate-composition plutons, probably in the Late Jurassic and Early Cretaceous, and then sutured to Laurentia along the Salmon River suture in the Late Cretaceous. The Salmon River suture formed as a right-lateral, transpressive fault. The metamorphic grade and structural complexity of the rocks increase toward the suture from both sides, and geochemical signatures in crosscutting plutonic rocks abruptly differ across the crustal boundary. Having been reactivated by younger structures, the Salmon River suture forms a north-trending topographic depression along Long Valley, through McCall, to the Goose Creek and French Creek drainages. During the last stages of metamorphism and deformation related to the suture event, voluminous plutons of the Idaho batholith were intruded east of the suture. An older plutonic series is intermediate in composition and preserved as elongated and deformed bodies near the suture and as parts of roof pendants to younger intrusions to the east. A younger magma series consists of undeformed, marginally peraluminous plutons that formed east of the suture after accretion. After suture-related compression, crustal extension resulted in voluminous volcanic and plutonic rocks of the Eocene Challis magmatic complex on the east side of the forest. Extension, from the Late Cretaceous to post-Miocene, uplifted the area of the Idaho batholith relative to the western part of the forest and formed dominant highlands along the Snake River. Extensional basins also formed such that, in the Miocene, the Columbia River Basalt Group and related basaltic lavas flowed over most of the lower elevations on the western side of the forest and redirected erosional debris into north-trending, fault-controlled drainages and young sedimentary basins.

Idaho↗
USGS2005

Long-range movements and breeding dispersal of Prairie Falcons from southwest Idaho

From 1999–2003, we tracked movements of adult female Prairie Falcons ( Falco mexicanus ) using satellite telemetry to characterize long-range movement patterns and breeding dispersal. We radio marked 40 falcons from April–May on their nesting grounds in the Snake River Birds of Prey National Conservation Area in southwest Idaho. All falcons with functioning transmitters left the Snake River Canyon from late June through mid-July. Most headed northeast across the Continental Divide to summering areas in Montana, Alberta, Saskatchewan, and the Dakotas. Prairie Falcons stayed at their northern summer areas for 1–4 months before heading to the southern Great Plains or to southwest Idaho. The Great Plains was a key migration pathway. Important wintering areas included the Texas Panhandle and southwest Idaho. Most falcons completed their seasonal migrations within 2 weeks. Use of widely separated nesting, summering, and wintering areas appears to be a strategy to exploit seasonally abundant prey resources. Most falcons had three or fewer use areas during the nonbreeding season, and falcons showed a high degree of fidelity to their use areas during each season. At least 21 falcons returned to nest within 2.5 km of where they nested in the previous year, but one falcon moved to a new nesting area 124 km south of her previous breeding area. Prairie Falcon movements suggest large-scale connectivity of grassland and shrubsteppe landscapes throughout western North America. Conservation of Prairie Falcons must be an international effort that considers habitats used during both nesting and non-nesting seasons.

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USGS2005

Evolution of a late Cenozoic supradetachment basin above a flat-on-flat detachment with a folded lateral ramp, SE Idaho

Uplift and exposure of the Bannock detachment system and the synextensional basin fill deposits of the Salt Lake Formation provide a unique exposure of the three-dimensional geometries of a low-angle normal fault system and the stratal architecture of the overlying supradetachment basin. Within this system, structural and stratigraphic analyses, outcrop patterns, tephra geochronology, and geological cross sections document several important relationships: (1) the Bannock detachment system developed above the Sevierage Cache-Pocatello culmination and resembles the Sevier Desert detachment in its geometry, structural setting, and kinematic evolution; (2) the Bannock detachment system initiated and slipped at low angles; (3) flat-on-flat, ramp-flat, and lateral ramp geometries, as well as excision, can significantly affect the hanging wall deformation style due to the shallow depth (~2–4 km) of the Bannock detachment fault during late stages of slip; (4) late Miocene–Pliocene tuffaceous synrift deposits of the Salt Lake Formation record deposition in a supradetachment basin, display an unroofing sequence, and a three-stage evolution that includes pre-translation, translation, and breakup phases. Recycled pre-translation and translation phase deposits are diagnostic of this evolution; and (5) beginning in mid- to late Pliocene time, high-angle, north-striking Basin and Range faults disrupted and dismembered the Bannock detachment system.

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USGS2005

Geology and stratigraphy of the Challis Volcanic Group and related rocks, Little Wood River area, south-central Idaho

The southwestern part of the Challis volcanic field occupies the valley of the Little Wood River and its tributaries in the Hailey and Idaho Falls 1°×2° quadrangles of south-central Idaho. The Little Wood River area is a structurally controlled topographic basin that is partly filled by Eocene Challis Volcanic Group and younger rocks. Rock types in the Challis Volcanic Group of the Little Wood River area include, in order of decreasing abundance, andesite lava flows and tuff breccia, dacite lava flows and flow breccia, volcaniclastic sedimentary rocks, lithic tuff, nonvolcanic conglomerate, and rhyolite dikes. A basal nonvolcanic conglomerate, that locally rests on upper Paleozoic sedimentary rocks at a regional unconformity, was deposited prior to eruption of volcanic rocks. Andesite was the first volcanic rock erupted and is a voluminous sequence as thick as 3,000 ft (1,000 m). Locally thick volcaniclastic sedimentary rocks accumulated in topographic lows. A sharp transition marks the beginning of dacite eruption from fissures and flow-dome complexes. Dacite flows and breccias are as thick as 2,000 ft (600 m). An upper volcaniclastic unit was deposited in paleotopographic lows following emplacement of the main dacite unit. Next, a widespread, distinctive, lithic rich ash flow tuff, correlated with the tuff of Stoddard Gulch, was deposited over much of the area. Deposition of the tuff was followed by eruption of thin andesite and dacite lava flows and deposition of conglomeratic sedimentary rocks. The entire sequence was then intruded by a dacite flow-dome complex composed of at least three separate intrusions. The Challis Volcanic Group in the study area is calcalkaline. Andesitic rocks are typically high potassium basaltic andesite, high potassium andesite, shoshonite, and banakite (latite). Dacitic rocks are high potassium dacite and trachyte. Tuffs and vitrophyres range in composition from basaltic andesite to trachyte. The paleotopographic basin in which the Challis Volcanic Group accumulated was in part structurally controlled by preexisting west and northwest trending normal faults. Paleorelief was probably more than 2,000 ft (600 m). Rocks of the Challis Volcanic Group typically dip about 36° E., probably owing to Eocene extension and (or) basin-and-range faulting and tilting. Some potential for precious- and base- metal hydrothermal deposits is associated with northeast trending lineaments, argillic alteration, and rhyolite dikes.

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USGS2005

Precambrian crystalline basement map of Idaho: An interpretation of aeromagnetic anomalies

Idaho lies within the northern sector of the U.S. Cordillera astride the boundary between the Proterozoic continent (Laurentia) to the east and the Permian to Jurassic accreted terranes to the west. The continental basement is mostly covered by relatively undeformed Mesoproterozoic metasedimentary rocks and intruded or covered by Phanerozoic igneous rocks; accordingly, knowledge of the basement geology is poorly constrained. Incremental knowledge gained since the pioneering studies by W. Lindgren, C.P. Ross, A.L. Anderson, A. Hietanen, and others during the early- and mid-1900's has greatly advanced our understanding of the general geology of Idaho. However, knowledge of the basement geology remains relatively poor, partly because of the remoteness of much of the region plus the lack of a stimulus to decipher the complex assemblage of high-grade gneisses and migmatite of central Idaho. The availability of an updated aeromagnetic anomaly map of Idaho (North American Magnetic Anomaly Group, 2002) provides a means to determine the regional Precambrian geologic framework of the State. The combined geologic and aeromagnetic data permit identification of previously unrecognized crystalline basement terranes, assigned to Archean and Paleoproterozoic ages, and the delineation of major shear zones, which are expressed in the aeromagnetic data as linear negative anomalies (Finn and Sims, 2004). Limited geochronologic data on exposed crystalline basement aided by isotopic studies of zircon inheritance, particularly Bickford and others (1981) and Mueller and others (1995), provide much of the geologic background for our interpretation of the basement geology. In northwestern United States, inhomogeneities in the basement inherited from Precambrian tectogenesis controlled many large-scale tectonic features that developed during the Phanerozoic. Two basement structures, in particular, provided zones of weakness that were repeatedly rejuvenated: (1) northeast-trending ductile shear zones developed on the northwest margin of the Archean Wyoming province during the Paleoproterozoic Trans-Montana orogeny (Sims and others, 2004), and (2) northwest-trending intra-continental faults of the Mesoproterozoic Trans-Rocky Mountain strike-slip fault system (Sims, unpub. data, 2003). In this report, geologic ages are reported in millions of years (Ma) and generalized ages are given in billions of years (Ga). The subdivision of Precambrian rocks used herein is the time classification recommended by the International Union of Geological Sciences (Plumb, 1991).

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USGS2005

Stream-sediment geochemistry in mining-impacted streams: Prichard, Eagle, and Beaver Creeks, northern Coeur d'Alene mining district, northern Idaho

This report presents the results of one aspect of an integrated watershed-characterization study that was undertaken to assess the impacts of historical mining and milling of silver-lead-zinc ores on water and sediment composition and on aquatic biota in streams draining the northern part of the Coeur d'Alene Mining District in northern Idaho. We present the results of chemical analyses of 62 samples of streambed sediment, 19 samples of suspended sediment, 23 samples of streambank soil, and 29 samples of mine- and mill-related artificial- fill material collected from the drainages of Prichard, Eagle, and Beaver Creeks, all tributaries to the North Fork of the Coeur d'Alene River. All samples were sieved into three grain-size fractions (<0.063, 0.063-0.25, and 0.25-1.0 mm) and analyzed for 40 elements after four-acid digestion by inductively coupled plasma atomic-emission spectrometry and for mercury by continuous-flow cold-vapor atomic-absorption spectrometry in the U.S. Geological Survey laboratory in Denver, Colo. Historical mining of silver-lead-zinc ores in the headwater reaches of the Prichard Creek, Eagle Creek, and Beaver Creek drainages has resulted in enrichments of lead, zinc, mercury, arsenic, cadmium, silver, copper, cobalt, and, to a lesser extent, iron and manganese in streambed sediment. Using samples collected from the relatively unimpacted West Fork of Eagle Creek as representative of background compositions, streambed sediment in the vicinity of the mines and millsites has Pb and Zn contents of 20 to 100 times background values, decreasing to 2 to 5 times background values at the mouth of the each stream, 15 to 20 km downstream. Lesser enrichments (<10 times background values) of mercury and arsenic also are generally associated with, and decrease downstream from, historical silver-lead-zinc mining in the drainages. However, enrichments of arsenic and, to a lesser extent, mercury also are areally associated with the lode gold deposits along Prichard Creek near Murray, which were not studied here. Metal contents in samples of unfractionated suspended sediment collected during a high-flow event in April 2000 are generally similar to, but slightly higher than, those in the fine (<0.063-mm grain size) fraction of streambed sediment from the same sampling site. Although metal enrichment in streambed sediment typically begins adjacent to the mine portals and their associated mine-waste rock dumps, volumetrically larger inputs of metal-enriched materials were contributed by the ore-concentration millsites and their associated, more finely ground, more metal rich mill-tailings impoundments

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USGS2005

Review of the transport of selected radionuclides in the interim risk assessment for the Radioactive Waste Management Complex, Waste Area Group 7 Operable Unit 7-13/14, Idaho National Engineering and Environmental Laboratory, Idaho

The U.S. Department of Energy (DOE) requested that the U.S. Geological Survey conduct an independent technical review of the Interim Risk Assessment (IRA) and Contaminant Screening for the Waste Area Group 7 (WAG-7) Remedial Investigation, the draft Addendum to the Work Plan for Operable Unit 7-13/14 WAG-7 comprehensive Remedial Investigation and Feasibility Study (RI/FS), and supporting documents that were prepared by Lockheed Martin Idaho Technologies, Inc. The purpose of the technical review was to assess the data and geotechnical approaches that were used to estimate future risks associated with the release of the actinides americium, uranium, neptunium, and plutonium to the Snake River Plain aquifer from wastes buried in pits and trenches at the Subsurface Disposal Area (SDA). The SDA is located at the Radioactive Waste Management Complex in southeastern Idaho within the boundaries of the Idaho National Engineering and Environmental Laboratory. Radionuclides have been buried in pits and trenches at the SDA since 1957 and 1952, respectively. Burial of transuranic wastes was discontinued in 1982. The five specific tasks associated with this review were defined in a ?Proposed Scope of Work? prepared by the DOE, and a follow-up workshop held in June 1998. The specific tasks were (1) to review the radionuclide sampling data to determine how reliable and significant are the reported radionuclide detections and how reliable is the ongoing sampling program, (2) to assess the physical and chemical processes that logically can be invoked to explain true detections, (3) to determine if distribution coefficients that were used in the IRA are reliable and if they have been applied properly, (4) to determine if transport model predictions are technically sound, and (5) to identify issues needing resolution to determine technical adequacy of the risk assessment analysis, and what additional work is required to resolve those issues.

Idaho↗
USGS2005

Status of and changes in water quality monitored for the Idaho statewide surface-water-quality network, 1989&mdash;2002

The Idaho statewide surface-water-quality monitoring network consists of 56 sites that have been monitored from 1989 through 2002 to provide data to document status and changes in the quality of Idaho streams. Sampling at 33 sites has covered a wide range of flows and seasons that describe water-quality variations representing both natural conditions and human influences. Targeting additional high- or low-flow sampling would better describe conditions at 20 sites during hydrologic extremes. At the three spring site types, sampling covered the range of flow conditions from 1989 through 2002 well. However, high flows at these sites since 1989 were lower than historical high flows as a result of declining ground-water levels in the Snake River Plain. Summertime stream temperatures at 45 sites commonly exceeded 19 and 22 degrees Celsius, the Idaho maximum daily mean and daily maximum criteria, respectively, for the protection of coldwater aquatic life. Criteria exceedances in stream basins with minimal development suggest that such high temperatures may occur naturally in many Idaho streams. Suspended-sediment concentrations were generally higher in southern Idaho than in central and northern Idaho, and network data suggest that the turbidity criteria are most likely to be exceeded at sites in southern Idaho and other sections of the Columbia Plateaus geomorphic province. This is probably because this province has more fine-grained soils that are subject to erosion and disturbance by land uses than the Northern Rocky Mountains province of northern and central Idaho has. Although erodable soils are likely a cause of elevated turbidities, suspended-sediment concentrations were not strongly correlated with turbidities. Dissolved-solids and hardness concentrations were strongly correlated. This is probably because the limestones present in some basins are more soluble than the igneous rocks that predominate in others. Low hardness in streams of northern Idaho, where watersheds are underlain by resistant igneous rocks, enhances the toxicity of some trace elements to aquatic life in these streams. Only a few measurements of dissolved-oxygen concentrations at six sites were less than 6.0 milligrams per liter, the Idaho minimum criterion for protection of aquatic organisms. High supersaturations of dissolved oxygen at four sites suggest excessive photosynthetic activity by algal communities. Nighttime monitoring would help determine whether dissolved-oxygen concentrations at these sites might fall below the Idaho criterion. Data from four sites suggest that dissolved-oxygen concentrations may have decreased over time. The pH at 15 sites sometimes fell outside the range specified (6.5-9.0) for the protection of aquatic organisms in Idaho streams. Values exceeded 9.0 at 10 sites, probably because of excessive algal photosynthetic activity in waters where carbonate rocks are present. Values were sometimes less than 6.5 at five sites in areas of mountain bedrock geology where pH is likely to be naturally low. Mining activities also may contribute to low pH at some of these sites. Inorganic nitrogen and total phosphorus concentrations commonly exceeded those considered sufficient for supporting excess algal production (0.3 and 0.1 milligrams per liter, respectively). Data from a few sites suggest that nitrogen and(or) phosphorus concentrations might be changing over time. Low concentrations of nitrogen and phosphorus at six sites, most representing forested basins, might make them good candidates as reference sites that represent naturally occurring nutrient concentrations. Trace elements examined for this report were cadmium, copper, lead, mercury, selenium, and zinc. In water, many trace-element concentrations were below the minimum analytical reporting levels. Concentrations of cadmium, copper, lead, and zinc generally were highest in mined and other mineral-rich basins in northern Idaho. Concentrations of mercury were

Idaho↗
USGS2005

Development of property-transfer models for estimating the hydraulic properties of deep sediments at the Idaho National Engineering and Environmental Laboratory, Idaho

Because characterizing the unsaturated hydraulic properties of sediments over large areas or depths is costly and time consuming, development of models that predict these properties from more easily measured bulk-physical properties is desirable. At the Idaho National Engineering and Environmental Laboratory, the unsaturated zone is composed of thick basalt flow sequences interbedded with thinner sedimentary layers. Determining the unsaturated hydraulic properties of sedimentary layers is one step in understanding water flow and solute transport processes through this complex unsaturated system. Multiple linear regression was used to construct simple property-transfer models for estimating the water-retention curve and saturated hydraulic conductivity of deep sediments at the Idaho National Engineering and Environmental Laboratory. The regression models were developed from 109 core sample subsets with laboratory measurements of hydraulic and bulk-physical properties. The core samples were collected at depths of 9 to 175 meters at two facilities within the southwestern portion of the Idaho National Engineering and Environmental Laboratory-the Radioactive Waste Management Complex, and the Vadose Zone Research Park southwest of the Idaho Nuclear Technology and Engineering Center. Four regression models were developed using bulk-physical property measurements (bulk density, particle density, and particle size) as the potential explanatory variables. Three representations of the particle-size distribution were compared: (1) textural-class percentages (gravel, sand, silt, and clay), (2) geometric statistics (mean and standard deviation), and (3) graphical statistics (median and uniformity coefficient). The four response variables, estimated from linear combinations of the bulk-physical properties, included saturated hydraulic conductivity and three parameters that define the water-retention curve. For each core sample,values of each water-retention parameter were estimated from the appropriate regression equation and used to calculate an estimated water-retention curve. The degree to which the estimated curve approximated the measured curve was quantified using a goodness-of-fit indicator, the root-mean-square error. Comparison of the root-mean-square-error distributions for each alternative particle-size model showed that the estimated water-retention curves were insensitive to the way the particle-size distribution was represented. Bulk density, the median particle diameter, and the uniformity coefficient were chosen as input parameters for the final models. The property-transfer models developed in this study allow easy determination of hydraulic properties without need for their direct measurement. Additionally, the models provide the basis for development of theoretical models that rely on physical relationships between the pore-size distribution and the bulk-physical properties of the media. With this adaptation, the property-transfer models should have greater application throughout the Idaho National Engineering and Environmental Laboratory and other geographic locations.

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