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Taken from the first paragraph of the introduction: The Rocky Mountains, the great backbone of North America, extend 5,000 kilometers from New Mexico to Canada. The elevations range from about 1,500 meters along the plains to 4,399 meters, and the widths range from 120 to 650 kilometers (Lavender 1975). The Rocky Mountains are composed of many mountain ranges with unique ecological features. For example, 20 ranges make up the Rocky Mountains in and adjacent to Wyoming (Knight 1994). The natural beauty, abundant wildlife, and fresh water have attracted human inhabitants for the last 10,000–12,000 years (Fig. 1). Published in Status and Trends of the Nation's Biological Resources, on pages 473 - 504, in 1998.
Natural and mining-related dissolved-constituent concentrations need to be distinguished in a water- shed affected by abandoned mines to prioritize subbasins for remediation and to assist with the establish- ment of water-quality standards. The oxygen isotopes of dissolved sulfate can be used to distinguish betweennaturalandmining-relatedsourcesofdissolvedconstituents. Severalmethodsemployingtheoxy- gen isotopes of dissolved sulfate can be used to determine the relative amounts of natural and mining- related dissolved constituents in water: (1) the isotope-dilution equation for simple mixing zones (two sources and one receiving stream); (2) the isotope mass-balance equation for streams receiving dissolved sulfate...
The Wyoming Landscape Conservation Initiative (WLCI) was launched in 2007 in response to concerns about threats to the State s world class wildlife resources, especially the threat posed by rapidly increasing energy development in southwest Wyoming. The overriding purpose of the WLCI is to assess and enhance aquatic and terrestrial habitats at a landscape scale, while facilitating responsible energy and other types of development. The WLCI includes partners from Federal, State, and local agencies, with participation from public and private entities, industry, and landowners. As a principal WLCI partner, the U.S. Geological Survey (USGS) provides multidisciplinary scientific and technical support to inform decisionmaking...
Partitioning of zinc (Zn) between dissolved and colloidal phases was studied in the upper Animas River. Most of the Zn was dissolved in the water column, but a variable fraction of the total Zn was associated with aluminum (Al)- and iron (Fe)-rich colloidal particles. Colloids were supplied to the river by tributary creeks that drain areas with natural sulfide mineral deposits and debris from abandoned mines. The fraction of the total Zn that was in the colloidal phase increased with pH in the river, indicating the possibility of adsorption by colloidal Al and Fe. The influence of pH was confirmed in laboratory experiments in which larger fractions of the total Zn were associated with the colloids when pH was increased...
Six stratigraphic units are recognized as favorable for the occurrence of uranium deposits that meet the minimum size and grade requirements of the U.S. Department of Energy in the Cortez 1�? x 2�? Quadrangle, Utah and Colorado. These units include the Jurassic Salt Wash, Recapture, and Brushy Basin Members of the Morrison Formation and the Entrada Sandstone, the Late Triassic Chinle Formation, and the Permian Cutler Formation. Four areas are judged favorable for the Morrison members which include the Slick Rock, Montezuma Canyon, Cottonwood Wash and Hatch districts. The criteria used to determine favorability include the presence of the following (1) fluvial sandstone beds deposited by low-energy streams; (2) actively...
Categories: Publication; Types: Citation; Tags: U.S. Geological Survey
The geochemistry of rare earth element (REE) variations in acid waters is being studied as part of the U. S. Geological Survey Abandoned Mine Lands Initiative in two pilot watersheds, upper Animas, Colorado and Boulder, Montana. The following objectives are under investigation: (1) comparison of acid mine waters and naturally acidic springs, (2) determination of whether the dominant control on REEs in acid waters is source-related or post-dissolution process-related, (3) determination of the role of iron and aluminum colloid formation on the REE patterns, (4) address the utility of REE geochemistry in acid waters as an analogue for the actinides, and (5) produce a Standard Reference Water Sample for REEs. Results...
Scientists participating in the USGS Abandoned Minelands Initiative have quantified metal concentrations and loadings from mining-related and natural background sources in the upper Animas River of southwestern Colorado, with the goal of guiding remediation decisions by federal land- management agencies. We have compared site-specific toxicity thresholds with frequencies of dissolved metal concentrations in stream water to evaluate the contributions of zinc and copper to toxic effects in fish and aquatic invertebrates in the upper Animas. Median lethal concentrations (LC50s) of zinc and copper were determined for fathead minnows, Pimephales promelas, and amphipods, Hyalella azteca, from seven-day toxicity tests...
Determination of the pre-mining geochemical baseline in bed sediments and the paleoecology in a watershed impacted by historical mining activity is of utmost importance in establishing watershed restoration goals. We have approached this problem in the Animas River watershed using geomorphologic mapping methods to identify old pre-mining sediments. A systematic evaluation of possible sites resulted in collection of a large number of samples of pre-mining sediments, overbank sediments, and fluvial tailings deposits from more than 50 sites throughout the watershed. Chemical analysis of individual stratigraphic layers has resulted in a chemical stratigraphy that can be tied to the historical record through geochronological...
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Seasonal variation of metal concentrations in the upper Animas River watershed of Colorado may strongly influence toxic effects of stream water to aquatic biota. Loadings of dissolved metals to the upper Animas River and tributaries are greatest during summer, during high stream discharge from snowmelt and monsoonal rains, but adverse effects on stream biota may be greater during winter low-flow periods, when concentrations of dissolved metals are greatest. We evaluated the toxicity of stream water from four sites to fathead minnows (Pimephales promelas) and amphipods (Hyalella azteca) in late summer 1998 and late winter 1999. Stream water was more toxic in winter than in summer, consistent with greater concentrations...


    map background search result map search result map Seasonal variation in toxicity of streams affected by acid mine drainage Seasonal variation in toxicity of streams affected by acid mine drainage