Quentin D. Skinner

Chemistry of trace elements in coalbed methane product water.

Extraction of methane (natural gas) from coal deposits is facilitated by pumping of aquifer water. Coalbed methane (CBM) product water, produced from pumping ground water, is discharged into associated unlined holding ponds. The objective of this study was to examine the chemistry of trace elements in CBM product water at discharge points and in associated holding ponds across the Powder River Basin, Wyoming. Product water samples from discharge points and associated holding ponds were collected from the Cheyenne River (CHR), Belle Fourche River (BFR), and Little Powder River (LPR) watersheds during the summers of 1999 and 2000. Samples were analyzed for pH, Al (aluminum), As (arsenic), B (boron), Ba (barium), Cr (chromium), Cu (copper), F (fluoride), Fe (iron), Mn (manganese), Mo (molybdenum), Se (selenium), and Zn (zinc). Chemistry of trace element concentrations were modeled with the MINTEQA2 geochemical equilibrium model. Results of this study show that pH of product water for three watersheds increased in holding ponds. For example the pH of CBM product water increased from 7.21 to 8.26 for LPR watershed. Among three watersheds, the CBM product water exhibited relatively less change in trace element concentrations in CHR watershed holding ponds. Concentration of dissolved Al, Fe, As, Se, and F in product water increased in BFR watershed holding ponds. For example, concentration of dissolved Fe increased from 113 to 135 microg/L. Boron, Cu, and Zn concentrations of product water did not change in BFR watershed holding ponds. However, concentration of dissolved Ba, Mn, and Cr in product water decreased in BFR watershed holding ponds. For instance, Ba and Cr concentrations decreased from 445 to 386 microg/L and from 43.6 to 25.1 microg/L, respectively. In the LPR watershed, Al, Fe, As, Se, and F concentrations of product water increased substantially in holding ponds. For example, Fe concentration increased from 192 to 312 microg/L. However, concentration of dissolved Ba, Mn, Cr, and Zn decreased in holding ponds. Geochemical modeling calculations suggested that observed increase of Al and Fe concentrations in holding ponds was due to increase in concentration of Al(OH)(4)(-) and Fe(OH)(4)(-) species in water which were responsible for pH increases. Decreases in Ba, Mn, Cr, and Zn concentrations were attributed to the increase in pH, resulting in precipitates of BaSO(4) (barite), MnCO(3) (rhodochrosite), Cr(OH)(2) (chromium hydroxide), and ZnCO(3) (smithsonite) in pond waters, respectively.

New Technique for Measuring Fine Sediment in Streams

Abstract Techniques commonly used to measure fine-sediment accumulation in streambed gravels can be labor and equipment intensive. We evaluated the sediment trapping capabilities of modified Whitlock–Vibert boxes under both laboratory and field conditions and compared the accumulated fine sediment to that contained in adjacent gravels as indicated by McNeil core samples. Our results suggest the boxes can be used as an alternative to core sampling for monitoring intergravel fine sediment levels. Advantages include ease of transport to remote field sites, small sample volumes, and reduced analysis time. Problems encountered were displacement of boxes by flood and ice flows and inundation by large sediment spills.

Assessment of Best-Management Practice Effects on Rangeland Stream Water Quality Using Multivariate Statistical Techniques

Abstract Quantifying the effects of watershed improvement efforts is critical to agencies responsible for protecting water resources of the semiarid western United States. A complex water quality data set collected from 1994 to 2004 of upper Muddy Creek Basin was subjected to cluster analysis, discriminant analysis, and canonical correlation analysis to improve understanding of basin fluvial processes and to investigate whether livestock grazing best-management practices (BMPs) improved the water quality of the watershed. Hierarchical agglomerative cluster analysis grouped nine sampling sites into two clusters based on similarity of biological indices, separating the clusters into aquatic communities more and less tolerant of degraded stream conditions. Discriminant analysis yielded strong spatial and temporal distinctions, providing important data reduction by rendering seven key parameters (total dissolved solids [TDS], temperature, elevation, slope, 10-dominant taxa, percent collector-gatherers, and percent Plecoptera) for the spatial variation and four parameters (TDS, dissolved oxygen, total taxa, and community tolerance quotient) for the temporal variation. Canonical correlation analysis identified strong negative relationships among Plecoptera taxa and total taxa with TDS and turbidity in addition to strong positive associations with elevation, slope, and channel substrate weighted embeddedness value. Despite the onset of severe drought midway through the study period, overall reductions of 13% for TDS and a 30% increase in macroinvertebrate total taxa occurred across years, strongly suggesting that improvements in water quality were correlated to BMPs that stabilized stream channels and improved the condition of riparian areas.

A Test of Factors Hypothesized to Influence Biomass of Salmonids in Rocky Mountain Streams

ABSTRACT Weight-length relationships provide a tool to assess the body condition of brown trout (Salmo trutta) populations inhabiting stream reaches where stressors, such as metals, have chronic, sub-lethal toxic impacts. A previously published brown trout standard-weight equation, Ws, overestimated Colorado brown trout weights. Weight-length data from 16 Colorado brown trout populations (n = 9, 8 16) were used to develop a regional standard weight (Wcl) equation based on fish from waters free of metal contamination. Relative-weights (Wr) were then compared between metal-contaminated and metal-free streams in Colorado using the Wcl equation. Brown trout Wrs were lower in metal contaminated streams than in stream reaches uncontaminated by metals. The development and use of regional standard weight equations is recommended to help assess the weight of brown trout inhabiting metal-contaminated stream reaches.

Assessment of Flushing Flow Recommendations in a Steep, Rough, Regulated Tributary

Alteration of stream flow regime and sediment loading from water development activities can result in both short- and long-term changes in channel morphology and conveyance capacity. Subsequently, the condition of the aquatic habitat can be affected. In recent years, much research and development effort has been directed toward the determination of suitable instream flows to maintain fisheries habitat in regulated streams (Stalnaker & Arnette 1976; Wesche & Rechard 1980). However, there are several facets of the instream flow problem which have not been adequately investigated, one involving the recommendation of flushing flows to simulate the peak runoff hydrograph characteristics of most unregulated streams (Reiser et al. 1985).

Clipping Frequency Affects Canopy Volume and Biomass Production in Planeleaf Willow (Salix planifolia var. planifolia Prush)

Abstract Willows (Salix) are often a key component of riparian ecosystems and are often browsed by both wildlife and livestock. However, little is understood about how the frequency of browsing affects aboveground and belowground willow production. The objectives of this study were to determine how the frequency of simulated browsing events in a controlled environment affected 1) the aboveground, belowground, and total biomass production and 2) the canopy volume of planeleaf willow (Salix planifolia var. planifolia Prush) plants. The experiment was a completely randomized block design consisting of 2 groups of willow plants with different clipping histories. Within each group, plants were randomly assigned to 1 of 11 subgroups. Clipping events comprised of all combinations of early, middle, and late season periods were imposed on the treatment subgroups, while 1 subgroup served as the control. Canopy volume measurements were made before and after each clipping event. Canopy volume change was related to the harvested twig length (cm) and weight (g). Results suggested that frequency of clipping alone did not explain differences in aboveground and belowground willow production. Instead, willow production was influenced by an accumulation of specific combinations of seasonal clipping events and was dependent on the clipping history of the plants. Early season clipping, alone or in combination with other events, was more detrimental to willows with prior clipping histories than middle or late season clipping treatments. Willow with prior clipping histories treated in either the middle or late seasons, and the late/middle combination produced more than the controls. These results should be verified in willow communities subjected to natural environmental variations and browsing.

Wild Ungulate Herbivory of Willow on Two National Forest Allotments in Wyoming

Abstract Willows (Salix) are important riparian plants and often used to indicate riparian condition. Many herbivores feed on willows, but there is limited information about willow browsing by wildlife except in national parks. This study was conducted to estimate wild ungulate herbivory of willow on two US Forest Service allotments in northern Wyoming and to compare these values to published estimates for national parks. We also compared total annual and seasonal willow utilization by wildlife between sites dominated by willows of different heights. The effects of height category, site, and season on willow utilization were determined with a repeated measures analysis. Four permanent willow utilization transects were established at each of six study sites per allotment on two allotments, in communities supporting planeleaf (Salix planifolia Pursh), Wolfs (Salix wolfii Bebb), Drummonds (Salix drummondiana Barratt ex Hook.), or Eastwoods (Salix eastwoodiae Cock. ex A. Heller) willow. Twenty-five twigs were marked per transect (distributed across 6–12 plants/transect). Lengths of marked twigs were recorded on four dates to estimate willow utilization for winter/spring, summer, and late summer/fall periods. Total annual willow utilization on one allotment (53%) was similar to published estimates for national parks (P  =  0.0864), whereas utilization for the other allotment (58%) was greater (P  =  0.0421) than national parks. Seasonal patterns of willow utilization differed among sites within height categories (P < 0.001). Total annual willow utilization by wildlife also varied by site within height category (P  =  0.0165) but was not greater for short (43–56%) versus tall (59–63%) willow communities. Wildlife browsing of willow in this study equaled, or exceeded, estimates for national parks, where concern has been expressed about willow community conditions. Generalizations about willow utilization for tall and short willow communities are problematic. Management decisions should be based on site-specific information as opposed to generalizations.