Publications

Ground water systems dominated by iron‐ or sulfate‐reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe2+) and sulfide (sum of H2S, HS−, and S= species and denoted here as “H2S”). This approach is based on the observation that concentrations of Fe2+ and H2S in ground water systems tend to be inversely related according to a hyperbolic function. That...

Over nearly two decades, the Water, Energy, and Biogeochemical Budgets (WEBB) small watershed research program of the U.S. Geological Survey (USGS) has documented how water and solute fluxes, nutrient, carbon, and mercury dynamics, and weathering and sediment transport respond to natural and humancaused drivers, including climate, climate change, and atmospheric deposition. Together with...

Effective remediation requires an understanding of the relative contributions of metals from all sources in a catchment, and that understanding must be based on a spatially detailed quantification of metal loading. A traditional approach to quantifying metal loading has been to measure discharge and chemistry at a catchment outlet. This approach can quantify annual loading and the...

Here the hydrogeochemical constraints of a tracer dilution study are combined with Fe and Zn isotopic measurements to pinpoint metal loading sources and attenuation mechanisms in an alpine watershed impacted by acid mine drainage. In the tested mountain catchment, δ56Fe and δ66Zn isotopic signatures of filtered stream water samples varied by ∼3.5‰ and 0.4‰, respectively. The inherent...

Vernal pools are sensitive environments that provide critical habitat for many species, including amphibians. These small water bodies are not always protected by pesticide label requirements for no-spray buffer zones, and the occurrence of pesticides in them is poorly documented. In this study, we investigated the occurrence of glyphosate, its primary degradation product...

Geomorphic changes in reconfi gured reaches of three Colorado rivers in response to floods in 2005 provide a benchmark for "restoration" assessment. Sedimententrainment potential is expressed as the ratio of the shear stress from the 2 yr, 5 yr, 10 yr, and 2005 floods to the critical shear stress for sediment. Some observed response was explained by the excess of flood shear stress...

Investigations within the Silverton caldera, in southwestern Colorado, used a combination of traditional geological mapping, alteration-assemblage mapping, and aqueous geochemical sampling that showed a relationship between geological and hydrologic features that may be used to better understand the provenance and evolution of the water. Veins containing fluorite, huebnerite, and...

[1] While it is widely recognized that highly permeable ‘large‐scale' fractures dominate chemical migration in many fractured aquifers, recent studies suggest that the pervasive ‘small‐scale’ fracturing once considered of less significance can be equally important for characterizing the spatial extent and residence time associated with transport processes. A detailed examination of...

Recent national concerns regarding the environmental occurrence of emerging contaminants (ECs) have catalyzed a series of recent studies. Many ECs are released into the environment through discharges from wastewater treatment plants (WWTPs) and other sources. In 2005, the U.S. Geological Survey and the City of Longmont initiated an investigation of selected ECs in a 13.8‐km reach of St...

Turquoise Lake is a water-supply reservoir located north of the historic Sugarloaf Mining district near Leadville, Colorado, USA. Elevated water levels in the reservoir may increase flow of low-quality water from abandoned mine tunnels in the Sugarloaf District and degrade water quality downstream. The objective of this study was to understand the sources of water to Dinero mine drainage...

Elevated selenium concentrations in streams are a water-quality concern in western Colorado. Sweitzer Lake was placed on the State 303(d) list as impaired with respect to dissolved selenium. In Colorado, the Water Quality Control Division of the Colorado Department of Public Health and Environment is required to develop total maximum daily loads of selenium for the 303(d) list segments...

Biodegradation of 17β-estradiol (E2), estrone (E1), and testosterone (T) was investigated in three wastewater treatment plant (WWTP) affected streams in the United States. Relative differences in the mineralization of [4-14C] substrates were assessed in oxic microcosms containing saturated sediment or water-only from locations upstream and downstream of the WWTP outfall in each system...