1999 – ONGOING
COST DONATED BY EPA
Biological assessment of the Willow Creek watershed consists of several components, including evaluations of fish communities, benthic macro-invertebrate composition, and in-stream, riparian and upland habitat characteristics. All of these components are necessary in assessing the aquatic community and the factors that may potentially be effecting those communities. The assessment is designed to provide a sampling of representative locations downstream of mine and mill sites that may be impacted by those sites. The information collected in previous years provides a baseline condition for the watershed that allows for future reclamation effectiveness monitoring.
The Willow Creek Reclamation Committee began characterization of water quality in 1999. Investigations have included surface water associated with Willow Creek and its tributaries; the Rio Grande; alluvial groundwater below Creede and near selected mine sites; and deep groundwater associated with mine drainage. For more information on the deep groundwater investigations, see “The Nelson Tunnel.”
1. REPORT ON SURFACE AND MINE WATER SAMPLING AND MONITORING IN WILLOW CREEK WATERSHED, MINERAL COUNTY, CO
This report presents the results of four synoptic sampling events which were conducted from 1999 to 2002. The sampling events included sampling of surface waters, mine waters and groundwater. Sampling included flow measurements of stream water and mine discharges so that flow weighted mass loading could be calculated.
2. REPORT ON CHARACTERIZATION OF GROUNDWATER IN THE ALLUVIAL DEPOSITS BENEATH THE FLOODPLAIN OF WILLOW CREEK BELOW CREEDE
This report presents a discussion of the Willow Creek floodplain and the results of the groundwater sampling conducted from 1999 to 2002. The installation of monitoring wells in the floodplain and near selected mine sites provided information on groundwater quality and associations with water quality in Willow Creek and the Rio Grande.
3. RESULTS OF GROUNDWATER TRACING EXPERIMENTS IN THE NELSON-WOOSTER-HUMPHREY TUNNEL
This report describes ground-water tracing investigation done by Cambrian Groundwater in the Nelson -Wooster – Humphrey Tunnel system during September 2001. A fluorescent dye tracer was injected and recovered at various locations inside and outside the mine system and the results used to infer flow conditions in the tunnel. Tritium data that had been collected were also interpreted. Using these two tracers enables water tracing to be done in mixtures of ground waters that have residence times of hours to decades. Quantitative tracing of ground water enables an estimate to be made of hydraulic and other parameters along pathways where parts of subterranean pathways are not accessible for physical examination.
4. PRIVATE WATER WELLS IN AND NEAR THE CREEDE GRABEN, NORTH OF CREEDE, COLORADO
In March 2003, the WCRC authorized Robert Kirkham (Consulting Geologist) to investigate private water wells located in and near the Creede graben north of the town of Creede, Colorado. The investigation included (1) the collection of publicly available data held by the Colorado Division of Water Resources, State Engineer’s Office (CDWR) and (2) locating the deep wells in the field and determining UTM coordinates for the deep wells. The purpose of these investigations was to provide preliminary data for water table mapping and to determine directions for further investigations of deep groundwater.
5. COMPARISON OF ELECTROMAGNETIC AND NATURAL POTENTIAL GEOPHYSICAL INVESTIGATIONS NEAR THE EMPERIOUS TAILINGS PILE, CREEDE, COLORADO
6. WILLOW-LEAF ANALYSIS DETERMINES EXTENT OF MINE CONTAMINATION PLUME ON THE WILLOW CREEK FLOODPLAIN, CREEDE, COLORADO
In 2003, a feasibility study was conducted to determine the applicability of using metal concentrations in willow leaves as an indicator of groundwater contamination. This report indicated that willow leaves sequestered elevated levels of metals in contaminated areas versus background conditions.
7. EVALUATION OF METAL LOADING TO STREAMS NEAR CREEDE, COLORADO, AUGUST AND SEPTEMBER 2000
8. NELSON TUNNEL WATER TREATMENT FEASIBILITY STUDY AND BENCH SCALE TESTING
The WCRC has found that the Nelson Tunnel has been found to be the primary contributor of metal contamination to Willow Creek. In 2005, the WCRC contracted McLaughlin Rincón to evaluate the feasibility of treating discharge from the Nelson Tunnel to reduce metals loading to Willow Creek and to the Rio Grande. The study investigated conventional chemical, biological, and electrical treatment methods, and examined potential treatment locations, the potential to use hydropower generation, and the potential for heat recovery. McLaughlin Rincón recommended use of chemical hydroxide precipitation to treat Nelson Tunnel water.
Computer modeling suggested that chemical precipitation treatment methods may not be able to remove some metal contaminants in Nelson Tunnel water to table value standards. The WCRC performed bench scale testing to evaluate treatment of actual Nelson Tunnel water with lime and caustic soda. The bench scale tests indicated that treatment using hydroxides should be able to remove metals to effluent standards. Funding for this study was provided by a grant from the U.S. Environmental Protection Agency.
9. AQUATIC RESOURCES ASSESSMENT OF THE WILLOW CREEK WATERSHED
This report provides a summary of environmental assessment data collected from the Willow Creek Watershed through the leadership of the Willow Creek Reclamation Committee in relation to aquatic resources. Many thanks to the U.S. EPA Region 8 Ecosystems Protection Program, under the direction of Mike Wireman and Karl Hermann, who developed this report in partnership with the WCRC.