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Water Resources of Colorado

Determination of Instream Metal LoadsUsing Tracer-Injection and Synoptic-Sampling Techniques, Wightman Fork, Southwestern Colorado, July 1999

by Roderick F. Ortiz

Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 01-4167, 35 p., 12 figs.

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In July 1999, a tracer-injection study was conducted concurrently with synoptic sampling to generate mass-load profiles in Wightman Fork near the Summitville Mine site. The mine site is located in the San Juan Mountains of southwestern Colorado at an elevation of about 3,500 meters above sea level. Metal loads increased substantially along the 2,815-meter study reach along the boundary of the mine site. Spatial determinations of dissolved aluminum, copper, iron, manganese, and zinc loads were used to identify potential source areas to the stream. Overall, four source areas appeared to contribute most of the specific load at the end of the study reach. One source area was along a 60-meter reach downgradient from the toe of the North Waste Dump that generally corresponded to a region of radial faults. Another source area was a short reach that included inputs from the Summitville Water Treatment Facility and the Pump House Fault. In July 1999, seepage from the Summitville Dam Impoundment was a substantial contributor of metal load at the end of the study reach. Finally, the metal load contributed along a 60-meter reach that included Cropsy Creek is considered a substantial source of metal load to Wightman Fork.


Table of Contents



Purpose and Scope

Description of Study Area

Study Approach

Background Chloride Sampling

Tracer Injection

Synoptic Sampling

Tracer-Injection Results

Synoptic-Sampling Results

Metal Loads

Primary Study Reach

Secondary Study Reach


Selected References


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Water Resources of Colorado

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