Watershed Contamination from Hard Rock Mining Completed

The approach was to study chemical processes within a hydrologic context, using a two-step approach:

• First, the USGS used instream experimentation to provide data about the processes affecting metals.
• Second, the USGS used the resulting data sets to develop and apply solute transport models to help quantify rates and processes.

Tracer-injection studies in St. Kevin Gulch, near Leadville, Colorado, helped the USGS design methods to characterize loading from mining activities on a watershed scale. Tracer-injection studies were done in 1995, in support of the planning needs of Federal Land Management Agencies, and as part of the USGS Abandoned Mine Land Initiative.

OBJECTIVES:

1. To characterize the instream chemical processes that control the transport and transformation of metals downstream from mine drainage.
2. To use tracer-injection methods to evaluate remediation efforts in selected basins.
3. To quantify the time and length scales of chemical and hydrologic processes that affect the metals through development of solute-transport models.
4. To characterize the chemistry of colloids, sediment, and bed sediments that are active in controlling the dissolved concentrations of metals.