Asking the pikas politely…
The U.S. Forest Service (USFS) and the Colorado Geological Survey (CGS) are continuing a cooperative agreement to identify sites of environmental degradation associated with abandoned and inactive mines on Colorado’s USFS administered lands. The USFS Abandoned Mine Land inventory Project is a “discovery” process and is a precursor to the Environmental Protection Agency’s “Preliminary Assessment” process. identification of environmentally degraded sites may lead to a formal Preliminary Assessment. The inventory process begins in the office and involves reviewing existing mining and geologic literature, previous mine inventory work, current and historical maps, water quality information, and aerial photographs. During field investigation, each mine feature is given a unique identification number. Field geologists collect data on the physical and geographic characteristics of the mine features along with information on any water emanating from or interacting with the mine features. This information is used to assign a qualitative environmental degradation rating to the individual mine feature. Guidelines for the rating system are given to field personnel to facilitate consistency within the data set. All data collected are entered into a computer database. From a computer perspective, both location and attribute data are being collected. Therefore, the data are well suited for integration into a geographic information system (GIS) creating a geo-referenced data set. The USFS Abandoned Mine Land Inventory Project began in 1991 and is ongoing. To date, field inventories of the Arapaho, Roosevelt, Pike, and Rio Grande National Forests have been completed. Work in the San Isabel, San Juan, White River, Gunnison, Uncompahgre, and Grand Mesa National Forests is in progress. Through the 1994 field season approximately 9,667 mine features (openings, dumps, tailings, highwalls, etc.) have been inventoried. In the course of field investigations, evidence of naturally occuring water quality degradation has been found in various parts of the state. The geology and hydrology of these areas are conducive to producing waters from springs and seeps with relatively high concentrations of metals and low pH. These areas usually exhibit hydrothermal alteration of the country rock in addition to vein mineralization. Many of these occurrences are in, or associated with, volcanic terranes. However, some occurrences are known in areas of metamorphic, sedimentary, and igneous terranes. As inventoried mine sites exhibiting environmental degradation progress from identification to site characterization and remediation, it will be important to clearly identify the goals of remediation. Sites that occur in areas of naturally degraded water should, if possible, have background conditions characterized in addition to mine site characterization. Remediation goals for minecontaminated waters can then be set at realistic levels.
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