The cause of the issuance was the discharge of manganese and sulfate that are leaching from backfill materials to a nearby creek through groundwater flow.

  • The South Dakota Department of Environment and Natural Resources (DENR) issued a notice of violation and order for compliance to a gold mine for violation of the South Dakota Water Pollution Control Act (notice of violation, dated September 5, 1998, South Dakota DENR). The mine was found to be discharging effluent into streams in excess of permit levels for cadmium, copper, zinc, and total suspended solids, and its discharge failed a portion of the acute whole effluent toxicity test. Permit levels were exceeded once in 1996, twice in 1997, and nine times in 1998. In addition, the company failed to conduct daily monitoring of its effluent after the June 1998 violations and failed to promptly send samples for analysis, resulting in exceedance of holding times, both of which also constituted violations of its permit.

As discussed above, these examples are not necessarily representative of environmental impacts at all modem mines, but they do indicate that environmental impacts from some hardrock mining operations continue to exist under current regulatory conditions. However, the full extent of environmental problems at modern mine sites will not be known until better information on hardrock mine sites is collected and analyzed, as discussed in Chapter 3.

The Committee addresses the issue of mining-related impacts by presenting a discussion of the environmental impacts that have occurred, and that may still occur in some cases, even with regulations in place. It must be emphasized that these potential impacts will not necessarily occur, and when they do, they will not occur with the same intensity in all cases. Many of the impacts discussed in this appendix would violate current regulatory requirements and standards and would be subject to enforcement actions. Nevertheless, because some impacts continue, an understanding of the potential for mining to cause environmental impacts is essential to assessing and improving the regulation of hardrock mining on Federal lands.

CUMULATIVE EFFECTS

The environmental impacts of a single mining operation are broadly proportional to the size of the mine, although these vary depending on:

  • the character of the mineral body and surrounding rock;

  • the character of the environment directly and indirectly affected by mining;



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