PUBLIC HEALTH ASSESSMENT
COBALT, LEMHI COUNTY, IDAHO
- The Blackbird Mine site may pose a public health hazard for persons, such as hikers, campers, or site trespassers, who inadvertently drink water from area creeks impacted by site contaminants, including Blackbird, Meadow, Bucktail, South Fork Big Deer, and Big Deer Creeks. These persons could experience gastrointestinal effects as a result of ingesting heavy metals, such as arsenic, cobalt, copper, iron, and zinc, in the creek waters. However, warning signs which have been posted along Blackbird Creek should discourage persons from drinking water from this creek. Exposure to metals in the other contaminated creeks is less likely since these creeks are located in higher, more remote areas of the site and, as a result, are more difficult to access.
- The following site-related exposures are also likely in the past, present, and /or future:
- exposure of former mine employees, previous site investigators, recent on-site remediation workers, forest service personnel, and site trespassers to metals in site surface deposits (e.g., tailings, waste rock).
- exposure of former mine employees, previous site investigators, recent on-site remediation workers, forest service personnel, site trespassers, and users of the national forest (e.g., hikers, fisherman) to metals in area surface waters impacted by the site through skin contact with surface water and sediment.
- exposure of former mine employees, and site workers involved in recent site activities, i.e., construction of the surface diversion channel across the tailings impoundment and associated spillway, to airborne particulates (e.g., tailings, soil) and fugitive dust, especially during activities which generate large amounts of dust (e.g., blasting, drilling, earthmoving, truck traffic).
However, the significance of these exposures is either minimal or cannot be determined from currently available information.
- Heavy metals, including arsenic, cobalt, copper, iron, manganese, nickel, and zinc, continue to be released to area surface waters from acid mine drainage and contaminated runoff from site surface deposits (e.g. tailings and waste rock piles) and from mine adits and groundwater seeps. The discharges of metals have severely impacted the aquatic biota of area creeks including Meadow Creek, Big Deer Creek, Bucktail Creek, Blackbird Creek, and to a lesser extent, Panther Creeks. Since fish are reportedly absent from the Blackbird Creek and Big Deer Creek drainage basins, the potential for human exposure to metals as a result of consuming fish from these two creeks is remote. However, persons who fish Panther Creek below Blackbird Creek or Big Deer Creek could potentially be exposed to heavy metals by eating fish caught in the creek. The significance of this potential exposure pathway cannot be evaluated, however, because sampling data for fish from this creek are unavailable.
- The new diversion channel across the surface of the West Fork Blackbird Creek tailings impoundment should reduce contamination of Blackbird Creek and help prevent a potentially catastrophic failure of the mine tailings dam.
- Data inadequacies include the following:
- Sampling data for the Panther Creek Inn water supply are unavailable.
- No information or data exist regarding potential metals contamination in Panther Creek fish.
- Provide on-site workers with adequate protective equipment and follow appropriate OSHA and NIOSH guidelines, especially during site activities which generate significant quantities of airborne particulates and fugitive dust.
- Ensure that Blackbird Creek remains posted to warn hikers and others visiting the site area of the contaminated surface water.
- If possible, post signs along other contaminated site creeks (i.e., Meadow Creek, Bucktail Creek, South Fork Big Deer Creek, and Big Deer Creek) indicating that they are not safe for drinking.
- Consider sampling the water supply for the Panther Creek Inn to ensure that no site-related contaminants (metals) are present at levels of health concern.
- Consider sampling fish in Panther Creek downstream of Blackbird Creek and downstream of Deer Creek to ensure that fish tissues do not contain metals at unsafe levels.
- Consider implementing activities to reduce metal loadings to site creeks, such as sealing of mine adits, diverting additional adit discharges to the wastewater treatment plant, and redirecting creeks and surface runoff around waste rock piles.
- Continue operation of the wastewater treatment to treat acid discharges from the underground mine workings.
Health Activities Recommendation Panel (HARP) Recommendations
In order, to determine if public health actions are needed, ATSDR's Health Activities Recommendation Panel (HARP) has evaluated the data and information developed in the Blackbird Mine Site Public Health Assessment. Occasional trespassers may access the site and ingest the contaminated surface water in the creeks. This exposure is expected to occur infrequently since the site is remote and current removal activities limit access to trespassers. A drinking water advisory has been posted along Blackbird Creek to warn the occasional trespasser of the risk of drinking the contaminated surface water. There is no current use of the contaminated groundwater as a potable water supply. For these reasons, HARP has determined that no public health actions are indicated at this time.
Public Health Action Plan (PHAP)
The purpose of the Public Health Action Plan (PHAP) is to ensure that this public health assessment not only identifies public health hazards but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. At this time, no public health actions to be implemented have been identified. ATSDR will collaborate with appropriate federal, state, and local agencies to pursue the implementation of the recommendations outlined in this public health assessment. The PHAP will be evaluated annually unless additional information warrants more frequent evaluation.
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
ATSDR Regional Representative:
Senior Regional Representative
EPA Region X
- RCG/Hagler, Bailly, Inc. Blackbird Mine Site Source Investigation Field Sampling Report. April 21, 1993.
- U.S. EPA. Hazard Ranking System Package for Blackbird Mine. May 1993.
- U.S. Forest Service. Preliminary Assessment Site Investigation (revised) Blackbird Cobalt Mine. November 1991.
- U.S. Environmental Protection Agency, Region X. Request for Removal Action at Noranda Mining Inc., Black Bird Mine, Tailings Impoundment, West Fork Blackbird Creek, Lemhi County, Cobalt, Idaho. May 13, 1993 (approved August 6, 1993).
- U.S. Forest Service. Final Aquatic Biology Technical Report for the Blackbird Project. September 1981.
- University of Idaho, Department of Chemistry. Environmental Studies of Arsenic, Cobalt, and Copper in the Blackbird Mining District, Idaho. June 30, 1981.
- U.S. Environmental Protection Agency, Region X. Biological Assessment of the Effects of Constructing an EPA Ordered Diversion Channel on West Fork Creek for Snake River Spring/Summer Chinook Salmon (draft). August 9, 1993.
- U.S. Forest Service. Final Groundwater Hydrology Technical Report for the Blackbird Project. September 1981.
- Ecology and Environment, Inc. Blackbird Mine Site Trip Report. October 18, 1993.
- Ecology and Environment, Inc. Blackbird Mine Site Second Preliminary Trip Report (draft). June 15, 1993.
- U.S. Department of the Interior, Bureau of Land Reclamation. Summary Report of Travel. October 12, 1993.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for arsenic. Atlanta, Georgia: Agency for Toxic Substances and Disease, March, 1989; DHHS publication no. (PHS)TP-88-02.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for chromium. Atlanta, Georgia: Agency for Toxic Substances and Disease, July 1989; DHHS publication no. (PHS)TP-91-19.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for cobalt. Atlanta, Georgia: Agency for Toxic Substances and Disease, July, 1992; DHHS publication no. (PHS)TP-91-10.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for copper. Atlanta, Georgia: Agency for Toxic Substances and Disease, December, 1990; DHHS publication no. (PHS)TP-90-08.
- Toxicology: The Basic science of Poisons. Macmillan Publishing Co. Second Edition. 1980.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for lead. Atlanta, Georgia: Agency for Toxic Substances and Disease, April 1993; DHHS publication no. (PHS)TP-92-12.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for manganese. Atlanta, Georgia: Agency for Toxic Substances and Disease, July, 1992; DHHS publication no. (PHS)TP-91-19.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for nickel. Atlanta, Georgia: Agency for Toxic Substances and Disease, October 1991; Draft.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for zinc. Atlanta, Georgia: Agency for Toxic Substances and Disease, October 1992; Draft.