BFSOU CONSISTS OF FORMER/ACTIVE MINING, MILLING, SMELTING AND RELATED FACILITIES, ASSOCIATED WASTE ROCK & MILL TAIL- ING WASTES. A NETWORK OF RAILROAD TRACKS, SPURS, & STORM WATER DRAINAGES CONSTRUCTED OR CONTAMINATED WITH MINING RELATED WASTES; & ASSOCIATED CONTAMINANTED SOILS IN BUTTE AND WALKERVILLE MONTANA. RESPONDENT IS A PRIOR OWNER AND OPERATOR OF THE FORMER/ ACTIVE MINE FACILITIES. CONTAMINANTS INCLUDE, BUT NOT LIMI- TED TO ARSENIC, ALUMINUM, CADMIUM, COPPER, IRON, LEAD, SIL- VER AND ZINC. THE POTENTIAL HEALTH THREAT TO THE RESIDENTS IN THE BPSOU CONSISTS PRIMARILY OF INGESTION AND/OR INHALATION OF LEAD. THE POTENTIAL ENVIRONMENTAL THREAT CONSISTS PRIMARILY OF COPPER, ZINC, ARSENIC AND OTHER HEAVY METALS. SEVERE ILL- NESSES OR DEATH CAN RESULT TO HUMANS, LIVESTORK AND WILD LIFE FROM THE EXPOSURE TO TOXIC LEVELS OF LEAD AND OTHER HEAVY METALS.