THIS UNILATERAL ADMINSTRATIVE ORDER DIRECTS THE RESPONDENT TO PERFORM A REMEDIAL DESIGN. SMELTERS, CONCENTRATORS, MILLS, AND ASSOCIATED OPERATIONS PROCESSED HUNDREDS OF TONS OF ORE EACH DAY AND DISPOSED OF LARGE QUANTITIES OF TAILINGS, SLIMES AND OTHER WASTES DI- RECTLY INTO AND ALONGSIDE SILVER BOW CREEK. IN ADDITION, THE ANACONDA COPPER MINING CO. DISCHARGED HEAVILY CONCEN- TRATED MINE WASTES THROUGHOUT THE AREA. WASTE PILES FROM THESE MINES ALSO CONTRIBUTED, THROUGH RUN-OFF, TO THE CON- TAMINATION OF SILVER BOW CREEK. ENVIRONMENTAL AGENCIES CONDUCTED A RISK ASSESSMENT EVAL- UATION FOR BOTH HUMAN AND ECOLOGICAL RISK FACTORS. THIS RE- PORT WAS RELEASED ON 12/29/94. THE RISK ASSESSMENT EVALU- ATED FOR ON-SITE RESIDENTS AND RECREATIONISTS IDENTIFIED PO- TENTIAL CANCER RISKS GREATER THAN 1 IN 10,000---THE RISKS BEING IDENTIFIED AS EXPOSURE TO GROUNDWATER, SOILS AND RAIL- ROAD MATERIALS CONTAMINATED WITH EXCESSIVE AMOUNTS OF LEAD, COPPER, ARSENIC, CADMIUM, ZINC AND MERCURY. THE ECOLOGICAL RISK IS ALREADY APPARENT IN SILVER BOW CREEK. CONTAMINATION HAS CAUSED THE CREEK TO BE DEVOID OF FISH AND VARIOUS AQUATIC LIFE FORMS.