were performed to document the effectiveness of Anaconda 

 Minerals Company's efforts to treat water in Silver Bow 

 Creek. These earlier studies are discussed in the following 

 sections. 



Silver Bow Creek 



Spindler (1959) documented grossly polluted conditions 

 in Silver Bow Creek in 1957. He reported very high levels of 

 copper, iron, and zinc; low dissolved oxygen levels; high 

 turbidity; no pollution-sensitive macroinvertebrate species, 

 and only one tolerant form. 



The first attempt to address the water quality problems 

 in the headwaters had come in 1911 when the Anaconda Copper 

 Company built a treatment pond near Warm Springs to settle 

 out its industrial wastes. Two more treatment ponds were 

 added in 1916 and between 1954 and 1959. With the addition 

 of the third pond, this system became quite effective in 

 settling metals out of the stream. Water quality in the 

 Clark Fork improved below the ponds, as demonstrated by the 

 following data from Spindler (1959) : 



Station 



Silver Bow Creek at 

 Silver Bow 



Metals (ug/1)* 

 Copper Zinc Arsenic 

 11,200 3,350 40 



Silver Bow Creek above 4,200 

 settling ponds 



Clark Fork below 

 settling ponds 



10 



3,660 



400 



30 



trace 



* maximum of two samplings, summer 1957 



However, Silver Bow Creek continued to receive raw 

 mining and milling wastes, and by the mid-1960s, the 

 accumulated solids in the ponds had begun to reduce the pond 

 volume and, hence, the efficiency of the system. The 

 Anaconda Company decided to construct new treatment facili- 

 ties within the Butte Operations to replace the Warm Springs 

 Ponds as the primary wastewater treatment system (Spindler 

 1976) . The new program included lime neutralization, 

 flocculation, co-precipitation, settling, secondary polish- 

 ing, and pH adjustment (Chadwick et al. 1986). 



3-57 



