ammonium was below reporting limits. The orthophosphate 

 concentration was toward the lower end of the range shown by sites 

 in this classification. Total phosphorous and total organic carbon 

 analyses were not conducted on this sample. 



Copper and zinc concentrations ranked mid-range among sites of the 

 intermontane valleys, exceeded mainly at other mine-impacted sites. 

 Iron and aluminum concentrations were not analyzed for this sample, 

 and other trace element concentrations were below reporting limits. 



Chemical history. No other comparable chemical analyses are known 

 for this site. Generally, increased concentrations of toxic metals 

 have been observed at times of runoff and high flows in the Silver 

 Bow/Mill Creek system as sediment deposits contaminated with 

 mineral processing waste are remobilized. 



Sediments. Exceptionally high concentrations of extractable 

 arsenic, copper, lead and zinc are matched only by other sites with 

 known mine or mineral processing impacts. Iron, chromium, nickel 

 and vanadium concentrations are also relatively high in comparison 

 to similarly classified sites. Arsenic, copper, lead and zinc 

 concentrations far exceed mean soil concentrations for the western 

 United States; other trace element concentrations are below their 

 respective mean soil values. 



