Guich. There is also some geologic evidence of historic iron staining in the canyon, so 

 there may be a natural component to the some of the contamination. '' The water 

 quality situation in Swift Gulch is acknowledged by the agencies to be an issue that 

 requires further study and analysis. 



Swift Gulch Drainage, 2001. BLM Photo. 



Pegasus partially backfilled the north end of the Landusky pit in 1995-1996 with rock 

 that produced low pH acid. In 2002, the DEQ attempted to further isolate the area 

 with additional nonacid-producing rock backfill, which was then covered with an 

 impermeable barrier in an effort to limit the infiltration of precipitation to the area, 

 including infiltration through the sheer zone. It was not anticipated that this effort 

 would produce any immediate positive results if, in fact, this was the source of the 

 contaminated water that was appearing in the seeps along the upper reaches of Swift 

 Gulch. To date, the situation has not improved. There are several monitoring sites 

 along Swift Gulch and the South Fork of Bighorn Creek that are monitored routinely. 

 Although Swift Gulch is clearly impacted, as yet there have been no exceedences of 

 the Consent Decree or draft MPDES water quality limits at the reservation boundary 

 monitoring site designated as L-48.^° 



11 



