31 



3.3.3.2 Montana 



Samples were collected from monitoring wells 7, 16, and 24 during 2000. Well 7 is completed in Hart 

 Coal, well 16 is completed in the Fort Union Formation, and well 24 is completed in alluvium. No 

 significant changes in TDS were observed in monitoring wells 7 and 16. The TDS in the alluvium (well 

 24), however, increased about 100 mg/L during the years 1996 through 1998, but has decreased about 

 90 mg/L during 1999 and 2000 approaching the pre- 1996 values. Changes in total dissolved solids with 

 time for the above wells are shown in Figure 3.18. 



Total Dissolved Solids 



-GWQQC16 



Jan-80 Jan-82 Jan-84 Jan-B6 Jan-88 Jan-90 Jan-92 Jan-94 Jan-96 Jan-9e Jan-00 Jan-( 



Date 



Figure 3.18 Total Dissolved Solids in Samples from Montana Wells. 



