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Montana 



Groundwater from the different sources has unique water quality charac- 

 teristics as illustrated by Figure 59. Water in the Fox Hills-Hell Creek 

 (Frenchman-Whitemud-Eastend) regional aquifer has characteristics typi- 

 cal of those for the rest of the region. The water has undergone cation 

 exchange and sulfate reduction, leaving very low concentrations of cal- 

 cium, magnesium, and sulfate. The chloride concentrations are higher 

 than those occurring in eastern Montana but are not atypicial for this 

 locale (Montana Groundwater Information Center data, Butte) . Predominant 

 constituents are therefore sodium, chloride, and bicarbonate. 



-*■ wt -«-w1l -»-w5 -e-w6 -*-»t0 



Ug No+K 



Fox Hills-Hell Creek 



Unconsolidated 



Fort Union non-coal 



Figure 59 . --Concentrations of major ions in milliequivalents 

 per liter in water from four major aquifers. 



