collected from the southern side of the lake, had a field pH in 

 excess of 9.0, as did all four sites in the 1993 DHES survey of 

 Medicine Lake field chemistry. The 1990 sample, with a 

 substantially higher dissolved solids concentration, had a lower 

 absolute concentration of calcium than the WET49 sample, suggesting 

 the process of atmospheric equilibration and consequent calcium 

 carbonate precipitation characteristic of many lakes linked to the 

 Clear Lake aquifer is ongoing in Medicine Lake. The WET49 sample, 

 collected at the eastern (upgradient) end of the lake, appears to 

 have consisted largely of ground-water discharge not yet 

 equilibrated with the surface environment. Samples collected from 

 the WET49 site should not be expected to represent the chemical 

 characteristics of the main Medicine Lake basin. 



Historically, Medicine Lake is reported to have been essentially 

 dewatered during the extended drought of the 1930 's, stimulating 

 the construction of the diversions and control structures now used 

 for water management. Under naturally fluctuating conditions, 

 water chemistry, as well as shoreline position and water depth, was 

 probably more transient than now, and average salinity likely was 

 higher prior to the import of Big Muddy Creek runoff. 



Sediments. Arsenic and boron concentrations in the WET49 sample 

 were near the upper end of the ranges shown for this 

 classification, and the selenium concentration reported for this 

 site was the highest in it's class. Iron, nickel, vanadium and 

 zinc concentrations ranked mid-range within the site 

 classification; most other trace elements occurred at 

 concentrations below their reporting limits. 



