184 WARD, CANTON, AND GRAY 



TABLE 3 



IONIC COMPOSITION (mg/liter), 



SPECIFIC CONDUCTANCE, AND 



pH OF EDNA MINE SPOILS 



* Saturated paste analyses (MeWhorter, 

 Skogerboe, and Skogerboe, 1975). 



of most western streams would require major inputs of acid or base 

 to change the solubilities of most metals appreciably. In addition, 

 Cairns (1976) stressed that hard, well-buffered waters reduce the 

 adverse effects to biota of many toxic materials. 



There is some evidence that many elements contained in the 

 mine spoils do not reach Trout Creek in large quantities. Sediment 

 from runoff channels in the mine contained higher concentrations of 

 all heavy metals analyzed, except mercury, than did sediment from 

 Trout Creek (Skogerboe, 1976); this "implies that those elements 

 contained in the runoff are largely removed from solution, perhaps 

 by precipitation, before the runoff reaches the creek." The presence 

 of a strip of unmined land between the mine spoils and the creek 

 may considerably reduce the input of potentially toxic substances to 

 the stream. 



Soluble salts from the overburden are considered by some to be 

 the most significant potential pollutant of streams from strip mines in 

 the West (MeWhorter, Skogerboe, and Skogerboe, 1975). Edna Mine 

 spoils contain large amounts of certain ions (Table 3). Precipitation 

 in more mesic regions is sufficient to leach out soluble salts as they 

 form, but, in the arid and semiarid regions of the western United 

 States, only the top few centimeters of soil are adequately leached. 

 Surface mining exposes fresh surfaces and increases leaching of 

 soluble salts; this results in an approximate doubling of total 



