RESULTS AND DISCUSSION 



POST-MINING EFFECTS OF GRAVEL REMOVAL OPERATIONS 



General Water Quality Conditions 



Temperature, dissolved oxygen, specific conductance, turbidity, suspend- 

 ed solids, oxidation-reduction potential lORP), and pH were measured up- 

 stream, downstream, and within the gravel removal area at most sites. 

 Measurements were taken in conjunction with the aquatic biological surveys. 

 Temperature, specific conductance, turbidity, and suspended solids values 

 varied substantially among the different sites. However, dissolved oxygen, 

 ORP, and pH values were relatively similar at all sites. The parameter 

 values measured at each study site were compared to the Alaska Water Quality 

 Standards (Table 55). The water quality standards were established to pro- 

 tect various beneficial uses of receiving waters. The most important bene- 

 ficial uses associated with arctic and subarctic streams include water 

 supply, aquatic life, and recreation. At the 25 study sites, aquatic life 

 was the most common beneficial use being supported. Alaska does not have a 

 water quality standard for suspended solids, but a value of approximately 80 

 mg/i suspended solids is usually considered potentially hazardous for 

 aquatic life. Waters containing 25-80 rng/H suspended solids have been shown 

 to have a lower yield of fish than water with less than 25 mg/S, (National 

 Academy of Sciences 1973). 



Water quality standards were exceeded for turbidity, and suspended 

 solids at a few river sites (Table 36) while temperature, dissolved oxygen, 

 specific conductance, and pH criteria were not exceeded. The high suspended 

 solids value at Phelan Creek was due to the glacial origin of the creek; the 



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