Physical. Determinations 



Temperature . Air and water temperatures were determined with 

 the use of a 5-1/2 inch mercury-filled thermometer graduated in degrees 

 Fahrenheit and recorded to the nearest degree. Air temperatures were 

 taken in the shade one or two feet above the water surface, holding the 

 thermometer at least two feet away from any object. Water temperatures 

 were determined by immersing the bulb in the stream until the mercury 

 colvmin exhibited no movement. 



Temperatures of bottom waters or waters in the gravels were 

 obtained immediately from 300-milliliter sample bottles. 



Dissolved Oxygen . Dissolved oxygen determinations were made, 

 vising the Alsterberg (azide) modification of the Winkler method. Water 

 was collected by means of a 2-liter Kemmerer water sampler at most sta- 

 tions. S\irface dissolved oxygen saniples were taken at approximately one- 

 to two-foot depths. Bottom dissolved oxygen samples were taken from as 

 near the bottom as possible. At sandy or gravel bottoms, the sampler 

 was allowed to touch bottom, then the messenger released to trip the valves. 

 Over mud or silt bottoms, samples were taken from about one foot off the 

 bottom to eliminate collecting bottom material. 



Water samples were collected by a different method at the stations 

 between mile 29^ and mile 229-8 where sampling was done in shallow water 

 (one to two feet deep) . Water was drawn into a 300-mllliliter bottle 

 by evacuating air from the bottle with a tube, causing a partial vacuum 

 and pxilling water into the bottle through another tube. Samples at these 

 stations were taken at a depth of one inch from the surface, within one 

 inch of the bottom, and, when possible, at a depth of 12 inches in the 



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