Table 1. — Locations and dales of sampling in the Columbia and Snake Rivers; sampling sites are shown by number in figure 1 



6-390V2 - was substituted for tlieir Model 25, and 

 the length of the extraction chamber was increased 

 to 150 mm. Model G-390V2 is more sensitive than 

 Model 25, and the longer extraction chamber 

 allowed analysis of larger samples. 



Saturation values quoted in this report are cor- 

 rect to within ±2 percent. Limitations in the 

 accuracy of the method and the uncertainty of the 

 theoretical solubilities of nitrogen precluded more 

 precise interpretation. 



- Trade nanii's referred to in this publication do not Inipl.v 

 iMidorsement of coninier<'i;il products by the Unreau of Com- 

 iiiercinl Fisheries. 



EFFECT OF DAMS AND RESERVOIRS ON 

 SATURATION OF DISSOLVED NITROGEN 



Major causes of supersaturation of water with 

 gases are heavy concentrations of algae (Wood- 

 bury, 19i2), warming of water without adequate 

 circulation and exposure to the atmosphere for 

 equilibration, and falling of water into an en- 

 closed plunge basin (Harvey and Cooper, 1962). 

 Algae concentrations like those described by 

 Woodbury are not found in the Columbia River 

 and the river is not warmed sufficiently at any 

 location to account for the high concentrations 

 previously recorded. Spillways at dams create 



SUPERSATURATION OF NITROGEN IN COLUMBIA RIVER 



