10 



On the other hand, I see no alternative to spill in the near term. 

 In the long term, the most promising alternatives to spill involve 

 an end to electric power generation and transportation of commod- 

 ities on the lower Snake River, so I think it behooves us to see 

 whether or not we can make spill work. 



The benefits of using spill as a juvenile fish passage mechanism 

 are established for a broad variety of localities. However, each hy- 

 droelectric dam is different, so the actual benefits achieved will de- 

 pend on the design of the hydroelectric facility, the species, the life 

 history type, and ambient physical conditions, among other factors. 



The benefits of spill are established in relation to the passage 

 mechanisms of turbines and bypass in some localities for some spe- 

 cies and life history types. However, the same limitations of time 

 and place apply to these comparisons as described above for the 

 overall benefits of spill as a passage mechanism. • 



Nitrogen supersaturation definitely poses a risk to migrating 

 salmon and the resident species since prolonged exposure to nitro- 

 gen saturation levels above approximately 115 percent at the sur- 

 face has been demonstrated in the laboratory and in net pens to 

 be lethal to fish. The risk may be negligible or serious depending 

 on the degree to which the distribution of the fish coincicfes with 

 the distribution of the nitrogen supersaturated waters. 



To put nitrogen supersaturation into perspective, I do not regard 

 the risk of mortality for salmon, which are actively migrating 

 through nitrogen supersaturated waters to be as serious as the risk 

 posed by migrating through turbines or bypasses for a number of 

 reasons. First, supersaturation drops off sharply with depth. For 

 example, the potential lethal total dissolved gas level of 140 per- 

 cent at the surface is reduced to the still potentially lethal but 

 lower level of about 126 percent just below the surface. 



Second, migrating adult chinook are known to travel closer to the 

 bottom than to the surface of the reservoirs when they have the op- 

 portunity. Third, although juveniles have been observed at all 

 depths in the water column, the majority of juvenile salmon are 

 likely to travel in an average depth of aoout 10 feet according to 

 one study. 



Fourth, if gas bubble trauma is affecting large numbers of juve- 

 niles, I would expect to see much higher rates of symptomatic juve- 

 niles than the negligible rates observed in 1995. Fiftih, althougn the 

 depths occupied by resident fish depend on factors such as feeding 

 and reproductive behavior, monitoring studies have found few resi- 

 dent fish with gas bubble trauma symptoms. 



Sixth, the effects of nitrogen supersaturation on juvenile salmon 

 appear to be reversible since juvenile salmon are frequently re- 

 ported to recover from the effects of exposure to nitrogen 

 supersaturated water. 



In closing, I would like to point out that it is really a stunning 

 indictment of the research system that we've spent so much money 

 and we don't have estimates of survival of juveniles in the hydro- 

 electric system. I would echo the comments of other people who 

 have called for an independent peer review process to guide re- 

 search. I think we do this in all other areas where we spend very 

 large quantities of public money on research. 



Thank you. 



