102 



' bine outages, and a hieher-than-anticipated runofiF event at the foiir lower Snake 

 River projects combined to raise total dissolved gas levels above the state standards. 

 In this case, even though Federal Managers could do little about the causes of the 

 situation, a number of operational changes were made to reduce the impacts of the 

 involuntary spill. 



The options that have been pursued to date to control dissolved gas levels in the 

 river system include: (1) filling Snake River reservoirs in a short-term effort to re- 

 duce spill; (2) distributing spill at Snake River dams above Ice Harbor over 24 

 hours, instead of 12 hours, to reduce instantaneous spill by 50 percent; (3) running 

 turbine units at the lower three Snake River projects outside of peak (within one 

 percent) efficiency to reduce water being spilled; (4) adjusting the spill pattern at 

 Ice Harbor Dam. (i.e., spilling the same volume, but distributing it among spillways 

 in a different manner) to reduce total dissolved gas levels; and (5) reoucing spill 

 below levels authorized in the FCRPS biological opinion at three lower Snake River 

 dams to reduce cumulative total dissolved gas effects. Some of these measures mav 

 have some negative effects on juvenile survival (e.g., running turbines outside peak 

 efficiency, reducing spill at Lower Granite Dam, and filling reservoirs), but the 

 NMFS and the Corps are agreed that it is important to take all reasonable steps 

 to comply with the state water quality standards. 



SPILL AND RESroENT FISH 



NMFS is attentive to the fact that increased flows for salmon may affect resident 

 fish. Augmentation flows affect resident fish both in the reservoirs and in tiie river 

 reaches below them. The Idaho Department of Fish and Game (IDFCJ) offered testi- 

 mony about impacts on resident fish at a May 10, 1995, hearing. They perform bio- 

 logical monitoring in the Clearwater River, and during the hearing they commented 

 on spill at Dworsnak Dam and total dissolved gas levels in the river below the dam. 

 The impact of reservoir drawdown on kokanee and black bass populations in the 

 reservoir was of particular concern to the citizens at the hearing. The district IDFG- 

 biologist for the Lewiston/Orofino area testified that kokanee populations are in 

 very good shape and have increased since the reservoir operation was changed fi-om 

 draiting in the winter (for power production) to drafting in the summer (for fish 

 flows). He also indicated that the decrease in black bass populations is primarily 

 due to lower populations of forage fish, primarily redside smners, and not due to 

 loss of shoreline spawning habitat fi"om reservoir drawdown. 



Augmentation flows that result in spill can affect resident species in two ways: 

 By entraining and passing residents into the river below; and, if spill volume is high 

 enough, by raising total dissolved gas levels in the river below the dam. In the case 

 of Dworshak Reservoir and Dam, kokanee is the primary (and perhaps the only) 

 species that is entrained. While tiiis can have detrimental effects on the entrained 

 individuals, there is no evidence that the kokanee population in the reservoir has 

 been adversely affected. 



During the past 3 years, while spill was occurring, the health of resident species 

 has been momtored at several locations. The results to date indicate that resident 

 species exhibit very littie, if any, sign of gas bubble trauma when exposed to total 

 dissolved gas levels generated by voluntary spill. IDFG is monitoring the health of 

 resident fish in the North Fork and main Clearwater River below Dworshak dam. 

 Spill would be reduced at the dam if monitoring indicated that serious impacts on 

 resident fish. A very low prevalence of gas bubble trauma signs was noted in resi- 

 dent species during the spring 1995 spill at Dworshak Dam. 



CONCLUSION 



The 1995 spill program reflects the vears of study and evaluation that were the 

 basis for NMFS' Proposed Recovery plan for Snake River Salmon. It has brought 

 Federal managers together in a spirit of cooperation to optimize operation of the 

 Federal Columoia River Power System. At the end of the operating season, NMFS 

 and other fisheries managers will perform a thorough evaluation of the lessons 

 learned by reviewing the results of the operational decisions recommended by the 

 TMT, ansuyzing the data fi-om the gas monitoring program, and examining the re- 

 sults of the numerous research projects. The information derived fi"om this adaptive 

 management process will help resolve questions about alternative ways to improve 

 the survival oi migrating salmon. 



In closing, I would like to emphasize several points: 



First, NMFS has decided to employ a managed voluntary spill program as one of 

 the few existing tools to achieve unproved fish guidance around individual projects, 

 and that improved in-river migrations are part and parcel of the larger effort to im- 

 prove fish survivals in the system. 



