231 



DRAFT 



The report should make the distinction that the cited turbine efficiencies (90-92%) are 

 those modeled by manufacturers and that none of the turbines at mainstem dams have 

 been indexed in-situ. Furthermore, it is unknown to what extent turbines are operated 

 at peak efficiency. Monitoring of turbine operations at Corps projects in 1992 indicates 

 that turbines are frequently operated outside of 1 % of peak efficiency (operating 

 criteria established by the agencies and tribes) especially during low flow periods. 



'Today, most researchers use the Schoeneman et at. , (1961) 11 perceru 

 mortality rate as the best available mortality estimate for typical vertical 

 Kaplan turbines. " 



This statement is false. In the Columbia and Snake basins, most researchers use a 15% 

 turbine mortality rate, not the 11% estimated by Schoeneman et al. for McNary Dam. 

 The NPPC used a 15% turbine mortality in System Planning (Integrated System Plan, 

 CBFWA 1990) which is the mid-point of turbine mortality estimates of Columbia River 

 dams (11-20%). 



'Preliminary screen assessment studies indicate that screening 

 mortalities may be similar to turbine mortality. " 



This statement is incorrect and obviously based on a single study, the Bonneville II 

 survival study that showed that mortality of fish passing through the bypass system was 

 higher than fish passing through turbines. The Bonneville II survival study is 

 incomplete (adult returns will not be complete until 1995), and results from this study 

 are not applicable to other dams due to design problems of the bypass system, location 

 xjf the bypass outfall in an area of high predator abundance, and high efficiency of 

 turbines (92% compared to 90% or less at other Corps projects). 



Page 63, 2.1.8. Modified Habitat Issues 



'In arty event, transportation survival is relatively high (80-90%) in 

 contrast to river migration past and through several water use project. " 



This statement should be qualified. It is true that transportation survival of smolts is 

 relatively high compared to in-river migrants. However, transportation survival to 

 adult compared to in-river migration has been shown to be higher for steelhead at 

 Corps projects but marginally higher for chinook. At mid-Columbia projects, 

 transportation survival of chinook and sockeye to adult has been shown to be lower 

 than in-river migration (Carlson et. al. 1989). 



'Gas supersaturanon levels have subsequently decreased, but at higher 

 spill levels they can still cause significant smolt mortalities (NPPC, 

 1986, FPC, 1991). ' 



Although a Fish Passage Center 1991 report is cited as supporting this statement, close 

 review of the FPC report reveals that it is being misinterpreted here. The FPC report 



A-25 



