The National Marine Fisheries Service (NMFS) requires that Columbia river dam operators in the US spill large volumes of water so that juvenile salmon have a higher chance of survival over spillways and through turbines. But according to John McKern – a fish biologist who has recently retired from the US Army Corps of Engineers where he was chief of fisheries management – the NMFS’ own studies show no fishery benefits whatsoever from the spill programme.

McKern says that an analysis of existing scientific information shows that reducing spill will not reduce fish survival.

Mckern claims that it is not a case of spill or kill. He says that reducing spill and maximising transportation actually increase fish survival and that fish agencies have never conducted a comprehensive analysis on the adverse effects of spill on returning adults, even though high spill levels are known to interfere with adult migration and cause excessive levels of dissolved gas in the water that decrease adult survival to spawning. Environmentalists also claim that these high levels of dissolved gas violate the federal Clean Water Act standards.

McKern says that from the 1970s to 1994, reducing spill and maximising transportation increased salmon survival and allowed the runs to be maintained while major improvements were being made to fish bypass systems and dam operations. He says that the use of these protective measures should be maximised in 2001 and believes that if more fish are collected and transported, survival this year could be substantially higher than it was in 2000.