Why Accept Mass Spill as a Panacea?by John McKern
Columbia Basin Bulletin - December 19, 2003
Your articles concerning spill for fish in the 12/12/2003 CBB raise questions.
Why has the use of mass spill been accepted as a panacea when recent research has shown higher survival through bypass systems and, in some cases, through turbines?
Over the past three or four years, research has shown lower survival rates over spillways than the "accepted 98 percent" at several dams. Studies have also shown turbine and bypass survival rates are often higher than spillway survival, yet no one seems interested in allowing fish to pass through the powerhouses instead of the over spillways. Even with the older data, analysis of system survival from Lower Granite Dam to the estuary showed that mass spill reduced survival of Snake River fish compared with system survival with transport. Some analyses showed that use of mass spill reduced system survival by 15-20 percent making this "management decision" as lethal as the dams or the fish eating birds.
Recent data shows in-river survival at best is only about 60 percent for yearling chinook and much lower (27 percent) in low flow years like 2001. The statement that in-river operations improved survival in 2001 resulting in better subsequent returns from that outmigration seems to be an exaggeration. The statement that transport was emphasized in 2001 is an understatement.
In other Bulletins you reported that over 90 percent of the Snake River yearling chinook were transported in 2001 at 98-plus percent survival. If that were the case, wouldn't high survival of the vast majority of the fish far overshadow even a slight improvement of in-river survival for a small minority of the fish?
I found it amusing that NMFS predicted doom and gloom for the 2001 outmigration until the jacks started coming back in 2002. Then they remembered that the majority of the outmigration had been transported with over 98 percent survival.
These debates about mass spill would be funny if they weren't so much nonsense. If fish must be kept in-river, the new behavioral guidance structure/removable spillway weir technology offers a way to provide higher survival over spillways with a fraction of the flow. If you can get higher survival and provide more water for power generation, why would you cling to a system that costs generation and revenue while providing lower fish survival?
Why haven't the fishery agencies and tribes come to the obvious conclusion that higher fish survival with less spill -- BGS/RSW technology -- would generate more funds for other fish protective measures. Not only would installation of this technology fund itself, it would provide ample funds for other fish improvements and help solve regional energy problems as well.
Analysis of the most recent data shows that dam survival is over 95 percent at most Corps dams without mass spill. With BGS/RSW technology, it could increase to 99 percent. That being the case, why isn't the region firmly behind this solution? Remember, the "science" that supported breaching the dams was based largely on 1973 and 1977 survival data -- when in-river system survival was less than 0.5 percent for yearling chinook. With the improvements made from the 1970s through 2000, in-river survival was 27 percent -- over 50 times higher -- in 2001, a drought year second only to 1977.
With BGS/RSW technology, in-river survival could be over 50 percent even in low flow years and may equal transport survival in good flow years. Then the region could make a legitimate decision between in-river passage and transport.
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