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Ending Super-Saturation Will Help Salmon by John McKern Walla Walla Union-Bulletin, April 14, 2019

Recently I made a presentation at Ice Harbor Dam on "Who Killed the Snake River Salmon" to advisors of the Washington state Legislature's Agriculture Subcommittee. Mr. Waddell, a retired U.S. Corps of Engineers executive, was given equal time to advocate breaching the dams. Washington's latest appointee to the Northwest Power Planning and Conservation Council was there, too.

I described the decline of the Columbia River salmon considering Indian fisheries, logging, commercial fishing, mining, agriculture, predation and dams. Sixty-five percent of spring/summer Chinook and 85 percent of fall Chinook habitat was lost in the Snake Basin before the lower Snake River dams were constructed.

I explained how the Marine Mammal Protection Act allowed the resurgence of seals and sea lions, and how the reduction in use of pesticides, most notably DDT, has resulted in the resurgence of predator birds like terns, gulls, cormorants, and white pelicans. I discussed predator fish including native Northern Pike Minnows and introduced bass, walleyes, crappies and catfish.

I explained adult fish ladders that provide over 99 percent survival going upstream. I discussed juvenile bypass systems that divert juvenile salmon away from turbines, juvenile fish transportation, the raised weir developed to provide safe bypass over spillways, and the mass spill program ordered by Judge Simon.

I presented NOAA Fisheries data for Little Goose Dam showing 21 percent of juvenile Chinook passing through unmodified spill bay survived at 95 percent, 44 percent passing through the raised weir at 100 percent, four percent going through turbines at 87 percent, and 44 percent bypassed around turbines at 99 percent. Dam survival was 98.2 percent compared to the required 96 percent under the Biological Opinion.

I showed decline of Columbia River salmon runs since 1865 caused by habitat loss and commercial fishing and the resurgence of the runs since the Corps of Engineers improved fish facilities and dam operations over the past few decades. The highest Snake River runs were since 2000 with the dams in place while the lowest ones were during a two-decade drought from 1977 to 1996.

Mr. Waddell followed with a discussion of how the Snake River salmon were doomed unless the dams were breached.

Asked for two things that could improve Snake River salmon runs, I recommended ending the use of mass spill and using overflow spillways, and for fishery agencies to not operate the river at 120 percent gas super-saturation. I would advocate more fish transportation and power generation taking advantage of higher survival through bypass systems.

Excerpt from 2019 FCRPS Biological Opinion

The available information indicates that supersaturated TDG conditions can cause GBT in adult and juvenile salmonids, resulting in injury and death (Weitkamp and Katz 1980). The proposed flexible spill operation (up to 120 or 125 percent TDG) would increase the exposure of spring migrating juveniles to elevated TDG levels from the tailrace of Lower Granite Dam to at least 35 miles downstream of Bonneville Dam. Individuals from all populations and MPGs would be exposed similarly. Smolts typically migrate at depths which effectively reduce TDG exposure due to pressure compensation mechanisms (Weitkamp et al. 2003). However, the proposed flexible spill operation would likely result in a slight increase in the incidence and severity of GBT symptoms and a very small (not measurable through reach survival studies) increase in mortality.

Adult SR spring/summer Chinook salmon typically migrate between Bonneville and Lower Granite Dam during the period that the flexible spill operation would occur (April through June). Adults also migrate at depths which reduce the effective exposure to TDG through depth compensation mechanisms. The proposed flexible spill operation would likely result in a slight increase in the incidence and severity of GBT symptoms and a very small (not measurable) increase in mortality.

Related Pages:
Supersaturation is Real Trouble for Salmon by John McKern, Walla Walla Union-Bulletin, 12/27/18
Breaching Dams Won't Cool River Water by John McKern, Walla Walla Union Bulletin, 11/8/18
Blaming Snake River Dams for Orca Woes a Hoax by John McKern, Walla Walla Union-Bulletin, 8/14/18
Judge, Court of Appeals Ignored Fish Facts by John McKern, Walla Walla Union-Bulletin, 4/8/18
Ending Super-Saturation Will Help Salmon by John McKern, Walla Walla Union-Bulletin, 10/18/17
View from Idaho on Dam Protection by John McKern, Walla Walla Union-Bulletin, 8/1/17
Yes, Consider All Facts on Dam Breaching by John McKern, Walla Walla Union-Bulletin, 6/30/17
McKern Letter: Salmon Runs by John McKern, Idaho Statesman, 1/2/16
Adult Salmon Survival Past Dams is 99 Percent by John McKern, Walla Walla Union-Bulletin, 3/25/15
Hydropower Not Been Replaced by Wind Power by John McKern, Walla Walla Union-Bulletin, 3/6/15
Environmentalists Try to Muddy Waters About Dredging by John McKern, Walla Walla Union-Bulletin, 12/30/14
Talk of Breaching Snake River Dams a Red Herring by John McKern, Walla Walla Union-Bulletin, 3/21/14
Blaming Dams for Fish Loss is a Hoax by John McKern, Walla Walla Union-Bulletin, 8/23/13
Judge Redden's Replacement Can't Be Worse by John McKern, Walla Walla Union Bulletin, 12/5/11
Science Does Not Support Dam Breaching by John McKern, Walla Walla Union Bulletin, 12/19/11