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Protecting Endangered Fish is Not 'Radical Environmentalism' by Richard Scully Lewiston Tribune, February 1, 2022

With the lower Snake River dams in place, fishery managers
have continually searched for means to increase smolt survival.

Snake River salmon and steelhead, for thousands of years, have provided social, economic and ecological benefits. It is paramount that the short-term technology associated with the soon-to-be-obsolete lower Snake River dams does not extinguish these essential resources that belong to us and to all future generations.

To recover these dwindling resources, Rep. Mike Simpson proposed that the dams be breached and that those who benefit from the dams be made whole with alternate means. Oregon Gov. Kate Brown and 57 Northwest tribes support Simpson's initiative. Washington Gov. Jay Inslee and U.S. Sen. Patty Murray are currently studying the feasibility of restoring the lower Snake River. These respected leaders are not "radical environmentalists."

They want to protect our highly valued natural resources.

Prior to construction of the four lower Snake River dams in the 1960s, for every 100 juvenile salmon and steelhead that migrated from the Snake River to the ocean, an average of 4% returned as adults. This smolt-to-adult return supported healthy tribal and sport fisheries, and there were sufficient natural spawners to perpetuate the runs. Since completion of the four dams, smolt-to-adult returns for wild Snake River spring/summer chinook and steelhead have declined to 0.7% and 1.6%, respectively, leading toward extinction.

The John Day River, which is downriver from the lower Snake River dams, has spring chinook smolt-to-adult returns that have remained unchanged at nearly 4%. The John Day River chinook survival is determined by trapping smolts in the John Day River, inserting passive integrated transponder tags and then recording the number of PIT tags that return in adult fish at John Day Dam and at PIT tag detectors in the John Day River.

With the lower Snake River dams in place, fishery managers have continually searched for means to increase smolt survival. During the 1980s, emphasis was placed on capturing smolts at the upper dams and transporting them in barges to below Bonneville Dam.

By the 1990s, smolt-to-adult returns were so poor that all Snake River salmon and steelhead were listed under the Endangered Species Act. The 1998 report, "Plan for Analyzing and Testing Hypothesis," determined that barging smolts could not compensate for the negative impacts of the hydropower system. To recover Snake River salmon, a "normative" river would be required; that is, the lower Snake River series of dams and reservoirs would need to become a river again. The Idaho Fish and Game Commission endorsed these conclusions in its 1998 report, "Idaho's Anadromous Fish Stocks: Their Status and Recovery Options."

Since then, a series of comparative survival studies have determined that with the dams in place, better smolt survival occurs when smolts pass over dam spillways and not through high pressure bypass systems, where they are either directed into barges or passed back into the river below the dams. The results of the comparative survival studies were accepted by the Columbia River System Operations agencies and incorporated into the 2020 environmental impact statement. The option that minimized spill and maximized barging, designated as MO2, had the lowest smolt-to-adult returns. The option with the second-best smolt-to-adult returns, designated MO4, maximized spill. And the option with the very best smolt-to-adult returns, designated MO3, and that actually would lead to recovery of Snake River salmon included breaching the dams.

A 2020 Army Corps of Engineers report titled "Fish Passage Through the Lower Snake and Columbia Rivers" stated: "Research has shown that transporting juvenile fish can provide the highest rate of adult returns compared to in-river migrants."

Comparative survival studies also have shown that smolt-to-adult returns can be higher for barging than in-river smolt migration, but only when spring time flows are low (and thus slow), such as in 1977, 2001 and possibly in 2021. However, when spring time flows are average or better than average, survival of in-river migrating smolts will be higher than survival of barged smolts.

In low flow years, smolt survival will be poor, whether barged or left in-river. Thus, if barging had been maximized in 2021, smolt-to-adult returns might be slightly higher than they actually will be, but they still would be inadequate, at least as far as the influence of the smolt migration on smolt-to-adult returns.

The three major factors influencing smolt-to-adults are water transit time (smolt survival increases with faster moving water), number of dam bypass system events (9% to 13% decrease in survival each time a smolt enters a bypass system) and ocean conditions. Low flow years such as 2021 have increased transit time and thus decreased smolt survival.

The National Oceanic and Atmospheric Administration recently reported that 80% of ocean quality indicators were positive for salmon in 2021. Chinook and coho stocks up and down the coast benefited. This fall, there should be good returns of coho, one-ocean steelhead and chinook jacks, all of which arrived at the estuary as smolts in the spring of 2021. However, I believe there will be much uncertainty about the fall returns of Snake River stocks. Was the survival so poor for out-migrating smolts that, even with good ocean survival of the remaining smolts, very few adults will return?

Marvin F. Dugger has stated in his columns that barging smolts is superior to leaving smolts in-river because some large adult returns in recent years were the result of barging most of the smolts.

He uses as an example 2001, when 185,695 spring/summer chinook adults returned above Lower Granite Dam following the 1999 smolt out-migration, when 86% of smolts were barged.

Dugger failed to note that the lowest adult returns above Lower Granite Dam also occurred following equally high barging percentages. In 1992, 1993 and 1994, the proportion of smolts barged were 58%, 89% and 86% and the resulting adult returns were the lowest of the entire data set, which were 3,915 in 1994, 1,797 in 1995 and 6,814 in 1996.

Obviously factors other than barging had larger effects on these adult returns and the same was true for the 2001 chinook return. To consistently have high Snake River salmon and steelhead returns, and rebuild those runs, the lower Snake River dams must be breached.