What Improvements Remain for Mainstem Passage?

“Only recently have the advantages of surface bypasses been taken seriously, even though the success of surface spill and surface ice/trash collectors for passing juveniles was established decades ago . . . Return to the historical river at dam sites is not necessary for successfully passing juveniles when surface spill, surface collectors, and selective use of ice and trash sluiceways are management options that use natural fish behavior.” Independent Science Group (1996).25

Before turning to structural improvements at the dams, there is one improvement needed of overriding importance. We need to be able to measure what we are doing, and the best way to do that is to complete the installation of PIT-tag detectors so that we can measure what is going on in the lower half of the river. Such measurements represent the first step toward making any improvements in dam passage, yet fishery agencies advocate dam removal even before accurate measurement of the effects of dams.

Reviewing the upriver PIT-tag studies, the National Research Council concluded that the available data “suggest high priority for mitigation efforts directed at increasing survival at the dam rather than speeding fish through pools”26—if that could even be accomplished. Yet most of the resources devoted to salmon recovery are devoted to flow augmentation, with essentially no effect on survival at the dam. Until we can measure survival in each reach of the river, all of the changes we make are little more than guesswork.

As the Independent Science Group emphasized, there are clear paths to improve “across-the-concrete” survival of fish at dams. Before he became a leading anti-dam radical, Ed Chaney wrote that “fish and hydroelectric energy are not inherently incompatible”. If dams were “properly designed”, he said, “fish passage would divert a small fraction, perhaps one percent, of the average annual flow of the Columbia River”.27

The most promising concept is surface bypass/collection. Juvenile salmon travel in the upper portion of the water column and are attracted to currents at dams. It is just common sense, as the Northwest Power Planning Council’s Independent Science Group recently observed, “to design fish guidance that accomodates the normal behavior of fish rather than attempts to subvert it”.28

Unfortunately, at the dams on the mainstem Columbia and Snake Rivers, the spillway is located some distance along the dam away from the powerhouse. Thus when turbines are operating, the current attracts many fish through them, rather than over spillways (unless the salmon are prevented from going into the turbine with screens).29

However, at Wells Dam on the middle Columbia River in Washington, the spillway is located over the top of the turbines, so that when currents attract the fish, they can pass over the spillway rather than diving through turbines. At Wells, “on average 89% of the smolts that arrive at the dam pass via the vertical slot bypass”.30 The U.S. Army Corps of Engineers believes that surface bypass is at least as effective as the screens, if not more so, and may speed up juvenile passage as well. They think it also provides a “less stressful method of collection”.31

Tests using horizontal slots to limit flows through a sluiceway over the powerhouses at Ice Harbor Dam showed that even using a relatively small amount of flow could attract 53% of the fish through the sluiceway.32 Two researchers at the Oregon Department of Fish and Wildlife calculated indirect estimates of the sluiceway efficiency by estimating the number of fish passing the dam upstream (John Day) and entering from the Deschutes River; they found bypass efficiencies of 78% in 1978, 85% in 1979, 67% in 1980, 68.5% in 1981 (for yearling chinook).33 This is a remarkable result, since flows through the sluiceway were only about 2.5 to 4 thousand cubic feet per second, or 1-2% of the total river flow. Similar, although less effective, results were obtained using the sluiceway at Bonneville Dam.34 The method does not work as well for subyearling chinook salmon, but they are smaller and probably have better turbine survival.

Unfortuately, most of the research has been ignored by the salmon managers. I am told power interests share some of the blame here, because in the early 1980s they opposed giving up the even the relatively small amount of flow required to pass smolts through the sluiceway. Indeed, modifications were made to Bonneville Dam that probably blocked this low-cost way of passing most juveniles away from the turbines through sluiceways.35 But this method of fish passage can be restored, and restored for a tiny fraction of the costs currently spent for salmon recovery.

The Columbia River Alliance has been pushing a transportation and surface bypass/collection strategy for salmon recovery, which it calls Recover 1”, since 1993. The plan is largely ignored, and is never included in media listings of salmon restoration plans. Yet sophisticated computer modeling shows that it would produce the greatest population gains for endangered Snake River salmon among all the competing salmon plans.36

With the exception of their efforts to re-engineer the dams to spill massive quantities of water without creating dissolved gas, harvest managers in the states and tribes resist any spending for structural improvements in survival at the dams. They continue to fight tests of surface collectors, and have succeeded so far in preventing any expansion of the Lower Granite test. When a contractor’s delays in the spring of 1996 forced installation of a test bypass facility in the middle of salmon migration season, triggering extensive spill and gas supersaturation, the states and tribes got an excuse to bash surface bypass. Calling in their political allies Crapo and Furse, they succeeded in holding one of the few oversight hearings in salmon recovery, for the express purpose of discrediting surface bypass.

We need to settle on the surface collector/bypass option. The only place that question can be settled is Congress. But because the public pays little attention to what is going on, Northwest politicians are tending to appease the environmentalists and fishery agency bureaucracies. They and Congress are drifting thoughtlessly toward the “remove the dams” option, propelled in part by biased media reports that label "construction of devices to help fish pass dams safely" as "repeating the failures".37

Ironically, one of the four members of the Columbia River Inter-tribal Fish Commission, the Warm Springs Tribe, is attempting to gain control of the hydropower project on Oregon’s Deschutes River currently operated by Portland General Electric Company.38 If the Tribe's petition before Federal Energy Regulatory Commission succeeds, it will be interesting to see if the Tribe develops a more practical recognition of the compatibility of dams and salmon. Given the decline of critical facilities in media and government, the most likely outcome is that the Tribe would defend its dam and attack the other dams, with no accountability for the inconsistency.

25 ISG, Return to the River 250.

26 NRC, Upstream at 201 (Prepub. ed.).

27 Quoted in J. Cone, A Common Fate 120.

28 ISG, Return to the River 201.

29 See generally “Fish Research: Filling the Gaps”, Salmon Passage Notes, at 1 (USACE NPD Feb. 1996).

30 D. Chapman & A. Giorgi, “Comments on Work of Biological and FCPRS Alternative Work Groups”, at 15 (1994).

31 U.S. Army Corps of Engineers, "Interim Status Report", at ES-15.

32 See “Fish Research: Filling the Gaps”, Salmon Passage Notes, at 1 (USACE NPD Feb. 1996).

33 D. Nichols and B. Ransom, “Development of The Dalles Dam Trash Sluiceway as a Downstream Migrant Bypass System, 1981”, Annual Progress Report, Fish Research Project, Oregon, USACE Contract No. DACW57-78-C-0058, at 28. Results for subyearlings showed only about 40% bypass efficiency.

34 C. Willis & B. Uremovich, “Evaluation of the ice and trash sluiceway at Bonneville Dam as a bypass system for juvenile salmonids, 1981”, Annual Progress Report, Fish Research Project, Oregon, NMFS Contract No. 81-ABC-00173.

35 See “Fish Research: Filling the Gaps”, Salmon Passage Notes, at 1 (USACE NPD Feb. 1996).

36 See J. Anderson, “Comparison of Mainstem Recovery Options Recover-1 and DFOP”, Dec. 13, 1994.

37 J. Brinckman, "$3 billion later, Columbia Basin salmon dwindle", July 27, 1997.

38 Clearing Up, Jan. 13, 1997, at 10.

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