Columbia River Salmon Passage Model

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Juvenile salmon must run a hazard-filled obstacle course to pass from the Lower Snake and Columbia rivers to the Pacific Ocean, passing through a series of reservoirs and dams on their way out to sea. In some cases, dams have been equipped with bypasses and screens to divert fish from the clutches of power plant turbines. Fish are trucked or barged around four of the dams and set free below the Bonneville Dam, the last obstacle en route to the Pacific. footnote 1 hyphen footnote 3

The question of how best to save the dwindling salmon runs has been a hotly debated issue in recent years. Some organizations advocate adopting a program of "drawdowns," in which more water is spilled over dams during the spring salmon migration in order to help the fledgling fish survive the journey. Although drawdowns mean less water for use in generating electricity, irrigation, commercial barge traffic, and recreation, advocates believe the benefits of saving the salmon runs offset the costs.

Others contend that drawdowns will reduce, not increase, the salmon survival rate, and that transporting fish is the best way to recover endangered salmon runs. Proponents of that school of thought point to new experimental evidence gathered by John Skalski of the UW School of Fisheries and John Williams and Bob Iwamoto of the National Marine Fisheries Service. Their data suggest that juvenile salmon survival rates in Snake River reservoirs are much higher than previously had been assumed.

Sorting out these issues and making river management decisions for daily as well as long-range planning is an extremely complicated problem that ultimately must take many complex factors into account. Computer modeling tools have been developed over the years in an attempt to evaluate the potential effects of management decisions. The UW School of Fisheries has been a leader in developing quantitative methods for fisheries management, particularly in the use of computer models and the development of statistical methods. Since the late 1980s, scientists at the School have been working on an interactive computer model that allows the power utilities, natural resource managers, researchers, and policy analysts to predict the consequences of interventions, such as spilling water at dams, adding flow from storage reservoirs, drawdowns, or barging fish around dams, on the survival rate of migrating salmon.

UW fisheries scientist JamesJ. Anderson, leading a 20-person research team, has developed a computer model of salmon passage through the Columbia River Basin, known as the CRiSP model.footnote 4 The model can be used to predict how many fish could make it through the system to the Pacific based on hatchery release dates, reservoir levels, water flow rates, and other factors. The computer tool calculates the effects of these influences rapidly and displays the results using color graphics. On a daily basis, these predictions, plus information on fish movements and river conditions, are made available to the public through the World Wide Web. These tools were developed at, and are maintained by, the UW's Center for Quantitative Science (CQS) under contracts with the Bonneville Power Administration.

The CRiSP model presents a sophisticated and distinctly different analysis compared to existing salmon passage models developed by the Northwest Power Planning Council and by the Columbia Basin Fish and Wildlife Authority, a coalition of federal and state fish agencies and Columbia Basin tribes. Anderson hopes that a comparison of these modeling efforts will generate hypotheses about salmon survival rates that can be tested in further experimental work in the future to assist managers in making the best decisions possible about how to save our endangered salmon runs. Anderson has been a pioneer in bringing fisheries management tools to the Web. The information placed there by CQS is being used daily by public and private organizations, and even by high school science classes.

  1. "Flowing Pains," Sandra Hines, Columns, December, 1994, p. 20.
  2. "Dueling science: Debate over drawdowns," Steve Meyers, East Oregonian, Jan. 28, 1995.
  3. "Diverting Migrating Fish Past Turbines," J. J. Anderson, The Northwest Environmental Journal, 4, 109 (1988).
  4. Columbia River Salmon Passage Model Manual, UW School of Fisheries Special Publication, 1994.

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