Dams already a model of fish recovery success

By Joe Bippert

After years of study and millions of dollars spent, a draft federal environment impact statement (EIS) on hydroelectric dam operations in the Columbia Basin is being debated. Public comments addressing the draft will be received until April 13.

The latest iteration is the sixth time federal agencies have attempted to come up with an operations plan that meets the requirements of the Endangered Species Act to protect salmon, first listed in the early 1990s. Each plan has been met with litigation from groups that want to remove dams. With comments emerging from pro-breacher community that the current report is “wholly inadequate” and “the same meal with more garnish,” it is expected the same litany of lawsuits will be forthcoming when the report is finalized in September.

The authors of the report, which included staff from the Corps of Engineers, the Bonneville Power Administration and the Bureau of Reclamation, expect as much. Far from resolving the issue of dam breaching on the lower Snake River, the EIS is expected to “inform future dialog”

Although the report concludes that dam breaching would have long-term benefits to fish in the Snake River because of improved rearing and migration conditions, the number of salmon that would survive and return to spawn is difficult to estimate because of the close correlation between ocean conditions and salmon survival.

What happened to the fish?

Recent research shows that historical returns on Northwest fish runs hovered around six million fish in the 1800’s. However, by the time Bonneville Dam began construction on the Columbia River in the 1930s, fish returns were down to around 500,000.

What caused the decline?

During the 1800’s, several manmade factors began to decimate Northwest fish runs including:

  • Overfishing – Columbia River cannery operations grew from one cannery in 1866 to more than 50 by 1900,
  • Pollution and silting form mining operations,
  • Habitat destruction from logging and
  • Numerous private and public dams which cut access to traditional fish spawning grounds, none of which had fish ladders to help with passage to spawning grounds

It is also acknowledged that construction of federal dams from 1938 to 1975 contributed to the decline of Northwest fish populations. In 1991, the Snake River Sockeye salmon was listed under the Endangered Species Act with more species to follow.

The four H’s of fish survival

Biologists use four broad categories to define human impacts on wild fish and their environment. Specifically, they are harvest, habitat, hydro and hatcheries. While the specific details vary, the bottom line is that wherever there is overharvest, habitat degradation, hydroelectric dams and the widespread use of production hatcheries, wild fish populations will be impacted.

Efforts to improve fish populations throughout their native range must look at all four H’s in order to determine how to best support fish survival.

While human activities caused significant declines in salmon abundance starting in the 1800’s, particularly salmon habitat loss, the last 50 years have seen huge gains in salmon numbers due to supplemental hatchery production, enhanced fish passage, habitat restoration and harvest limits.

A turning point

In 1995, a turning point for fish survival in the Federal Columbia River Power System (FCRPS) occurred when the National Oceanic and Atmospheric Administration (NOAA) issued a Biological Opinion for the 31 federal dams in the Columbia River Basin. In 2000, the first surface passage for juvenile fish was installed which immediately saw significant increases in fish populations.

By 2008, surface passage was completed at all Lower Snake River and Columbia FCRPS dams with 2.4 million fish returning in 2014, the largest return in 100 years. While good news, this is still a long way from 6 million fish of the 1800’s.

The way forward

The preferred alternative of the draft EIS released Feb. 28, 2020, seeks to balance the river system’s goals while testing whether increased spills would improve fish runs. Improving fish habitat is also focus, such as the water-cooling systems developed by district scientists, biologists and engineers at Lower Granite and Little Goose Dams.

While only 7 percent of fish move through the dam turbines that generate electricity, manufacturing and installation of new “fish-friendly” turbines are underway. Each improvement at the dams incrementally increases the survival rate of fish. Taken together, the accumulation of improvements result in a larger overall gain.

Modified spillway weirs, which provide passage for about 37 percent of the fish moving downriver, are from a shallower portion of the watercourse which the fish prefer as it is less turbulent, thus reducing fish disorientation and susceptibility to predation and injury.

As a result, fish survival rates past each of the eight federal dams on the system are between 95 and 97 percent.

Today, the Columbia and Snake Rivers produce most of the wild and hatchery Chinook salmon on the West Coast with the highest survival rate thanks to the dams’ focus on fish passage. While Snake/Columbia River salmon populations are increasing (even with dams), salmon in other critical areas such as the Puget Sound and even the Frazer River in Canada which has no dams, are slowly declining over time according to NOAA. The difference? Dedicated fish passage on dams along the Snake/Columbia River.


The Independent Scientific Advisory Board, a panel of scientists that advises the Northwest Power and Conservation Council, concluded in 2015 that the Columbia and Snake Rivers may now produce more juvenile salmon than occurred prior to dams and human development, if hatchery fish are included.

While ocean conditions impact salmon survival to adulthood, data indicates that improved passage methods through dams have resulted in more juvenile fish getting to the ocean. All this while still providing clean, reliable energy for five million homes, flood risk management for millions of residents across the state, irrigation for agricultural land vital to our state’s economy and 500 miles of fuel-efficient, lowest carbon-emission transportation for hard-working farmers.

The Washington Grain Commission supports the Pacific Northwest’s Congressionally mandated multi-use river systems benefits of the Snake/Columbia river system. Further, the commission endorse practices and technologies that will continue to increase the population and survival rate of fish passing through the system.


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