By Tom Gentle Dams pose stark and difficult choices in the debate about the future of salmon. There is little good that can be said about the effects dams have on salmon populations. On the other hand, few would deny that dams have made our lives better. It's important to note that any discussion of dams involves two distinct sets of dams. 1) The federal dams in the Columbia-Snake River system, which includes 14 dams on the Columbia and 13 on the Snake. These dams constitute a sophisticated, interlinked system that generates electricity and provides benefits to navigation, flood control and irrigation to the entire region and beyond. 2) The dams that are not part of the Federal Columbia River Power System. Within the Columbia Basin--including, in Oregon, the Willamette and Deschutes rivers--there are 136 dams that provide hydropower and other benefits. In addition, there are as many as 3,600 smaller dams in Oregon that provide water for municipal, industrial, irrigation, livestock and rural uses. |
 Dams restrict fish passage to the ocean and back to spawning grounds. |
There are two major issues with dams.
- Dams block fish passage upstream to areas where salmon once reproduced
and spent their early lives. Grand Coulee on the Columbia River and Hells
Canyon on the Snake permanently block 1,200 miles of those mainstem rivers
once used by salmon. Similarly, dams block rivers and streams in the Willamette
Valley, central Oregon, Klamath County and southeastern Oregon.
- Dams reduce the number of juvenile salmon that migrate downstream to the ocean. On the Columbia-Snake system, juvenile salmon that remain in the river on their downstream migration must pass eight dams. An estimated 10 to 15 percent die passing through the turbines at each dam--which means 60 to 70 percent of those fish will never reach the ocean. The dams also create a series of lakes, slowing the current and delaying downstream migration. The delay interferes with internal biological changes that enable the young salmon to survive in saltwater. In addition, the slack water exposes them to northern pikeminnows, also known as squawfish, and other predators, including several introduced species, walleye and bass.
A number of solutions have been proposed to reduce the harm caused by dams:
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 Matt Adams, a technician with the Oregon Department of Fish and Wildlife, holds a chinook salmon just downstream from Bonneville Dam on the Columbia River. Adams works at his agency's nearby Bonneville fish hatchery. |
Each of these solutions is surrounded by controversy and scientific uncertainty. For example, spilling water over the dams is costly in terms of lost electric power generation. The National Research Council endorsed barging as an effective approach for moving juvenile salmon downstream, though noted that more information is needed about how many of the young salmon return as adults and successfully spawn.
"Some of these solutions, like barging, attempt to get around natural processes rather than create conditions that salmon are adapted to. Instead, we should be looking for solutions that take into account the biological and physical conditions that salmon need to survive," said Bill Liss, an OSU fisheries biologist.
As an example, he pointed to the massive release of water on the Colorado River that created new gravel bars, pools and other conditions needed by native fish. He also noted that new surface bypass systems to get smolts past the turbines take into account the surface-oriented nature of migrating juvenile salmon. "This approach has promise, and it doesn't mean we have to return the river to its pre-European condition."
Removal or breaching of dams is being seriously considered for some non-Columbia-Snake system dams. "Many of these dams are licensed by the Federal Energy Regulatory Commission. When their licenses expire, they may have to install fish passage facilities to get renewed if required by the appropriate federal agency to protect salmon. It's too costly for some of the dam operators and it's possible the dams will be removed," said Peter Paquet of the Northwest Power Planning Council.
Jackson Street Dam in Medford is being replaced by a smaller structure that will allow fish passage, and Savage Rapids Dam on the Rogue near Grants Pass is under consideration for removal.
Breaching dams in the Columbia-Snake system is also being considered, an action that would have more far-reaching consequences as well as opposition. The U.S. Army Corps of Engineers is conducting a feasibility study to remove the earthen portion of four lower Snake River dams. It is felt that breaching would reduce the number of salmon that die passing each dam, increase the flow of water and speed migrating salmon downriver, and create spawning habitat. The Corps of Engineers is also studying a proposal to lower the 76-mile-long reservoir behind John Day Dam to expose what scientists say is about 40 miles of ideal fall chinook spawning ground.
These studies are to be completed in 1999. Among the issues raised by critics of these proposals are:
- Loss of electrical power generating capacity of five dams and the revenues
from selling the electricity. An increase in reliance on natural gas, a
fossil fuel, for electricity.
- Loss of the shipping corridor from Lewiston, Idaho, to Portland. An
estimated $440 million worth of commodities move on the lower Snake River
every year.
- Loss of irrigation for 36,000 irrigated acres that are used to grow grapes, apples and potatoes.
The debate will begin in earnest when the Corps of Engineers' report and recommendations are made public. At the center of the debate will be an issue raised by Bruce Lovelin, executive director of the Columbia River Alliance for Fish, Commerce, and Communities.
"We know the economic consequences of the proposed permanent drawdowns are great. However, the biological merits of dam removal have not been made clear," he said.