Scientists Make Dam Suggestionsby Michael Jamison
The Missoulian, May 26, 2007
KALISPELL - When most folks think of climate change, if they think of it at all, they think of atmospheric warming.
But the fact is, air is fickle. It gains and loses heat rapidly, making it wildly unpredictable.
But water is stable. Water holds heat very well, which, in a warming world, could prove disastrous for sensitive fisheries.
For years, the waters of the Columbia River Basin have provided a focal point for scientists, because the fishery there is badly disrupted by, among other things, a string of federal hydroelectric dams. Much money and energy has been spent mitigating the effects of those dams on fish and wildlife, and trying to assure a secure future for salmon and other sensitive species there.
With so much investment already in place, then, it makes sense that scientists would want to know how climate change might affect all their work, and how the river system might respond to a warming world.
Last week, a panel of independent scientists - including several from within private industry - delivered a report to the Northwest Power and Conservation Council, advising how best to manage the Columbia's dams in response to current climate change.
"Warming of the global climate is unequivocal," the report declares, citing increases to both air and ocean temperatures, as well as melting ice and snowpack and a rise in mean sea level.
Of the past 12 years, the report states, 11 rank as the warmest since records began in the mid-1800s. And the linear warming trend for the past 50 years is nearly twice that of the past 100 years.
According to the report, the Pacific Northwest region has warmed a full 50 percent more than the global average over the same period, and is expected to continue to climb.
And the regional forecast is not just for warmer, but also for wetter (during the winter) and drier (during the summer).
All of which will change water quality and quantity throughout the Columbia River system.
So what about all those sensitive species, many of which already teeter on survival's edge?
The report suggests that "dams on the Columbia and Snake rivers could be operated in ways that reduce the potential impacts of climate change on salmon and steelhead."
The Independent Scientific Advisory Board report, released May 16, recommends several possible changes to the way hydroelectric dams are operated throughout the year.
More cold water could be released from behind the dams during the dog days, for instance, to cool river temperatures when salmon and steelhead are migrating. And more cold-water spawning areas in the headwaters of rivers could be protected and restored.
Likewise, more effort could be put into reducing populations of fish that eat young salmon, knocking down the numbers of pike minnow, walleye and bass.
But each recommendation, of course, comes with tradeoffs. The dams must be controlled, not only with downstream fisheries in mind, but also for flood control and hydroelectric production.
And headwater protections come with a price tag. Sport anglers might balk at efforts to reduce popular game species.
"For the council, this report reminds us how important it is to consider all potential climate-related impacts as we devise strategies to mitigate the impacts of hydropower on fish and wildlife and prioritize actions in the future," said Tom Karier, chairman of the NPCC.
Karier's council is an agency of the states of Montana, Idaho, Oregon and Washington, directed by Congress to balance the needs of fish and wildlife with the need for affordable and reliable hydropower.
If that balance is not found relative to climate warming, the report warns of considerable changes to the habitat ranges of critical species. The ISAB report predicts many species of insects (fish food), birds (fish predators) and trees (fish shade and habitat) will move to higher elevations and northerly latitudes as the world warms.
The future also hints at more wildfires, more bug infestations, more flooding, more drought, more forest disease.
Too much, or too little, water in the rivers will impact egg survival, and increasing temperatures can cause a premature hatch.
The report anticipates that in the next 25 years, temperature increases will render between 2 percent and 7 percent of current trout habitat unsuitable; 5 percent to 20 percent by 2060; 8 percent to 33 percent by 2090.
Salmon and steelhead habitat may be more severely affected, because those fish migrate through, or spawn in, lower and therefore warmer areas of the region.
According to the report, "Salmon habitat loss would be most severe in Oregon and Idaho, with potential losses exceeding 40 percent by 2090."
Bull trout, a species particularly fond of cold water, could lose 22 percent to 92 percent of its habitat range.
Possible solutions, in addition to augmenting cool-water flows, include installing removable weirs to reduce the time young salmon and steelhead spend in the warm water of dam forebays. (Those weirs already have been installed at Lower Granite and Ice Harbor dams on the Snake River, and are being considered for more dams.)
And when water temperatures are extremely high, the report recommends that migrating fish could be barged upstream and into cooler waters.
Ultimately, however, the authors admit the range of solutions available locally is limited, and "only global strategies for reducing greenhouse gas emissions will completely address climate change impacts in the Columbia River Basin," the report concludes.
To view the full report, go to www.nwcouncil.org/library/isab/isab2007-2.htm
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