WITH twice the water of the Nile and 10 times the flow of the Colorado, the mighty Columbia River and its tributaries represent nature at its most powerful. Churning through 30 federal hydroelectric dams, the Columbia system holds 40 percent of all United States hydropower potential and supplies 62 percent of the Pacific Northwest's electricity.
For years, this has kept utility bills here the lowest in the nation and still meant power to spare for air-conditioners 900 miles to the south in Los Angeles.
But with economic and population growth - the equivalent of adding another Portland, Ore., every year during the 1980s - and increased environmental awareness as well, times are changing.
``The surplus is gone,'' says Jim Goller of Idaho, chairman of the four-state Northwest Power Planning Council, which was established in 1980 by Congress to oversee regional power and the two principal federal agencies, the US Army Corps of Engineers and the Bonneville Power Administration.
The council's new energy plan emphasizes conservation - 1,500 megawatts during the next decade, with a total available savings of 4,600 megawatts over a period of 20 years. (It takes about 1,000 megawatts to power Seattle for a year.) This amounts to the largest coordinated US conservation effort ever.
It won't be cheap, says Mr. Goller. Conserving that much energy will cost 2 1/2 cents per kilowatt-hour in changes to commercial and residential structures, adjustments in industrial and agricultural practices, and new efficiencies in power generation and transmission. That could total $7 billion, but is still only about half what new thermal power-generating capacity would cost.
Bonneville Power gets the rest of its generating capacity from coal-fired and nuclear plants. Power Council plans include streamlining the process for new plant design and approval, and ``pinning down the cost and availability'' of such ``promising'' energy sources as wind, solar, geothermal, and biomass. Lurking in the background are the two partly completed nuclear facilities that were mothballed when the Washington Public Power Supply System defaulted on its bonds.
BUT the emphasis over the near term is clearly on saving rather than generating, and the key to making it work will be convincing the 170 electric utilities in Oregon, Washington, Idaho, and Montana that conservation pays.
The Power Planning Council - which makes recommendations but can't order anybody to do anything - is urging changes to state regulations so that utility profits would be linked to how much energy is saved as well as how much power is sold.
``It's been a selling job showing utilities they can treat conservation as a resource just as they can new generating capability,'' Goller says.
Long before President Franklin D. Roosevelt dedicated the first hydropower dam in the Northwest, the mighty Columbia was home to hundreds of stocks of wild salmon. If several salmon stocks are listed under the Endangered Species Act, as is expected, then the Bonneville Power Administration, the US Army Corps of Engineers, utilities throughout the region - and ultimately everyone who lives here - may have no choice but to conserve.