The Pacific Northwest/Pacific Southwest Intertie is the high-voltage electron highway of transmission lines that allows the Columbia River to flow to California in the form of electricity.

The Intertie was Carl Magnusson’s idea, back in 1919, but it took 45 years to come to fruition. The University of Washington engineering professor envisioned a series of high-voltage power lines linking the Pacific Northwest with the Pacific Southwest states. President Franklin Roosevelt adopted the idea as part of his rationale for the Bonneville Power Administration in the 1930s — federally owned transmission lines that would link the major population centers of the West. But it was the drought of 1948 that finally jump-started the idea and made it happen.

In that year, California suffered as the drought reduced hydropower production. Pacific Gas & Electric Company, which had underestimated future demand for electricity and, as a result, underbuilt its generation system, faced the potential for blackouts. The state ordered immediate 20-percent reductions in electricity usage, and leaders of the utility and the state government looked hopefully north to the vast and seemingly untouched water resources of the Northwest. A California congressman even proposed to divert the river to his state.

Rational minds prevailed, however, and over the next five years the proposal for linking the Northwest and Southwest with high-voltage lines gained momentum. Such a transmission system would allow the two regions to share electricity, and thus alleviate shortages, provide power in emergencies, reduce California’s dependence on oil-burning power plants and help serve the power demand of defense industries during the Korean War.

For a time, the West Coast transmission proposal bogged down in Congress, where it landed because of its interstate nature and potentially high cost. Its primary sponsors were federal agencies including the Bureau of Reclamation and the Federal Power Commission; critics included Northwest governors, who worried that the lines would siphon Columbia River power to California that otherwise would help boost economic development in their own states. The Idaho Public Utilities Commission declared in 1951 that the proposal would only serve the interests of those who backed a Socialist power regime in the West, and that was a powerful metaphor in the McCarthy era of public witch-hunting for un-American activities. It didn’t help, either, that President Eisenhower’s administration favored private development of power facilities, or partnerships of public and private agencies, over federal involvement, and discouraged new federal water projects.

The idea languished through most of the 1950s, but gained momentum again late in the decade as the price of oil more than doubled (this increased the cost of electricity produced at oil-fired power plants), the aluminum market slumped and Bonneville faced its first deficits because it could not find a market in the Northwest for much of its surplus power. But there to the south gleamed the golden promise of power-hungry California.

In 1958, Pacific Gas & Electric proposed construction of a high-voltage line between California and Oregon, in conjunction with the California-Oregon Power Company (this utility eventually would merge with Portland-based Pacific Power & Light). The idea found favor in Congress, where committees conducted hearings in the early 1960s. But it was the events of 1964, collectively, that finally carried the transmission system, to be named the Pacific Northwest/Pacific Southwest Intertie, from dream to reality. In that year Congress ratified the Columbia River Treaty, which the United States and Canada had signed in 1961, authorizing the construction of three large storage dams in the Canadian Columbia River Basin for the purpose of maximizing hydropower generation downstream in the United States. Also in 1964 the Pacific Northwest Coordination Agreement was negotiated among parties that included Bonneville, British Columbia and utilities in the Pacific Northwest and the Southwest. This agreement established rules, consistent with the Treaty, for BC Hydro and Bonneville to coordinate the operation of the Columbia River power system to produce the optimum amount of firm (uninterrupted) power and nonfirm (surplus) power. Finally, in 1964 Congress approved the Pacific Northwest Consumer Power Preference Act (Public Law 88-552), which authorized power sales over the Pacific Northwest/Pacific Southwest Intertie, but only power that was surplus to needs in the Northwest. This was politically important, as it insured that investor-owned utilities in the Northwest would have access to federal hydropower that the region’s publicly owned utilities did not need. Public utilities have preference to Bonneville’s power, and investor-owned utilities, which served the majority of customers in Oregon, for example, would not have supported construction of the Intertie unless they had some assurance that they would have access to federal power ahead of public utilities in the Southwest, such as the large municipal utility that serves Los Angeles. With approval of the preference law, Congress appropriated money for initial construction of the federal portion of the Intertie, in Oregon, in the Public Works Appropriation Act of 1965 (Public Law 88-511).

The role of the Canadian Entitlement — Canada’s share of the additional hydropower that would be generated in the Unites States as the result of the Treaty storage — played an important role in approval of the Intertie. Northwest utilities only wanted to sell surplus power on the Intertie, and surplus power is a seasonal commodity in the Northwest, mostly available during the spring and early summer when the mountain snowmelt and the Columbia River dams often generate more power than the region needs. But utilities in California and the Southwest wanted firm power — power that is delivered year-round — and British Columbia wanted to sell it to them from their Treaty entitlement.

“California would consent to the Intertie only if they could get firm power. We didn’t need the Canadian power in the Northwest,” former Bonneville Administrator Charles Luce told author Gene Tollefson, whose history of Bonneville is called BPA and the Struggle for Power at Cost. “There was no political opposition to selling Canadian firm power in California. So all of a sudden, what seemed to us to be a problem and a liability, namely how to market this Canadian power, became an asset and an opportunity.”

On September 17, 1964, President Lyndon Johnson addressed the Intertie Victory Breakfast in Portland, a celebration that took place a day after Johnson met Canadian Prime Minister Lester Pearson at Blaine on the Washington/British Columbia border to proclaim the treaty and, importantly, present a check to Canada for $254 million. That was the calculated value of the Canadian entitlement, the money British Columbia would use from its share of the first 30 years of increased power sales to build its three Treaty dams. In his Portland remarks, Johnson said, “This system is proof of the power of cooperation and unity. You have proved that if we turn away from division, if we just ignore dissention and distrust, there is no limit to our achievements.”

The Intertie consists of both AC and DC lines. Both have been expanded over the years from their initial construction. Today, the AC lines carry up to 4,800 megawatts of electricity, and the DC lines carry up to 3,100. The AC line runs from John Day Dam to Lugo, California, near Los Angeles. The DC lines run from the Celilo substation, near The Dalles Dam, to Sylmar, California, also near Los Angeles.