Dynamite blast begins construction of Howard A. Hanson Dam on February 3, 1959.

  • By Alan J. Stein
  • Posted 9/10/2001
  • HistoryLink.org Essay 3550
On February 3, 1959, a dynamite blast marks the beginning of construction of Howard A. Hanson Dam. The dam, located 35 miles southeast of Seattle in Eagle Gorge on the Green River, will take three years to build. It is named for Howard A. Hanson (d. 1957), Seattle attorney and long-time promoter of flood control in the Green River Valley.

Years in the Making

Soon after farming became widespread in South King County in the 1880s, flood control was always an issue. Between 1900 and 1960, more than 30 major floods occurred, resulting in millions of dollars of damages. Early farmers used to dynamite logjams in the river, attempting to divert the floods into other farmers’ lands, while others built farm property on risers or mounds and hoped for the best.

In 1926, the Associated Improvement Clubs of South King County was formed, and one of their first projects was flood control. By the 1930s, they realized that the problem was more than they could handle, and the Army Corps of Engineers was brought in. Years of studies, momentarily delayed by World War II, led to the creation of a reservoir dam far upstream that would hold back the destructive floods that normally occurred in November and December.

An early proponent of the dam was Howard A. Hanson, Seattle attorney and early twentieth century State Legislator. Hanson promoted the regional benefits of the dam, raising $2 million from the State and King County. Hanson died in 1957, and a year later the dam, originally called Eagle Gorge Dam, was renamed Howard A. Hanson Dam by an Act of Congress.

A Wet Dam Blast

On February 3, 1959, hundreds of visitors traveled to the dam site to witness groundbreaking ceremonies. Work had already begun relocating 13.7 of Northern Pacific Railway line three years earlier, but this date would mark actual construction of the dam. Work on the dam would take three years to complete.

At 11:40 a.m., Dean Eastman, president of the Seattle Chamber of Commerce pressed the button setting off the inaugural blast. A sheet of flame, filled with rock and debris shot skyward from a rock ridge between the spectators and the Green River. The attendees were completely safe, their only discomfort coming from rain, cold wind, and ankle deep mud.

A ceremonial shovelful of dirt was unearthed, and with that the construction began. A diversion tunnel was built first to channel the Green River away from the construction site, and then the dam began rising. The only setback during construction was a flood in November 1959 that wiped out a cofferdam. Nevertheless, work was completed a few months ahead of schedule and the dam was dedicated on May 12, 1962.


Sources: Clarence B. Bagley, History of King County Vol. 1 (Chicago: S.J. Clarke Publishing Co, 1929), 712-727; “Gorge Dam Begun,” The Seattle Times, February 3, 1959, p. 16; “Eagle Gorge Dam Started,” Seattle Post-Intelligencer , February 4, 1959, p. 1; “Howard A. Hanson Dam, End to Flood Threats; Provides Other Benefits to Valley,” Kent News-Journal, May 9, 1962, pp. B6-7; U.S. Army Corps of Engineers, Howard A. Hanson Dam, Eagle Gorge, Green River, King County, Washington (Seattle, 1963).

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