Priest Rapids Dam Brochure

The brochure is the public face of the Priest Rapids Project, two dams on the Columbia River built and operated by the Grant County Public Utility District (PUD), a publicly owned power authority headquartered in Ephrata, a small farming town in central Washington about 25 miles north of the dam sites. The Federal Power Commission licensed the project in 1955; construction at Priest Rapids began in 1956. Priest Rapids Dam began generating power in 1959 and was fully complete by 1961 — the date stamped on the cover photograph. Wanapum Dam, roughly 14 miles upstream, was still under construction when this brochure was printed; it came online in 1963.

The geology section quietly aligns itself with what had been, until a few decades earlier, a controversial scientific hypothesis. The text describes "enormous floods of glacial melt-water, released by the bursting of ice-dammed lakes" sweeping repeatedly across the Columbia Plateau — J Harlen Bretz's catastrophic-flood theory, which Bretz had been defending against ridicule since he first published it in 1923. The water source — Glacial Lake Missoula in western Montana, impounded behind a lobe of the continental ice sheet — was only confirmed in 1940. By the early 1960s, geologists were largely on board; the brochure treats the floods as settled fact, citing Grand Coulee and Washtucna Coulee as evidence of their erosive power. Bretz himself didn't receive the Penrose Medal (geology's highest honor) until 1979, at age 96.

The interior spread pairs geology text with a stratigraphic column — a vertical diagram of rock layers, oldest at the bottom, each labeled and measured in feet. The bedrock here is Columbia River Basalt, erupted in dozens of individual lava flows between roughly 6 and 17 million years ago. The brochure names each major unit: Priest Rapids Basalt, Roza Porphyritic Flow, Sentinel Gap Complex, Museum Flow, Rocky Coulee Flows, and others, with individual flows ranging from 30 to 200 feet thick. The right-side text explains how the Columbia River held its course as the land rose around it — cutting down through the uplifting anticlines (arch-shaped folds in the rock) faster than the folds could divert the channel.

A passing reference on the back panel to "the diagram on an earlier page" confirms this is one section of a longer publication; the preceding pages, with their flow diagram, are not present in this scan. The single violet ink on cream uncoated stock is spare and economical. No printer is credited; Grant County PUD's Ephrata address appears twice — once on the cover, once on the back panel.