The Lewis River Hydroelectric Projects - PacifiCorp

provide strength, porous gravels channel rainwater safely out of the dam,
and dense clay forms impervious barriers.
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Caption:
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Captions:
Aerial photo showing Yale and Saddle Dams together Saddle Dam is part of a
two-dam system that creates Yale Lake. Just east of here is Yale Dam—the
primary dam, which contains the hydroelectric facilities. Saddle Dam has
no hydroelectric facilities. It acts as an auxiliary to Yale—preventing the
lake from spilling out through this low area (“saddle”) between the hills.
Photo of diversion tunnel While you’re building a dam, where do you put
the river Here at Yale Dam, workers diverted the river entirely around
the dam site, through a 40-foot-diameter tunnel bored through the
bedrock.
Photo of clay embankment along roadside The impermeable layers in the
Lewis River’s embankment dams are made of locally-gathered blue-gray
volcanic clay. Soil scientists supervised the collecting, sifting, and drying
of this clay, to ensure that it was of a consistent high quality.
Hydro-stats: Hydroelectric power icon Yale Dam and Saddle Dam: Year completed—
1953; Crest length—1305 feet (Yale), 1600 feet (Saddle); Maximum
height—323 feet (Yale), 40 feet (Saddle); Annual power generation:
560,398 Mwh (enough to power over 70,000 homes).
Images:
Diagrams and cutaways of concrete arch and embankment dams,
showing differences (we can’t show specifics of Lewis River dams’
construction, but general diagrams should be fine). Photos of Saddle Dam
construction, if available.
Appendix 1: panel profiles Lewis River Draft I&E Plan page 30