(
HAER, none of the photos are digitized;
Satellite)
Andy Michel
posted seven photos with the comment: "Arrowrock Dam - Built in 1915!!!"
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" At the time of its dedication in 1915, the Arrowrock Dam was the highest dam in the world at 350 feet [76m], a title it would hold until 1925 when it was surpassed by the Schraeh Dam in Switzerland. Civil engineers tested the technological limits of the time to construct this engineering marvel" [
asce]
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nps
The dam was built to provide water for irrigation. "Today, Idaho produces 30 percent of the nation’s potatoes, 53 percent of its Austrian winter peas, and a fifth of its barley, mint, sugar beets, and wrinkled seed peas." "Before construction on the dam could begin, the river was diverted around the site through a 470-foot-long tunnel. In late February 1912, excavation for the dam foundation began. When workers discovered a lava bench between 20 and 50 feet thick, it had to be removed because lava was not considered a suitable foundation material....In November 1912, as the first concrete was poured, engineers were just learning that a massive pour of concrete, as it hardens, creates great internal heat and expansion. Engineers worried that subsequent cooling and contraction would create dangerous cracks in the interior of the dam. For this reason, engineers decided to use a mixture of Portland cement and sand in the construction of Arrowrock. The strength of the mixture proved, Simonds writes, “to be only slightly less than that of pure cement after 6 months, and comparable in strength after 1 year.” The sand-cement, however, proved to be highly absorbent, and the consequent freezing and thawing caused deterioration. Between 1935 and 1937, Arrowrock’s downstream face was repaired with a new slab of concrete, and the dam was raised five feet." |
I noticed that the only other available street view looks different. I've learned that the level of the tailwater varies dramatically.
Of the three photos that the
USBR has, the first two have a high tailwater and the third is lower. The 15mw powerhouse was added in Mar 2010.
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IntermountainHistories, 2 of 4
"The Arrowrock Dam is considered the grandfather of many famous dams for example, the Hoover and Shasta Dam. The Hoover and Shasta Dam’s built with the same system engineer Frank Crowe developed the Crowe Cable System....The dam revolutionized the way dams were constructed with similar techniques as well as similar design and models." |
The high outlet conduits appear to be used much more in the past. I wonder if the powerhouse makes them obsolete.
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Fritz Kennedy posted
All calm up at Arrowrock.
[Some comments accuse this of being AI or photo manipulation because the sun's position and the shadows don't agree.] |
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Merilie Dawn Blickenstaff commented on Fritz's post
You took a beautiful photo of Arrowrock dam! I took this after Snowmageddon of 2017 when the water was coming over the spillway. |
The spillway is a tumble bay on the right descending abutment.
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Mary Jean Delia Lovingfoss commented on Fritz's post
Was this pic from last year? Here is current [Sep 3, 2026] water level.
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Karen Gray commented on Fritz's post
Taken 8/3/26
[It looks like the reservoir is almost as low as the tailwater is high. I'm really confused. Why would the reservoir be so low and the tailwater so high? A low reservoir implies dry conditions while a high tailway implies wet conditions.] |
About 1.5 months later, the tailwater is low again.
I cranked up Google Earth to verify that there is incredible variability in the tailwater level.
It was high in Aug 2011, but...
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| Google Earth, Aug 2012 |
...low in the next older image.
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| Google Earth, Oct 2010 |
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Andy Michel posted
Arrowrock Dam Comparison with the Flatiron Building in New York The Caldwell Tribune October 1st, 1915 |
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| Underestimated Arsenal posted [The post has a long description.] |
Sep 5, 2026:
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Mindy Mcgrew posted
Arrowrock dam yesterday. I'd love to hear the story on this!
[I looked at about 20 comments and their replies and the consensus is that he parked it there to get a good spot for Labor Day, but then there were some heavy rains while he was gone. |
At the beginning of this reel we see that the cables are attached to the RV.
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Jereb Allen commented on Mindy's post
Facebook Reel
B&W Wrecker sent a heavy and their dive team to pull him out. Guy started it up and drove away. |
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