How Arrowrock Dam Built A Town And Irrigated A Valley 100 Years Ago

May 12, 2015

Arrowrock Dam is celebrating its 100th birthday this year. “It was a monumental effort,” says Kelsey Doncaster. He’s been studying the dam as a historian with the Bureau of Reclamation Columbia Cascades area office in Yakima, Washington.

He says it’s a marvel of engineering that keeps irrigation canals in the Treasure Valley full, while controlling flooding of the Boise River.

“It’s a thirsty valley like anywhere; we live in the arid West. Water is a precious commodity and the dam was able to provide a large amount of stored water for the valley and also provide flood control.”

Doncaster say in 1900, the valley was stuck between two extremes. Depending on the time of year there was either too much water – which led to flooding – or not enough water for irrigation.

So engineers decided to build a dam. They chose an isolated area, 22 miles east of Boise.

“We don’t think of that today. Today it’s just a car drive away; it’s not a big deal. But how back then it was very, very remote and it was hard to get to and how they had to be completely self-sufficient to make a go of it.”

A town of 1,400 people grew up around the building of the dam.
Credit WaterArchives.org / Flickr

Doncaster says a special railroad was constructed to bring materials in and out of the area. And a small town was built up around the dam site to house the builders, engineers and support staff.

“They had dormitories, they had a bunkhouse, they had an icehouse, meat house, grocery store, even had a soda fountain. It really was a full functioning city and that was why they did well with the labor force they had,” Doncaster says.

At its peak, more than 1059 people were working on the dam, but with support personnel, the town housed 1400.

“That doesn’t sound like a lot today but back then, that was a lot of people,” Doncaster says. “They had to provide food, housing, there was a hospital to provide for people that were injured.”

Arrowrock Dam under construction. This photo is one of 400 glass plate negative photographs taken by the Bureau of Reclamation.
Credit WaterArchives.org / Flickr

After four years, the dam was dedicated on October 4, 1915.

This photo shows the dam just before it was dedicated in 1915. The small town can still be seen below the dam.
Credit WaterArchives.org / Flickr

Doncaster says the dam was critical to providing water to the Treasure Valley.

“That water is desperately needed and is something that is very important to the valley and to our history. This is a neat little gem that people in Boise may not know about.”

Doncaster found 400 glass plate negative photographs, mostly by Walter J. Lubkin, a Reclamation photographer at the National Archives in Maryland.

“Many of which we’ve never seen before that show the daily life in the camp, the construction techniques and material, how the valley had changed from what it was before to today and so on.”

He’s featuring those photos in a talk about the history of the dam Wednesday at 7 p.m. at the Boise Public Library.

Find Samantha Wright on Twitter @samwrightradio

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