Tag Archives: New York Canal

Arrowrock Dam Spillway


Arrowrock Dam on the Boise River was complete in 1915. For nine years it was the tallest  dam in the world. It was built to hold back water to feed the newly completed New York Canal, the largest of the irrigation projects in the Boise Valley.

As a kid I was fascinated by the massive spillway that passes to the north of the dam. Unfortunately it seems running the spillway is tough on the bull trout that call Arrowrock Reservoir home and use of the spillway was curtailed some time ago.

Until this year. We have a record snowpack and it seems running the spillway has become an option!

I checked it out on Thursday, May 18, 2017 and sure enough the spillway was running! Here’s a little three-minute movie about it.


The day after I posted this video of the spillway running I checked the spillway out again. It has warmed up and the snowpack in the upper elevations is melting. The spillway is no longer running. It is gushing —