Wednesday, August 1, 2018

Saint Croix Falls Hydro Dam

John A Weeks III
The gated spillway used to be a log sluice. But it obviously has a Tainter gate now.

I learned of this dam while studying the Nevers Dam. I had planned on skipping yet another hydro dam until I saw this image. That is the steepest, highest hydro jump I have ever seen.
Ben Hanson Photo, July 2016
After the storm
Evidently Ben had access to the powerhouse and was able to get a shot from the corner of the powerhouse next to the spillway. Looking at the satellite image, there is a gated spillway at the north end of the dam. The overview below shows that spillway can pass a lot of water so the storm that created the above flow over the fixed spillway must have been really impressive. I wonder if some of the boards on top of the spillway were removed in anticipation of the storm or if the gaps are a sign of lax maintenance. The high, sharp hydraulic jump is caused by the water level being so high. The water level is so high because a wide fixed spillway is filling a narrow discharge channel.
Kyle Ahlborn Photo, July 2017
The 59' high dam creates a reservoir that covers the 55' drop in the river.
John A Weeks III, 1.5x and cropped

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