The Innocuous River Hazard That Kills 40 People a Year

Deadly hydraulic hazards can form behind low head dams and small pour-overs

By Jerry Castellini

Illustrations by Koren Shadmi

March 8, 2020

I went rafting with my family on Idaho's Salmon River, "The River of No Return." Owing to a quirk of river hydrology, it almost lived up to its name.

Deadly hydraulic hazards can form behind low head dams and small pour-overs

We ran several big rapids, and then an innocuous one threw me from the raft. I surfaced quickly. My family, on the far side of a minor pour-over, set the raft up for a rescue.

Deadly hydraulic hazards can form behind low head dams and small pour-overs

Suddenly, I was pulled underwater and tumbled around and around as if in a washing machine. I fought to get to the surface but was held under for what seemed like hours.

Deadly hydraulic hazards can form behind low head dams and small pour-overs

I was running out of air. Instead of fighting to go up, I swam down, where I was able to catch the river current. It kicked me out of the hole downstream.

Deadly hydraulic hazards can form behind low head dams and small pour-overs

I was rescued quickly and treated for shock and hypothermia. I was otherwise OK, but the experience still haunts me.

This article appeared in the March/April 2020 edition with the headline "River of No Return."

ASK THE EXPERT

Matthew Lindon is a hydrologist who works with the Association of State Dam Safety Officials.

"Forty or more people a year die in 'submerged hydraulic jumps' like the one that caught Jerry. They form behind low head dams, diversion structures, and small, low rapids. Go around them if possible, but if you get trapped, swim down and out."