Energy | Ecotrope

Inside Bonneville Dam: 5 Surprising Facts

Ecotrope | July 16, 2012 3:33 a.m. | Updated: Feb. 19, 2013 1:30 p.m.

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Inside Bonneville Dam you can see how high the water level is upstream before taking a 60-foot escalator down into the belly, where you can feel the water rushing through turbines underfoot.

Inside Bonneville Dam you can see how high the water level is upstream before taking a 60-foot escalator down into the belly, where you can feel the water rushing through turbines underfoot.

I got to go on a VIP tour of Bonneville Dam on Saturday as part of an energy policy class I took last semester at Portland State University.

Corps Park Ranger Ryan Braaten took us inside Powerhouse 1 on the Oregon side of the dam, where the generators are a patriotic red, white and blue, and 97 percent of the juvenile fish that go through the turbines survive.

Corps Park Ranger Ryan Braaten took us inside Powerhouse 1 on the Oregon side of the dam, where the generators are a patriotic red, white and blue, and 97 percent of the juvenile fish that go through the turbines survive.

Ryan Braaten, a park ranger with the U.S. Army Corps of Engineers (yeah, the Corps has park rangers), taught us how the dam’s 21 generators make enough electricity to power 900,000 homes. It took 3,000 people four years working 24/7 to build the dam in the mid 1930s. Twenty-six of them died in the process.

The best part was going into the dam itself, where you can feel the force of the Columbia River roaring through the turbines below. I could see how how far below the upstream water level I was and how far the water drops before it re-enters the river.

Obviously, there is a lot to know about Bonneville Dam: The way it reshaped the river, how it affects fish and wildlife, how its hydropower gets to your house …

But there were a few facts that I learned walking through with a VIP tour guide that were genuinely surprising.

1. Fish Need Lights To Get Through It:

Bare bulbs guide migrating fish up through Bonneville Dam's fish ladders. Without these lights, the fish wouldn't swim through the cavernous tunnel.

Bare bulbs guide migrating fish up through Bonneville Dam's fish ladders. Without these lights, the fish wouldn't swim through the cavernous tunnel.

There are fish ladders on both the Washington and Oregon sides of the dam, and on the Washington side, the ladders snake through the power house in a dark concrete tunnel.

“Fish won’t go into the darkness,” said Braaten. “We put lights in the fish ladders so fish think there’s a sun above them.”

You can look into the tunnel and see the lights that guide fish through the passage system. It’s a little eerie, actually.

One other thing I’ve always been curious about: Most of the fish in the fish ladders are swimming through underwater holes. That explains why you don’t see them jumping up the ladder “rungs”, so to speak.

2. Spilled Water Makes Power, Too:

Even when the Corps is spilling water – consciously not putting it through the giant turbines in the powerhouse – the agency is still making some power with two smaller generators. The Corps uses two smaller generators to produce its own power for operations, Braaten said. ** CORRECTION: I thought Braaten said these generators were in the spillway, but they’re actually in a section of the powerhouse that I didn’t even know existed. Here’s how he explained this in an e-mail today:

“We spill water on the side of the powerhouse to attract fish into the ladder and we decided to place 2 generators in that water (fish unit 1 and 2) to capture that energy that would otherwise just pass through the powerhouse.”

3. Juvenile Fish Are Encouraged To Swim Through New Turbines:

Tour guide Ryan Braaten explains how the Corps no longer needs to use these fish screens to divert fish from going through the turbines inside Powerhouse 1. The upgraded turbines are safer for fish than the old bypass system, he said.

Tour guide Ryan Braaten explains how the Corps no longer needs to use these fish screens to divert fish from going through the turbines inside Powerhouse 1. The upgraded turbines are safer for fish than the old bypass system, he said.

Bonneville Dam was equipped with bypass systems to prevent juvenile fish moving downstream from getting ground up and killed by the turbines.

But according to Braaten, the turbines inside Powerhouse 1 on the Oregon side of the dam are now so fish-friendly that the Corps has stopped diverting fish into a bypass system. On the Washington side of the dam, young salmon and steelhead that are migrating downstream are funneled around the dam and released two miles downstream, where the current is faster and there is less chance of them getting eaten by predators.

The Corps discovered 97 percent of the fish that go through the upgraded turbines survive the fall while the bypass system only guaranteed 95 percent survival.

“The new turbines are more fish friendly than the fish bypass,” Braaten said. “It’s safer to get them through quickly than to divert them a couple miles through the bypass.”

So, the Corps gave up the fish bypass on the Oregon side of the river (note, that’s the *downstream* bypass; not the fish ladders going up and around the dam).

4. Fish Are Counted By A Person Who Is Also Reading A Novel:

During slower times for fish passage through Bonneville Dam, it's perfectly acceptable for fish counters to read a book while counting fish.

During slower times for fish passage through Bonneville Dam, it's perfectly acceptable for fish counters to read a book while counting fish.

I should have known that the fish counters at Bonneville Dam are actual people. But I didn’t.

It’s too hard for a computerized counter to accurately count and identify the fish moving upstream through the dam, Braaten said. Some fish take their time, circling backward  on their way through the dam. A computer would count them twice while a person can be more discerning.

Plus, the fish counter needs to discern between adult salmon and so-called “jack” salmon that come back to spawn a year early. Two strings dangling 22-inches apart allow the fish counter to tally the smaller jack salmon and the larger adults. The counter also needs to distinguish wild chinook, which have an adipose fin, from their hatchery counterparts that have been fin-clipped. That’s a tall order for a computerized system.

If you go into the visitor’s center you can peer into the fish counter’s booth. When my tour group did this, however, we found the fish counter on duty was reading a book while tallying the fish passing through the fish window.

“I’m not so sure how comfortable I am with these numbers anymore,” said my classmate Dave Bluestein. “If they’re based on a lady who’s sitting there reading a book.”

But when asked whether this is really the way the fish are supposed to be counted, Braaten was unfazed.

“It’s probably  just a slow time,” he said Braaten. “The fish come through in waves because they travel in schools. So, she keeps her mind going by reading a book.”

At the peak of the runs, 10,000 to 20,000 fish will pass by the counter in an hour.

5. You, Too, Can Go Into The Powerhouse On The Washington Side:

Anyone can enter the belly of Bonneville Dam and see the Skittle-colored generators on the Washington side.

Anyone can enter the belly of Bonneville Dam and see the Skittle-colored generators on the Washington side.

As I noted earlier, our class got the VIP tour of the dam, which included a peek inside Powerhouse 1 on the Oregon side of the dam. The public isn’t normally allowed to enter that powerhouse. But there’s a whole different deal on the Washington side of the dam.

My classmate Kathleen Newman was floored by this.

“I come to Bonneville all the time,” she said. “I always bring my out of town guests to see the dam, and I never knew you could see all this on the Washington side.”

Inside the Washington powerhouse, you’ll descend a 60-foot escalator that was once the longest of its kind west of the Mississippi. Here, in the belly of the dam, you can stand on the yellow and orange generators. The floor is warm from the spinning rotor under your feet, and it’s vibrating from the rush of water through the turbine far below. And on your way out, you can walk across the puddles of water where dam is leaking. (It’s no big deal, according to Braaten. Just put down some floor mats.)

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