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Get Outside Georgia

Opinion: Trout fishing on the Chattahoochee River

  • Updated
Buford Dam fishing

Things have been busy hereabouts lately, and as a result, I have been suffering greatly in the fishing department. There just hasn’t been time to get out on the water. That is bad for my disposition and possibly impacts my hairline too, a heavy-duty one-two punch. Clearly, something had to be done.

While I was thinking about what to do, my buddy Scott called me up and said, “Let’s go fishing!” That was all the arm-twisting I needed, for I’m one of those strange people who likes to fish for trout during the colder months of the year.

A few hours later we were on our way to the storied trout waters of the Chattahoochee River.

To be more precise, we were on our way to fish the river below Buford Dam.

Our destination was the “upper tailwater.” “Tailwater” means that it’s a portion of the river located below a dam, while the “upper” designator means that said dam is close by.

Yeah, really close. In fact, from where we were going to fish, the dam itself was an imposing presence located just a little ways upstream.

Fishing the tailwater below Buford Dam is not for the careless or the lackadaisical. The problem is that if the dam releases water, the river comes up in a hurry. It’ll rise several feet in just minutes as zillions of gallons of icy water start making their way to the Gulf of Mexico. It’ll get you if you don’t watch out, and being gotten by a water release is a bad thing.

Yes, you’ve got to be careful on any tailwater.

But we had done our homework, and we felt confident that on that day we wouldn’t be washed away.

Once we arrived, we put on all the wading gear (including the mandatory life preservers, required by law on this part of the river), rigged up the rods, and made our way to the water.

But then…

“What’s that smell?” Scott asked.

The aroma my friend referred to was sharp, biting, and faintly metallic.

It was the aroma of “turnover.”

You too may have noticed the astringent aromatics below the dam these last few weeks. What’s the cause? Well, I’m glad you asked – but get ready for a little bit of chemistry.

The smell below the dam right now, as well as the slightly off-putting pea-green hue to the water, stem from something called “turnover.” It happens once a year in the lake above the dam.

To understand turnover, you must turn the calendar back to the warm months of last summer when the lake stratifies (that is, it forms layers) based on water temperature. At the surface, there’s the epilimnion, a highly oxygenated zone 15 to 30 feet thick. Below that is the “metalimnion” (most just call it the thermocline), a 20- to 30-foot-thick zone where temperature drops quickly – as much as 2 degrees per foot of depth.

And below that? Below about 60 feet there’s the hypolimnion, a zone of very cold water with very little dissolved oxygen.

Now here comes the chemistry. Where there’s little oxygen in the water, as is the case in lowest layer (the hypolimnion), metals and sulfides (found in bottom sediments) tend to dissolve. But if more oxygen is present, those same dissolved metals tend to form compounds that precipitate out and eventually settle to the bottom.

In a nutshell, then, that’s the summertime situation. You’ve got a layer of highly oxygenated water floating on top of a zone of cold, oxygen-poor water – and deep down below it, a cold, oxygen-poor zone holds a lot of dissolved metals and sulfides.

But then warm months give way to colder ones. The surface layers cool, and the cooler water (being more dense) starts to sink and the water layers “turn over.” Technically speaking, that’s the “turnover” that you hear so much about. Historically, it seems to happen in the weeks around Christmas.

Turnover is important precisely because it (aided by the stirring effects of seasonal winds) causes the layers to mix. The eventual result is a single mass of unstratified water with dissolved oxygen present throughout the entire water mass. In the presence of that oxygen, those previously dissolved metals now form compounds that begin to precipitate out. The precipitates cloud the water for a while, giving the river that vaguely pea-green color (and that faint but distinct metallic odor) that you encounter below the dam right now.

But not to worry. The green haze (and the odor too) won’t last forever. Remember that the color comes from precipitates, and those precipitates are settling out even as we speak. Once they settle out, the lake’s water will clear up on its own.

Meanwhile, in the river itself, the precipitates that have passed through the dam soon settle out too. The result is that even in the midst of turnover, the water clears noticeably as you move downstream. Pretty soon, the upper part of the tailwater will be back to its more familiar clear-and-odorless state. The fishing will improve, and the river will once again be a more pleasant place to be.

Turnover? No worries. It’s just a temporary thing.

And that’s good news for crazy people like me who like to fish in freezing cold rivers in the middle of winter!