Summer Flush Update

River fish evolved in the presence of high water

By Rob Breeding

Sadly, about the closest I’ve come to putting my butt in the oar seat this summer has been checking the colored dots on the USGS National Water Information website.

I had plans but life intervened.

The good news is that as I peered at Montana’s data in mid-July, there wasn’t a single red dot on the map. Instead there’s just a smattering of orange, lots of green (that’s basically average flows) and then as you move east the dots are mostly blue (90th percentile) with even a couple black dots for rivers running high.

Even though the forks of the Flathead are orange, both rivers were running about 2,300 cubic feet per second. That’s just a little shy of my favorite flow for both the Middle and North forks. The Middle Fork will still give you a thrill at that level, but the pucker factor on Bonecrusher isn’t quite so puckery. And in the mid-2,000s I can still float my hard boat on the North Fork without dragging too much in the skinny parts.

The major rivers out east are just barely moving into fishing shape. Actually, the Clark’s Fork of the Yellowstone looked more like mid-May coffee and cream than it did a fishable trout stream the other day. And the tailwater fishery on the Bighorn River near St. Xavier is running nearly double its average flow for this time of year: 10,000 cfs and rising.

My plan was to have an intimate relationship with the Bighorn this summer, learning to fish it and possibly even resuming my guiding career down the road. Oh well.

Still, the reports from the shops in Fort Smith are that the river is fishing well. Of course, if you’re a fly shop on a river anywhere in Montana in mid-July you can hardly afford to report the fishing is poor, unless your river resembles the Clark’s Fork. And even then you might hedge a bit.

I’m going to head down to the Bighorn this weekend anyway and give it a whirl.

All that water is a good thing, even if it makes the fishing a little more challenging. For rivers, high flows are a kind of colonic, flushing out the nasty rotten stuff and leaving behind a clean river channel. High flows clear sediment from spawning gravel, move woody debris about and keep river temperatures in the trout comfort zone.

It’s tempting to look at all those high flows and assume it’s water Montana could use that’s instead wasted as it flows into one of the less desirable states downstream. But a healthy river needs its annual flush, so long as it’s of limited duration.

River fish evolved in the presence of high water. In the extreme you get strange species like the humpback chub, which lives in the Colorado River at the bottom of the Grand Canyon. I suspect the chub got its namesake bump as an adaptation for living in what was once one of the solar system’s wildest rivers — pre-Glen Canyon Dam at least. When the Colorado was rolling at 100,000-plus cfs and moving bus-sized boulders around the channel, that humpback generated downforce that helped the fish cling to the bottom instead of being washed down to the Sea of Cortez.

Trout can manage in pretty extreme conditions as well. Springtime coffee and cream? That’s nothing for a trout. In fact, with all that stuff moving downstream they can put on weight in high water.

Trout feed efficiently in surprisingly dirty water. A few years back I wrote about a sediment disaster in Wyoming’s Shoshone River, which looked like self-leveling concrete at one point. A few months later fish counts had nearly returned to pre-disaster levels.

Still, I pine for summer flows. It’s time to catch a few fish.

Rob Breeding is the editor of

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