Finally got back on the river for a few hours on Friday after a week of clear weather and high afternoon temps. Our annual July so called “Heat Wave” is probably over for the summer. Significantly cooler, wet weather moved in and will be here for at least a week. River flows will increase some (they already have in some watersheds) and fishing will return to normal. I was on one of my favorite sections of the lower Big Hole well before dawn. It was overcast, a bit drizzly and 56 degrees. By 10 AM when I left, air temps had only reached 62 degrees. The waters had cooled significantly and most of my readings were in the low 60s. It was an influential trip from my perspective. The closest river gage had been slightly below 300 CFS for several days. This was the first time I’d ever fished this reach when flows were below 500 CFS. Previously this year, I’d covered this water at between 1000 and 750 CFS several times.
I noticed several things immediately. Riffles became longer stream wise but narrower overall. Some riffle buckets and corners had essentially disappeared while others had moved downstream slightly. Pools and deep runs appeared unchanged as the overall depth was probably just a few inches less than higher flows. On marginal pools, tail outs were much shallower. Deep waters— pools, deep outside bends and deep runs retained their fish holding character. Side channels on the other hand had suffered from the low flow losing all or most of their flow.
This side channel outlet has lost all its flow at 300CFS. Maybe some salvation due to beaver dams.
Here's the inflow to the side channel above. Completely dry
The lower flows tended to isolate and accentuate the better holding waters as well as highlight marginal holding areas. This is an opportunity all anglers should take--really explore your waters when they are low. A deep outside bend was still deep and a deep riffle bucket was still deep, while a marginal riffle corner that might produce fish at higher flows was now not very good water. One particular spot illustrates this well.
On a deep outside bend where the flow is strong, I’ve caught a lot of 19” plus rainbows and browns swinging a streamer tight to the bank on multiple trips. At higher flows the water line is pushed well into the grass and the only indication of structure are slight eddy like swirls. However, at the lower flow on this trip, an obviously undercut bank showed itself. Finding and pinpointing these kinds of productive holding waters at lower flows should inform your angling at higher flows.
A prominent undercut bank shows itself at lower flows. Several large browns and rainbows have been nailed at this spot even when the flows covered the undercut.
As long as river temps are within an acceptable range, exploring and angling during low flows can be very productive for future trips.
I noticed several things immediately. Riffles became longer stream wise but narrower overall. Some riffle buckets and corners had essentially disappeared while others had moved downstream slightly. Pools and deep runs appeared unchanged as the overall depth was probably just a few inches less than higher flows. On marginal pools, tail outs were much shallower. Deep waters— pools, deep outside bends and deep runs retained their fish holding character. Side channels on the other hand had suffered from the low flow losing all or most of their flow.
This side channel outlet has lost all its flow at 300CFS. Maybe some salvation due to beaver dams.
Here's the inflow to the side channel above. Completely dry
The lower flows tended to isolate and accentuate the better holding waters as well as highlight marginal holding areas. This is an opportunity all anglers should take--really explore your waters when they are low. A deep outside bend was still deep and a deep riffle bucket was still deep, while a marginal riffle corner that might produce fish at higher flows was now not very good water. One particular spot illustrates this well.
On a deep outside bend where the flow is strong, I’ve caught a lot of 19” plus rainbows and browns swinging a streamer tight to the bank on multiple trips. At higher flows the water line is pushed well into the grass and the only indication of structure are slight eddy like swirls. However, at the lower flow on this trip, an obviously undercut bank showed itself. Finding and pinpointing these kinds of productive holding waters at lower flows should inform your angling at higher flows.
A prominent undercut bank shows itself at lower flows. Several large browns and rainbows have been nailed at this spot even when the flows covered the undercut.
As long as river temps are within an acceptable range, exploring and angling during low flows can be very productive for future trips.
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