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Summer Trout: Beating the Heat

by Philip Monahan

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Question: We’ve had a very hot summer so far in the Northeast, which has led to low, warm water in trout streams. Last time I took the temperature of my home river, it was 72 degrees, and I couldn’t find any fish. Where are the best places in a river to catch trout when the temperature rises into the low 70s?

Bob C., Concord, NH

Trout Fishingphoto by Colynn

Answer: The best place to look is in a different stream, one with cooler water, which usually means higher elevation mountain streams. Although many guidebooks say that brown trout can “tolerate” temperatures in the low 70s, that doesn’t necessarily mean that it’s good for them. When the water gets that warm, there’s less dissolved oxygen, the fish have less energy, and any undue stress might be the deciding factor in whether the fish survives under suboptimal conditions. So, just because we can fish then doesn’t mean we should.

Last week, my friend Doug drove three hours from his home near Boston to fish his beloved Battenkill in Vermont. When he arrived, he checked the water temperature and found it to be 72 (just like yours). Deciding that the health of the trout was more important than his angling enjoyment, he chose not to fish the river at all—six hours of driving be damned. Luckily, you can’t swing a cat around here without hitting a cool brook-trout stream coming out of the mountains, so all was not lost.

Where you draw the line is up to you, of course. For me, it’s 70 degrees. That’s probably a couple degrees lower than what a fish biologist would say is an acceptable temperature, but I’d rather err on the side of caution. And just because you can’t cast for trout doesn’t mean you have to do something else like (horror!) play golf. Keep in mind that there are plenty of warmwater species that will eat a fly and give you that tug on the line you crave. And if you’ve ever caught a trout in really warm water, you’ll know that the fight is nothing to write home about and it’s tough to revive the fish when you release it.

Ultimately, we have to balance the importance of our angling enjoyment with the health of the trout. I don’t know any fly fishermen who set out to do harm to their quarry. If we take care of the trout when water conditions are bad, we ensure better fishing when the situation improves.

MidCurrent Fly Fishing
Phil Monahan is a former Alaskan guide and was the long-time editor of American Angler magazine. He's now a columnist for MidCurrent and writes and edits the fly-fishing blog at You can email your fly fishing questions to us at
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  • Norm

    I grew up in Andover, NH not that far north of Concord. If you are willing to fish small wooded
    streams for wild brook trout there are lots of places with cooler water not too
    far away.

    Water temperatures rise rather quickly as the day progresses
    so fish early in the day. Also, since
    the amount of oxygen, water can hold increases with increased temperatures
    concentrates your fishing to the areas just below riffles, a streams natural aerator. We were asked by a Wyoming rancher to “test
    fish” a section of the Little Snake River this summer. Even thought it was early in July the water
    was low and just marginally safe temperature wise. The fish were concentrated in the runs and
    transitions into the pools just below strong riffles.

  • Norm

    It should have read “decreases with increased temperature”

  • Rick

    I am on the coast of Massachussetts and many of our streams now are too warm for trout (sea-run and stocked). If the tug is your drug, there is nothing like a big bass on your line to get the adrenaline running!