Water Works: The Heat is On

by Bob Luck
Last Thursday, Mike Miller and I decided to fish the lower Kinni before the arrival of the latest heat dome.  We got to the stream at 7:30 and I measured the air temp at 68 and water temp at 61.  After a good morning, we decided to call it quits at 2 pm.  On a whim, I stuck my digital thermometer into the water and saw that the temperature had climbed to 68, the point at which TU recommends stopping catch-and-release fishing due to the stress caused by low water oxygen levels.  The air temp at that point was “only” 83 degrees, but it was a sunny morning, and I suspect that solar radiation was heating the dark rocks in the streambed which were in turn heating up the water.  And heating up the reservoir behind the Junction Falls dam, too.  We really need to get that dam out of there!
If the lower Kinni was 68 on a moderately warm day, you may be wondering how it is faring during the current heat wave. 
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​I haven’t been over to the Kinni this week so I can’t tell you for sure, but I do know that I measured the water temp at 73F in late June of 2022, at the end of a hot week.  The Rush suffers, too:  the water temp was 74F on a June evening in late June 2021 at the Ellsworth Rod & Gun Club.  Both those readings were taken in the early evening, which is when I suspect stream temps hit their daily high point.
Needless to say, I don’t recommend that you fish the Kinni or Rush any time after noon until the air temperatures come down substantially.  That doesn’t mean you shouldn’t fish!  The trico hatch has started on the Rush and when I checked the water temp a couple mornings ago it was a comfortable 60F.  If you prefer fishing later in the day, try a smaller stream.  Yesterday I fished a small meadow stream in Western Wisconsin from 11 am to 4 pm.  The water temp was 61 when I started and 66 when I finished.  I spent most of my time in the streambed, wading slowly upstream and casting a hopper.  I waded wet and stayed plenty cool, despite air temperatures in the 90s.  I spooked thousands of fish (I am not exaggerating), but I still had steady action, and didn’t seem to catch any more fish by creeping along the bank, which was far less comfortable.
If you do fish, I recommend using a digital meat thermometer.  It takes accurate temperatures instantly, and it has really improved my grilling performance, too!