Trouts Journal

Low Flows on the South Platte || A Guide to Understanding Water Temperatures & Trout

Ivan Orsic / Jun 4, 2020

You may have noticed that flows below Cheesman Reservoir dropped pretty significantly last week, dropping from nearly 400 cfs to 75 cfs. That's over 200 cfs below-average flows for this time of year. With Cheesman Reservoir currently sitting at 61% capacity, we're looking at low flows below Cheesman Reservoir for a little while. Frankly, this is a bit unexpected as we had a strong snowpack entering the beginning of spring. Our good friend Pat Dorsey put together an incredibly detailed rundown of why we're seeing these low flows on the South Platte below Cheesman.

Combine the aforementioned low flows with warm ambient air temperatures over the past couple of weeks, water temperatures below Deckers are starting to climb into the 60s in the afternoon hours. This isn't the case for Cheesman Canyon, where water temperatures are starting off in the 40s and rising into the 50s by the afternoon.

With that in mind, we wanted to revisit Water Temperatures - When to Fish & When Not To. As a general rule, trout are happiest when water temperatures are below 65ºF. Anytime water temperatures in moving water hit 67ºF, STOP FISHING. When water temperatures in moving water are between 65-66ºF we recommend getting out early in the morning and not fishing through the heat of the day. We also recommend "ROPING UP" and using heavier tippet so as to reduce the amount of time you fight a fish. This helps to reduce fish mortality.

When we see elevated temperatures, this is a great opportunity to fish higher up in the drainage, as well as stillwaters, local warm water fisheries, the high country, and when flows round into shape, your favorite freestones.

As we see these extended low flows along the South Platte, we encourage everyone to get out early, rope up, and avoid fishing when the water temps hit 67ºF. If you're looking for a great on the water thermometer, look no further than the Fishpond Swift Current Thermometer.

Check out the graphic below for a quick rundown on what temperatures are safe to fish for trout.

Get Prepped for Low Water

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