There is a lot to learn when you enter the world of fly fishing. Not to mention, there are a good handful of terms one should become familiar with. The one we will be talking about today is Cubic Feet Per Second, otherwise known as CFS. In sifting through the archives we found an older story that articulated the concept very well while providing valuable and relevant applications. This story is originally by former Trouts Marketing and Outfitting Manager, Kyle Wilkinson. This story dates back to 2015 however, all of the insight still rings true today. Without further ado, let us get into this week's Trouts Classic.
When starting out fly-fishing there is one fact that is impossible to get around or take a short-cut on, and that is the simple reality there is a lot to learn. In fact, talk to an accomplished fly angler and ask them what they love about fly fishing. You're likely to hear as part of their answer that "you're never done learning". I personally couldn't agree more and now- after twenty years of having a fly-rod in hand whenever possible- my desire to continue learning only grows by the day. It's something that I believe every fly-fisher sort of gets addicted to. To the beginner though, I fully realize that while all the intricacies of bug life, tippet diameter, and the benefits of low-stretch core fly lines may be cool and all, but in reality, just going out to the river and catching a damn trout or two seems much, much cooler. The learning process of fly-fishing has been simplified quite a bit over the years thanks to the internet, and information is more readily available than ever for anyone interested in diving into this sport. And aside from all the gadgets, gear, fly names, and dry fly/nymph debates and there is something else that can seem quite daunting to the newbie (or even just newbie to the state).....the CFS of our rivers and how this affects the fishing.
For those unfamiliar with this concept, I'll try to keep it as simple as possible. CFS- or 'cubic feet per second'- is a numeric term used to describe the amount of water currently flowing on a particular river. As you can probably guess, more CFS=more water. The way I like to think of CFS is to picture a basketball. This is approximately 1 foot x 1 foot x 1 foot, or 1 cubic foot. Now draw a line directly across the river. The number of basketballs passing across this line every second is your CFS measurement.
Now that we're familiar with this term, it still probably doesn't mean much without providing some frames of reference for what this looks like.
Below are some examples of our home waters and their 'normal' CFS levels- or perhaps better yet, CFS levels where you can expect to be comfortable (and hopefully successful) wade fishing. With any luck, this will provide some perspective so that when you hear "Dude! Cheesman is at 500 let's get in there!" or "Oh man, I really don't want to go to the Dream Stream when it's only at 55" you'll know that this means A) Cheesman is quite high. B) Dream Stream is on the low side. The figures listed below are what we here around the shop like to see these rivers flowing at. If you see flows on a particular river are below this, expect to find lower water and possibly tougher/more technical fishing. If you see CFS figures much higher, expect to find bigger than normal flows- which isn't always a bad thing- but may make wading much more difficult/dangerous in spots. Oh and yes, once you become familiar with these terms-like in the examples above- you'll likely find yourself dropping the 'cfs' when describing a river as well.
South Platte (Dream Stream/Elevenmile/Cheesman/Deckers)- 100cfs-300cfs
Blue River (Silverthorne)- 50cfs-200cfs
Clear Creek- 50cfs-150cfs
Bear Creek- 50cfs-150cfs
Arkansas (Canon City to Salida)- 300cfs-600cfs
Arkansas (Pueblo Tailwater)- 100cfs-300cfs
Frying Pan- 250-350cfs
Roaring Fork (Basalt to Carbondale)- 500-900cfs
Colorardo (Parshall)- 500-1000cfs
Colorado (Pumphouse)- 1000-2500cfs
Colorado (Glenwood Springs)- 2000-4000cfs
A few final thoughts on CFS.
1) When researching flows, there is more to it than just the instantaneous figure you get at the exact point in time you check. Pay attention to what the river has been doing to gauge how the river might be fishing. The keyword here is 'might'. (there are not guarantees or always in fishing obviously) What I mean by this though is how has the stability of the flows been? Is the river rising, falling, or stable? And for how many days?
2) In my opinion stable water conditions are always going to provide the most consistent and reliable fishing. If a river has been in flux (significantly rising/falling), I typically find that by day 2 or 3 after the river stabilizes (or hopefully returns to 'normal') the fishing will be best.
3) Given the choice, I'd always rather fish on rising water than on falling water. As a general rule- and one that you should keep in mind if you don't- Fish Follow The Water! On rising water, expect the fish to hit the banks picking off worms and other insects that are being washed into the river system. On falling water, expect a lot of fish to play the retreat game and head towards the middle of the river or first major drop-off's/shelves towards the middle. I will qualify my rising water preference by saying either A) low water conditions rising to more normal conditions or B) normal water conditions initially beginning to rise to slightly above normal. A perfect example of this was Cheesman Canyon during the beginning of the summer. When flows were on the rise the first couple of weeks (or even months), the fishing was INSANE! Every fish in the river was up shallow and eating worms being washed into the river. You'd literally be reeling in a fish and it would be puking worms. And then the water didn't quit rising...and then still didn't even after that. The 'Canyon instantly went from really good to really tough. I guess sometimes too much of a good thing really can be a bad thing.
When it comes to fly-fishing in Colorado we have A LOT of water to choose from and in my opinion, it's a pretty special thing that I can wake up here in Denver, grab some coffee, and find myself on any of these rivers a short time later. However, it doesn't matter how perfect your presentation may be, wade fishing any of these rivers, when flows are either extremely low or extremely high, can make for a potentially miserable experience. Thankfully we're here to help make sure this doesn't happen. Aside from keeping an eye on this Blog, be sure to keep your mouse-trigger finger ready on the River Report tab just a few spots to the left of the Blog tab. Stream flows for virtually every major river and stream in the state will be waiting for you!
As always, good luck out there, and please let us know how we can continue to make your time on the water more enjoyable and productive!