Understanding CFS and Water Levels
The most important and often overlooked acronym in the fly fishing dictionary is CFS, Cubic Feet per Second. This term is used to measure flow or discharge of rivers and streams. Many say they understand, but it can sometimes be tricky to wrap your head around. I know it was for me when I was first starting out. Water levels/flow, or CFS can give insight into how the fishing will be, but most importantly, it will help us stay safe. Here in the southeast, we have had some large tropical storms roll through this past fall. I have witnessed novice anglers taking big risks wading in water they had no business being in. I get it, we all love to fish! I never want to let a little rain ruin my Saturday; the only day some of us get to fish each week. With both safety and big fish in mind, we will discuss when it’s good to hit the water and when it is time to throw in the towel.
So what is Cubic Feet per Second?
To understand CFS, we need to understand that we are measuring the speed a specific amount of water is passing by a fixed point. To break it down a little more, picture a 1ft x 1ft box filled with water. That is one cubit foot. Now, draw a line across the river. The amount of square foot boxes that cross this line per second gives you the CFS measurement. In some streams, that number can be low, in the hundreds and even double digits. In large western rivers, measurements can reach tens of thousands. That is some powerful water. Each river is unique. For example, 1000 cfs here in North Carolina is considered to be high water whereas out west, that would just be a trickle compared to their mighty waters. If you showed me a CFS flow chart to a random stream in a state I was unfamiliar with, it would be difficult to have an understanding of the river. As anglers, it is a good practice to do a little research on streams we have never fished. Let’s check out this flow chart below.