Basics
How to Read CFS and Gauge Height (Plain English)
Two numbers show up on almost every river gauge: CFS (discharge) and gauge height (stage). If you understand these two, you can read any USGS gauge in the country. Here’s the plain-English version.
CFS: how much water is moving
CFS stands for cubic feet per second — the volume of water flowing past a fixed point every second. Picture a cubic foot of water as roughly a basketball. At 300 CFS, about 300 basketballs of water rush past you each second; at 3,000 CFS, ten times that. CFS is the single best number for “how much river is there right now,” because it measures actual volume regardless of how wide or deep the channel is.
Because it’s a true volume, CFS is what we compare against each section’s runnable range. Below the minimum, there isn’t enough water and you’ll scrape and drag. Within range, it floats nicely. Well above the maximum, the same channel turns fast, cold and pushy.
Gauge height: how high the water is
Gauge height (or “stage”) is simply how many feet deep the water is at the gauge, measured against a fixed reference. It rises and falls with flow, so it’s a great at-a-glance signal of “rising or dropping.” But a gauge-height number only means something on that specific gauge — 4 feet on a wide, shallow river is a completely different amount of water than 4 feet in a narrow gorge.
Some gauges only report stage (feet), not discharge. For those sections we use published feet-based ranges from water-trail programs. For most sections, though, we lead with CFS.
Reading the two together
Use CFS to judge whether the level is runnable, and use gauge height (and the 7-day trend) to judge the direction. A river that’s in range but climbing fast deserves more caution than one holding steady — which is exactly why our verdict flags a river that has risen more than 30% in 24 hours as “rising fast.”
Putting it to work
On any section page we show the current CFS or gauge height, the runnable range, and a 7-day trend chart with the runnable band shaded, so you can see at a glance whether today’s reading sits below, inside, or above the sweet spot. Want the raw source? Every page links straight to the USGS gauge — here’s how to read a USGS gauge page yourself.
Next, learn why the same CFS means different things on different rivers, and always review the safety guide before you launch.
Frequently asked
What does CFS mean?
CFS is cubic feet per second — the volume of water passing a point each second. One cubic foot is about the size of a basketball, so 500 CFS means roughly 500 basketballs of water flowing past you every second.
Is CFS or gauge height more useful?
For comparing runnable levels between rivers, CFS is usually more meaningful because it measures actual volume. Gauge height (feet) is a stage reading tied to that one gauge and its channel shape, so a “good” foot-value on one river means nothing on another.
What is a good CFS for kayaking?
It depends entirely on the river and section — a small creek might be perfect at 150 CFS and dangerous at 1,500, while a big river needs thousands to float at all. Always check the specific section’s runnable range.
Remember: verdicts and guides are informational only. Always scout, wear a PFD, and check local conditions. Read the safety guide.