What is CFS and What Does It Mean for My Raft Trip?

By Molly   •   January 30, 2018

What is CFS?

Have you heard raft guides and river folks throw around the term ‘CFS’ but aren’t sure what that means? So what is CFS. CFS stands for cubic feet per second which is a unit of measurement referring to the volume and speed of water flow. So basically, if a river has a high CFS that means the water is flowing faster resulting in larger rapids. With this said, CFS is very important to be aware of as different levels will give you different experiences on the water. A river is considered having high water when the CFS is 3,000 and above and low water is around 200/300 CFS. If the river is low, your rafting trip might be more mellow and have less intense waves. Gauges are installed on rivers in order to measure the CFS and that information can be found on city water data sites.


Here at Mild to Wild, the classes of CFS are defined as follows:


Class I: “moving water” will let you comfortably float down the river.

Class II: “splashes” will get your legs wet just over the side of the boat.

Class III: “wet and fun” rapids will get you soaked, head to foot!

Class IV: “big drops” will jump-start your heart as you paddle through the intense whitewater.

Class V: “violent rapids” will really get your adrenaline pumping and often have to be portaged.

Class VI: “impassable whitewater” means no one has rafted that section and lived to tell.

Mild to Wild Rivers and Their CFS Ranges

Continue reading to find out what the CFS ranges you’ll encounter with the rivers Mild to Wild rafts. This includes everything from class I to class V rapids.

Lower Animas

The Lower Animas is a relatively mellow trip that includes class I, II, and III where the class III rapid is only the man-made rapids at Santa Rita Park. During High Water, at 3,800cfs and above, we don’t raft the whitewater park and put in below Santa Rita.

Durango Rapid - Durango Colorado - Mild to Wild Rafting
Mild to Wild going through the Smelter rapid near Santa Rita park

Upper Animas

The Upper Animas has several sections with varying classes of rapids:


  • Silverton Section: Class III, IV, V


  • Needleton Section: Class III, IV, (1)V


  • Rockwood: Class II, III, IV(+)


So these parts of the Animas River are more intense than the Lower, going all the way up to a class V.

San Miguel River

This river out of Telluride, will give you a moderate level rafting trip with class II & III during high and low water. You’ll surely enjoy the splashes and head-to-toe soak you will get with this river!

San Miguel Rapids - Telluride - Mild to Wild Rafting

Colorado River

The Colorado is a very mellow and family friendly river that is class I & II (high and low water). Join Mild to Wild in Moab to float down this relaxing and peaceful river while still getting a little wet!

Moab Utah Whitewater Rafting-Colorado River-Mild to Wild Rafting

Lower Piedra

With class III, IV, and V rapids, the lower part of Piedra is considered a high level for rafting. If the water is too high, we will portage rapids. Get ready to get that adrenaline pumping with these exhilarating waves!


Upper Piedra

The Upper Piedra has class II, III, IV (high and low water) so it is slightly less rigorous as the lower but will still get you soaked and have you conquering some rapids!


Salt River

We have some variance between day trips and multi-day trips on the Salt River:

  • Day Trips: Class II, III
  • Multi-days: Class II, III, IV

These trips have the same class of rapids for high and low water.

White Water Rafting Salt River - Phoenix - Mild to Wild Rafting

Verde River

Arizona’s designated wild and scenic river out of Sedona contains class II &III rapids. Enjoy 1 and 2-day trips down this beautiful canyon!


More Reading:

Common Concerns on a Rafting Trip

6 Things You Didn’t Know About Moab, UT

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