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Salmon River Whitewater Difficulty

As is the case on all rivers, whitewater difficulty varies based on water levels.  Since the Salmon River is a free-flowing river with no dams, levels are dependent on weather conditions and fluctuate throughout the season. 

High Water:
May- June
Flows vary from 10,000 to 100,000 cfs (most years the river peaks around 40-50,000)

As spring weather warms up the snow in Idaho’s high country begins to melt.  Generally flows on the Salmon rise gradually and drop gradually, but a weather event such as warm rain on snow will cause a much more sudden change.  The pool and drop nature that most rafters and paddlers expect on the Salmon River remain, even at higher flows.  However, at flows about 20,000 cfs the pools will still have current in them and little or no paddling or rowing is required to get downstream between the rapids. During this time of year water temperatures on the Salmon River are cold, ranging between 45 and 55 degrees.  Some of the rapids are washed out by higher flows, while others get bigger waves.  The biggest rapid of concern is the Devil’s Slide.  At flows over 25,000 cfs it has huge, powerful waves that break in an irregular fashion.  There is very little room to maneuver between the canyon walls and it is not uncommon for rafts to flip at these levels.  Some people actually attach two or three rafts together to form a larger craft, but this is a technique best left to experienced guides

Medium Water:
Flows vary from 10,000 to 30,000 cfs in the first couple of weeks of July, dropping gradually as the summer continues.  By mid-August flows will range from 3000 to 5000 cfs on most years.

As summer progresses, water levels drop.  The large waves of high water become smaller, but still impressive.  More rocks begin to appear and the rapids become more technical.  Since the river is generally a class III trip, most rapids are still fairly easy to “read and run” meaning you can scout from your boat and read the water without having to scout.  However, many boaters will want to scout Snowhole and China rapids on the Salmon River.  Most rafters and paddlers raft the Salmon River starting around mid-July, after the high water period is over.  Hotter days also make this a more popular time of year for Salmon River rafting trips.

Low water:
This section of the Salmon River is never too low to float.  The record low on the river was during a drought year and was around 1800 cfs.  By the standards of many rivers, this is still a lot of water.  Most years the lowest flows on the Salmon River are around 3000 cfs.  Low water is typically very clear and the fishing improves.  Curiously, the Salmon usually reaches its lowest flows in latter August and then stabilizes into September and the rest of the winter.

Real-Time River Flows: USGS River Flows

Idaho Snow Survey: National Resources Conservation Service


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