Ask a Salmon River guide what the river is like and the honest answer is, “It depends on the month.” The Salmon is the longest undammed river in the lower 48. Nobody upstream is opening or closing a dam, so what happens in the mountains each winter and spring decides what the river does all summer. That means the same stretch of whitewater near Riggins can feel like three different rivers between June and August.
Here is how Salmon River water levels change through the season, and what each one means for your rafting trip.
How we measure the river: CFS
Guides talk about flow in CFS, or cubic feet per second: how much water moves past a point every second. We keep an eye on the USGS gauge on the Salmon River at White Bird, just downstream of Riggins.
The number we care about most is 20,000 CFS. Historically, if you average out the data, that is about where high water starts. Above 20,000 you are in high water season. Below it, you are out of it.
Late May and June: high water
Snowmelt usually pushes the Salmon above 20,000 CFS from May through mid to late June. For years, the Fourth of July marked the end of high water. Lately it has been trending earlier, closer to June 20, depending on snowpack and spring rain.
How high can it get? Historically the river has peaked at 90,000 to 100,000 CFS. In 2023 it topped out around 75,000. Guides have a name for peak runoff in the 50,000 CFS range: the flipping 50s. You can probably guess why.
What high water means for your trip:
- Big, fast waves and powerful hydraulics. The Salmon is a big water river, so the rapids are driven by the force of the water more than by rocks.
- A quicker trip. Our half-day trip usually runs closer to 2 hours at high water because the river is moving so fast.
- A minimum age of 12 on the half-day trip during these conditions, and we mean it.
- Rapids look different. At high water, the first feature in Chair Rapid is a huge wave we call the whale’s tail, and guests fly right up and over it.
July: the sweet spot
As the snowmelt tapers off, flows drop through July. A lot of guides and guests consider July the best whitewater of the year. The rapids still have punch, the river warms up to around 70 degrees, and the beaches start to show.
July is a great month if you want real whitewater without the intensity of peak runoff, and it is when the canyon starts to feel like summer: hot days, cold drinks, and swimming in the eddies.
August: low water, warm water, big beaches
By August the Salmon is at low water. Some rapids mellow out to Class 2s and easy 3s, the sandy beaches are fully exposed, and the fishing holes get better. Our half-day trip usually stretches to about 3 hours because the river moves slower.
Low water does not mean boring. Some rapids actually get more interesting as the river drops:
- Tight Squeeze is more of a low water rapid. As flows drop, the waves get bigger, and the long calm pool below makes it a favorite swimming spot.
- Chair turns into a technical rock dodge, and it is still one of the wettest spots on the trip.
- Black Rock grows a punchy hole at lower water that surprises people who are not paying attention.
- Ruby Rapid, a Class 5 at high water, becomes a quiet boulder garden that is great for fishing and even hunting for garnets.
August is the easiest month to bring younger kids, and the warm water makes swimming part of the fun. Our guide to Salmon River family trips has more on planning with kids.
Fall: steelhead season
After rafting season winds down, the river settles into low, stable flows and the canyon walls take on fall color. From late October to mid-March, the Salmon around Riggins turns into steelhead water. See our guided fishing trips if you want to see the river in its quietest season.
Which water level is right for you?
- You want the biggest whitewater: late May and June. Everyone needs to be 12 or older on the half-day trip.
- You want the best all-around trip: July. Strong rapids, warming water, and beaches.
- You are bringing young kids or want lots of swimming: late July and August.
- You want to fish: smallmouth bass in summer, steelhead from late October to mid-March.
Because the Salmon is undammed, no two years are exactly alike. A big snow year can keep high water going into late June, and a dry year can bring low water early. We watch the gauge every day and plan each trip around the conditions.
Plan your trip around the river
Not sure which month or trip fits your group? Compare our rafting trips, read more about the best time to raft the Salmon River, or contact us. We are happy to tell you what the river is doing right now.
