Why this exists
Most float-time advice is a guidebook number: “figure 3 to 4 hours.” That number assumes some flow nobody wrote down. The same 9-mile stretch can take two and a half hours in June runoff and twice that in a bony September. Add a tube, a cooler, or a few stops to fish, and the guess drifts even further.
Float ETA starts from today's water instead. Every river on the site is tied to a real USGS streamgage, so the estimate changes when the river changes.
How the estimate works
- Live flow. We read the latest discharge (cubic feet per second) and, where available, water temperature from the USGS Water Services API each time you load a river.
- Flow to speed. Each river has a typical raft drift speed at a reference flow. Speed rises with discharge following the hydraulic-geometry relationship v ∝ Q0.34, so doubling the flow makes the boat about 27% faster, not twice as fast.
- Your craft. Paddled kayaks and canoes run about 20% faster than a drifting raft. Tubes run about 28% slower. Paddleboards are close to a raft.
- Fishing. Add your expected total stop and fishing time in minutes.
- Daylight. We calculate sunset at the put-in and tell you the latest sensible launch time, or when you'll reach the take-out if you enter a put-in time.
- Weather. Air temperature, wind, rain chance, and UV for the put-in come from Open-Meteo.
What it can't tell you
Float ETA is a planning tool, not a safety tool. It doesn't know about the tree that fell across the channel last night, a closed access site, wind on a slow stretch, or how long your group spends on a gravel bar. Mileages are approximate. Wood, ice, and high water can turn an easy stretch into a dangerous one. Scout what you can't see, wear a PFD, and check the state agency for closures.
That's also why the river reports section exists. If you see a strainer, fence, or diversion, post it so the next boat knows. Reports expire after 45 days unless someone confirms the hazard is still there.
Where the data comes from
- Streamflow and water temperature: USGS Water Services
- Weather: Open-Meteo
- Sunset: calculated on the page from the put-in's latitude and longitude
- Rivers and stretches: put together from public access sites and state boating information
Where we float
Float ETA covers Montana, Idaho, and Oregon, with more western states on the way. Each state page lists every river and stretch we track.
Get in touch
Wrong mileage, a missing take-out, or a river we should add? Send a note on the contact page. Corrections from people who float these rivers make the site better for everyone.