• Live flow (cubic feet per second) from USGS stream gauges, usually updated every 15 to 60 minutes.
• Each reading is placed within that gauge's own history for today's date, from decades of daily records. 50% means a typical flow for the date.
• Normal is 25–60%, good and lively 60–88%, high 88–97%, and flood 97% or above, or above 90% and rising fast.
• Rain in the next 3 days at the gauge warns that levels may rise.

Every river has its own runnable range, which depends on the section, your boat and your skill. Check a paddling guide such as American Whitewater for specific ranges, and never paddle a river in flood.