How we compute verdicts

Every verdict on this site is produced the same way: we compare a live gauge reading to a curated runnable range for that specific river section, then map the result to a plain-English band. Here is exactly how that works, and where it can be wrong.

Where the live data comes from

We read the U.S. Geological Survey (USGS) National Water Information System — the same public gauges USGS operates nationwide. We pull two things:

• Instantaneous values (updated roughly every 15–60 minutes): current discharge in cubic feet per second (CFS, parameter 00060) and gauge height in feet (parameter 00065). We cache these for 30 minutes.
• Daily values for the 7-day trend chart.

Each section page links directly to its USGS gauge so you can verify the raw numbers yourself. New to these units? See reading CFS and gauge height.

The runnable range

For each section we store a minimum runnable level and a maximum safe level, in CFS or gauge feet. Where a state water-trail program, park service, or paddling authority publishes a recommended range, we use it and cite the source on the page. Where none is published, we derive a conservative estimate and flag it clearly with an “estimated” badge. Estimated ranges lean cautious on purpose — they are a starting point, not gospel.

The four verdict bands

• 🟡 Too low — below the minimum runnable level. Expect scraping and walking.
• 🟢 Good to paddle — within the runnable range.
• 🟠 High — caution — above the maximum, up to 1.5× it. Pushy, cold, fewer eddies; experienced paddlers only.
• ⛔ Dangerous — more than 1.5× the maximum, or above the gauge's flood stage where known. Do not paddle.

The “rising fast” modifier

If flow has risen more than 30% in the last 24 hours, we append “rising fast” and never show a plain “good” verdict — a rapidly rising river is unpredictable and can keep climbing. A good level that's spiking is treated as caution.

What this cannot tell you

A flow number is one input, not the whole picture. It cannot detect a fallen tree across the channel, a newly formed strainer, water temperature, wind, an approaching storm, or your own skill and fatigue. Gauges can also lag reality or briefly go offline (we'll say “no reading” rather than guess). Treat every verdict as a first check, then verify on the ground. Read the safety guide before you launch.