About FloodWatch
Live river gauge levels and flood monitoring from national water services.
What this is
A flood is water covering land that is normally dry — from a river overtopping its banks, intense rain overwhelming drainage, snowmelt, or storm surge at the coast. FloodWatch focuses on river and stream gauges: instruments that measure how high and how fast the water is at thousands of points along waterways.
Each gauge reports a stage (water height) that FloodWatch compares against official flood thresholds — action, minor, moderate and major — to show, at a glance, which rivers are rising into dangerous territory and which are running normally.
Learn the basics
All articles →- 📏 How river gauges measure a floodStage vs. discharge, the action/minor/moderate/major thresholds, and why a small stream can be deadlier than a big river.
- 🌊 The main types of floodingFlash floods, river (riverine) floods, urban floods and coastal surge — different speeds, causes and dangers.
- 🚗 Why “turn around, don’t drown” worksThe physics of moving water, the danger of flooded roads, and how to act on a flood warning.
Flood safety
General guidance — follow your local emergency management and warnings first.
When a watch or warning is issued
- Move valuables and yourself to higher floors or ground; charge devices and follow official alerts.
- If you’re near a small stream or canyon, be ready to move uphill fast — flash floods give little warning.
Never enter floodwater
- Don’t drive or walk into water across a road; just 15 cm can knock you down and 30 cm can float a car.
- Stay away from storm drains, culverts and fast channels; water can hide washouts, debris and electrical hazards.
After the water recedes
- Avoid floodwater — it can be contaminated and electrified; don’t use wet appliances until checked.
- Return home only when authorities confirm it’s safe; watch for weakened roads and structures.
Data sources
- USGS Water Services (NWIS) — Real-time stream gauge stage and discharge across US waterways.
- NOAA / National Water Prediction Service — Flood categories, river forecasts and crest predictions.
Frequently asked
- What do the gauge colors mean?
- They show the highest flood category a gauge has reached — from normal through action, minor, moderate and major flooding — based on official thresholds set for that location’s local impacts.
- Is a rising gauge below flood stage safe?
- Not necessarily. A gauge climbing fast toward flood stage can become dangerous quickly, and small streams can flash-flood between readings. Watch the trend, not just the current level.
- How much water is dangerous to drive through?
- About 30 cm (one foot) of moving water can float many cars and 60 cm (two feet) sweeps away most vehicles. You can’t see if the road has washed out — turn around, don’t drown.
- Why does a river keep rising after the rain stops?
- Water takes time to drain off the land and travel downstream. Large rivers often crest a day or more after the rain ends, as runoff from upstream arrives.
⚠️ Important
FloodWatch is informational, not an official flood-warning system. Gauge data can be delayed or missing and thresholds vary by location. For life-safety decisions follow your national weather and water services and local emergency management.