One reading,
one comparison.

What it does

Enter a ZIP code. HighWater matches it to its Census tabulation-area centroid, finds river gauges within 45 miles that publish official flood thresholds, and builds the report around the nearest one that is currently reporting.

The report shows the current stage, the six-hour trend, the distance to the next flood threshold, the river forecast where one exists, and the National Weather Service impact statement describing what happens if the water reaches that threshold.

Where the numbers come from

Source	What it contributes
NOAA National Water Prediction Service	Gauge locations, observed stage, river forecasts, official action/minor/moderate/major flood stages, and the impact statements written by local forecast offices.
National Weather Service alerts	Flood watches, warnings and advisories active at your location.
FEMA OpenFEMA NFIP claims	Paid flood-insurance claims aggregated by ZIP code since 1978 for historical context, never individual claims.
US Census gazetteer	ZIP Code Tabulation Area centroids, used to locate you without a geocoding service.

The history pages

Alongside the live report, HighWater publishes the paid-claim record for every US ZIP code with at least 100 claims on file: what the National Flood Insurance Program has paid out there since 1978, which year was heaviest, which named storms drove it, and how much of it happened to properties the maps rated outside the high-risk zone.

Those pages are history, not forecast. A ZIP with no page has a shorter claim record, not a clean one, and claims only ever count insured properties whose owners filed and were paid.

There is no score

HighWater does not grade your risk or invent an index. The verdict is a direct comparison between one published number and another, and every figure behind it appears on the page. If the comparison cannot be made honestly, the report says so instead of guessing.

A small number of gauges publish thresholds that do not match the stage series attached to them. Rather than announce flooding on a river sitting at its normal level, HighWater detects that mismatch and declines to compare.

What it cannot tell you

• A river gauge describes one point on one river. Flash flooding, storm surge, dam releases, sewer backup and street drainage can flood a place no gauge shows rising.
• Large parts of the country have no gauge within 45 miles. An empty result means no gauge is watching, not that the area is safe.
• Gauge readings are provisional and can be wrong, delayed or missing. HighWater marks readings that have gone stale.
• Flood-insurance claims count only insured properties that filed and were paid, so they understate how often an area has actually flooded.
• Nothing here is a forecast of what will happen at your address, and nothing here is a warning.

In an emergency

Follow the National Weather Service and your local emergency officials. Do not drive or walk into floodwater. If you are told to evacuate, go.

Who makes it

HighWater is part of klepZ, an independent studio building focused tools from public data. No account, no paywall.