Editorial policy

Water Level Atlas publishes water levels measured by government agencies. This page explains what we publish, what we refuse to publish, and how we keep it accurate.

Where every number comes from

Every level, flow, temperature and flood status on this site is collected automatically from an official agency: for example the U.S. Geological Survey, the NOAA National Weather Service, the U.S. Army Corps of Engineers and the Bureau of Reclamation. Each page names its sources in the footer and links to the agency's own record. The full list, with each licence, is on our methodology and data sources page.

What we never do

• We never estimate or invent values. If something is not measured at a place, the page says "not measured here".
• We never publish a page without real data. A lake or river gets a page only when it has a live gauge and enough history to compare with.
• We never issue our own flood warnings or safety advice. Flood status is shown exactly as the official agency reports it, with a link to the agency's warning page.
• We never use generic filler text. The short text on each page is written from that place's own readings: today's level compared with its own records and its normal for the date.

How we compare with "normal"

"Normal for the date" is the middle half (25th to 75th percentile) of past values for that day of the year at the same gauge. Labels such as "below normal" or "much below normal" are a statistical description of the gauge's own history, not advice. The exact method is on the methodology page.

Provisional data

Recent readings are usually provisional: the agency may revise them after checking. We show them as the agency publishes them and update our copy when the agency does. Unusual one-off jumps are kept out of our "biggest change" lists, but the reading itself is shown as published.

Independence and money

We are an independent site, not a government agency, and no agency endorses us. The site is paid for by advertising and by affiliate links to products (see our affiliate disclosure). Advertisers and affiliate partners have no say over which places get pages or what the numbers show. Emails we send never contain affiliate links.

Corrections

If a number looks wrong, write to [email protected] with the page address. We check it against the agency record. If our copy or our method was wrong, we fix it and list the fix on our corrections page. If the agency's own data is wrong, we tell you how to report it to the agency.

Last reviewed October 21, 2026.