How this site works

Sources, definitions and limits · figures below as of Oct 20, 2026 at 1:20 PM CDT

Gulf Coast Gauges republishes stream gauge readings for the Houston area as ordinary web pages, one per gauge, and keeps the history the original feeds do not. Every reading since September 11, 2026 is stored: 125,587 so far from 201 sensors on the Harris County Flood Warning System feed, alongside 70 USGS gauges. The pages are rebuilt from those stored readings every 15 minutes. No page is written individually: every number on every page is filled in from a stored reading or an official reference, by the same rules on every page.

Where the numbers come from

This site is not affiliated with any of these agencies, and their numbers are republished as they publish them. When a page shows a reading, it also shows the time that reading was taken, which is not the same as the time the page was built.

What the numbers mean

Harris County gauges: elevation and top of bank

A Harris County gauge reports the elevation of the water surface in feet: its height above a fixed reference level, not the depth of the water. That is why a creek can read 102 ft. The number that matters is the distance below top of bank: the gap between the water and the top of the channel at that crossing, using the top-of-bank elevation the county publishes with each reading. Top of bank is the county's reference, not an estimate made here, and it describes the channel at the gauge, not any street or house nearby.

USGS gauges: gage height and datum

A USGS gauge reports gage height: the water surface above the gauge's own zero point, its datum. For 68 of the 70 USGS gauges here that zero is set at 0 ft NAVD88, so the gage height is also an elevation. The others sit on a local zero; each gauge page says which. None of these numbers is a water depth.

Usual range

Each gauge's usual range is the middle 80% of its own stored readings (from the 10th to the 90th percentile). It is shaded on the charts so a reading can be read against what is normal for that gauge: tidal and lake gauges sit close to their banks every day, while some creeks are many feet below theirs even after rain. It reflects only the readings stored since September 11, 2026, so it will change as the record grows.

NWS flood stages

For 32 USGS gauges the National Weather Service publishes flood stages: action, minor, moderate and major, in the same feet as the gage height. They are shown only where the NWS's own current reading matched the USGS reading within half a foot when they were fetched, so the two are known to be on the same scale. They are the NWS's references for that location.

Records and annual peaks

USGS keeps the highest gage height of every water year (October to September). The site holds 2,897 such years, but compares today's readings with only 1,315 of them. Many gauges had their datum changed over the years, which moves every reading after it by a fixed amount; years from before a gauge's last datum change, or that USGS marks as measured at another site or datum, are shown on the charts but never ranked against today. "Record" on this site means the highest of the comparable years. The NWS keeps its own list of historic crests, which can differ, and the pages label which is which.

How a storm is defined

A storm is whatever the National Weather Service declared, not a judgement made here. Every flood alert issued for the Harris County forecast zones counts (coastal flood alerts excluded), and alerts that start within 24 hours of the previous one ending are one event. Each gauge's peak is its highest reading from 12 hours before the first alert to 48 hours after the last one ends, because large channels crest a day or more after the rain. "Came within 2 ft of top of bank" is a fixed threshold, the same for every storm. The storm archive lists 1 event so far, and each new one appears automatically.

Peak times are listed as recorded. Their order along a creek reflects where and when rain fell as well as water moving downstream, so the site does not present them as a travel time.

What this site does not do

• No forecasts. Nothing here predicts where water will go or how high it will get.
• No safety guidance. The site does not say whether any road, property or route is safe or passable, and a reading below top of bank is not an all-clear.
• No interpretation of alerts. NWS alerts are shown as issued; for the current list go to alerts.weather.gov, and for decisions about safety use official sources and local emergency management.

Limits worth knowing

• Gauges fail. A sensor can report late, stop, or report in error, and nothing here verifies readings independently. Pages say when a gauge's latest reading is more than a day old.
• County gauges report when the water changes, not on a timer: anywhere from every 15 minutes to every few hours. A gap in a chart is normal.
• Some sites are left out. Spillway, dam, gate and levee sites are not shown, because their top-of-bank figure is not a channel bank.
• History is short for county gauges. Their record here starts on September 11, 2026; USGS gauges carry decades.
• Recent USGS readings are provisional and can be revised after review.
• Times are Central, labelled CDT or CST for the date.

Contact

To report a reading that looks wrong, a page that is broken, or a question about the data or how it is shown: contact [at] gulfcoastgauges.com. This site can't answer questions about conditions at a particular property or road; for those, use the official sources above and local emergency management.

Using the data

Every gauge page has a CSV download of every reading stored for it, and every storm page a CSV of each gauge's peak. Any gauge can be put on another website with the embed widget. If you use the numbers, credit the agency that measured them (Harris County Flood Control District, USGS or NWS) and check its terms; this site only republishes them.