San Jacinto at SH 99 water level
Harris County Flood Warning System gauge 765 · San Jacinto · San Jacinto River watershed
water surface elevation, Oct 20, 2026 at 11:35 AM CDT · 15 minutes ago
- Below top of bank
- 24.4 ft
- Top of bank
- 81.0 ft
- Lowest since Sep 11
- 56.37 ft
- Highest since Sep 11
- 61.05 ft
- Usual range
- 56.47 to 60.79 ft
- Latest vs usual
- Within usual range
Of the 403 readings stored for this gauge, 27.5% were lower than the reading above. The closest this gauge has come to its top of bank in that period is 19.9 ft.
- Tsunami Warning — issued Oct 20, 2026 at 11:31 AM CDT, expires Oct 20, 2026 at 12:31 PM CDT.
TEST Tsunami Warning issued October 20 at 12:31PM EDT until October 20 at 1:31PM EDT by NWS National Tsunami Warning Center
Text as issued by NWS Houston/Galveston.
Last 7 days
Hourly averages of readings as published. The shaded band is this gauge's usual range: the middle 80% of its readings since Sep 11. This gauge reports about every 215 minutes, and only when its value changes, so gaps in the line are normal.
| Time | Level | Below top of bank |
|---|---|---|
| Oct 20, 11:00 AM CDT | 56.57 ft | 24.4 ft |
| Oct 20, 7:00 AM CDT | 56.56 ft | 24.4 ft |
| Oct 20, 3:00 AM CDT | 56.54 ft | 24.5 ft |
| Oct 19, 11:00 PM CDT | 56.53 ft | 24.5 ft |
| Oct 19, 7:00 PM CDT | 56.56 ft | 24.4 ft |
| Oct 19, 3:00 PM CDT | 56.59 ft | 24.4 ft |
| Oct 19, 11:00 AM CDT | 56.60 ft | 24.4 ft |
| Oct 19, 7:00 AM CDT | 56.57 ft | 24.4 ft |
| Oct 19, 3:00 AM CDT | 56.54 ft | 24.5 ft |
| Oct 18, 11:00 PM CDT | 56.53 ft | 24.5 ft |
How to read this gauge
The number above is an elevation, not a water depth. It is the height of the water surface above mean sea level, so SH 99 reads around 56 ft even when the channel is low. What matters is the distance to the top of bank: the elevation at which water reaches the top of the channel at this location. For this gauge that is 81.0 ft.
The bottom of the channel here sits at 56.0 ft, so the channel is roughly 25.0 ft deep at this crossing. Harris County publishes the top-of-bank figure with each reading; it is their reference, not an estimate made here.
Daily highs and lows since September 11, 2026
Download the readings
san-jacinto-at-sh-99.csv (CSV): every reading stored for this gauge since September 11, 2026, 403 rows, updated with this page. Columns: time in UTC, time in Central, water surface elevation, top of bank, and distance below top of bank, all in feet. The source and accuracy notes below apply to the file too.
Put this gauge on your website
HOAs, MUDs, civic clubs and schools can show this gauge's latest reading on their own site. Paste this HTML where it should appear; the card updates with this page. More gauges.
In past storms
| Storm | Peak | Peak time | Rise | Below bank at peak |
|---|---|---|---|---|
| October 1–2, 2026 | 61.05 ft | Oct 2, 2026 at 1:01 PM CDT | 4.6 ft | 19.9 ft |
Storms are runs of National Weather Service flood alerts for Harris County; each storm page lists every gauge's peak.
USGS gauge nearby
West Fork San Jacinto River above Lake Houston near Porter (USGS 08068090), less than 0.1 mi away, read 56.59 ft at Oct 20, 2026 at 10:45 AM CDT, 24.4 ft below the NWS minor flood stage of 81.0 ft. Its zero is at 0 ft NAVD88, so it also reports water surface elevation.
All gauges in this watershed: San Jacinto River watershed water levels.