San Marcos River at San Marcos
Texas · Tubing & floating
Measured at USGS 08170500 — San Marcos Rv at San Marcos, TX · NWS forecast point SRUT2
Reading taken Jul 28, 11:45 PM UTC
Running thin — a slow, scrapey float
At 132 CFS, this gauge is running 79% of normal for late July — below the 167 CFS median USGS has recorded for this date across 31 years of record (1995–2026).
Data-derived guidance from USGS and NWS published values — not official advice, and not a safety assessment.
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12 months of flow at San Marcos
Daily values from USGS gauge 08170500. Provisional data, subject to revision.
Highest crests on record at San Marcos
| Stage | Flow | Date |
|---|---|---|
| 21.29 ft | 21,500 CFS | Oct 17, 1998 |
| 10.77 ft | 2,470 CFS | Jul 8, 2002 |
Historical crests published by the National Weather Service for this gauge.
About San Marcos River at San Marcos
This gauge measures San Marcos River at San Marcos, Texas — the reading paddlers, anglers and outfitters on this stretch check before committing to a shuttle.
Spring-fed, floated year-round; City Park and Rio Vista.
Raw CFS means little on its own, so every reading on this page is shown against the USGS median for the same calendar day — 167 CFS for late July, from 31 years of record.
San Marcos River at San Marcos — common questions
What is the current flow on San Marcos River at San Marcos?
As of the last reading on this page, San Marcos River at San Marcos was running 132 CFS at a gage height of 4.09 ft, or 79% of the USGS median for this date. The number updates automatically from USGS gauge 08170500, which reports every 15 to 60 minutes.
Is that high or low for this time of year?
The USGS median flow for late July at this gauge is 167 CFS, calculated from 31 years of record (1995–2026). Comparing today's reading against that median is the only way a raw CFS number tells you anything — 200 CFS is a drought on one river and a flood on another.
How often does this reading update?
USGS transmits from this gauge every 15 to 60 minutes. This page bakes in the most recent reading when it is rebuilt, then refreshes live from USGS when you open it. Readings are provisional and subject to revision by USGS.
What flow is good for tubing San Marcos River?
riverlvl does not publish a recommended tubing range — that call belongs to the outfitters and the local authorities who know this stretch. What this page gives you is the objective input: today's flow, the seasonal median for the same date, and where the reading sits in the 12-month record. Local outfitters generally publish their own cutoffs, and they close when the river is up.
Does rain upstream change this reading quickly?
Yes. This is a free-flowing gauge, so it responds directly to rain in the basin upstream. Flashy rises of several feet in a few hours are normal on rivers like this after a heavy storm, which is why the reading is worth checking the morning you go.
What does gage height mean versus CFS?
Gage height is how high the water surface is above the gauge's own zero point, in feet — a local measure, not depth and not elevation. CFS is cubic feet per second, the volume of water moving past the gauge. Flood stages are set in gage height; float and paddling conditions are usually discussed in CFS.