The San Marcos River Is Running Low This Week, and Plaza Park's 40-Year Concert Season Ends Thursday

By 7:15 on a Thursday night in August, the lawn at Plaza Park is already staked out with blankets and folding chairs, and the smell of something fried is drifting over from the food tables near the Boy Scout troop selling drinks. Downtown San Marcos does this every Thursday from June into August, and most locals treat it like a fixture that will always be there next week. This week, two things are true that won't be true much longer: the river running past that same park is noticeably shallower than it's been most of the summer, and the free concert series that's filled this lawn since 1987 plays its final show of the year in three days, with the city still not saying who's on stage.

Neither of those facts shows up in the generic "things to do in San Marcos" roundups that rank for this town. They're the kind of thing you only know if you're paying attention to the calendar and the water level in the same week, which is exactly what this is.

The River Is Reading Lower Than It Looks

The San Marcos River has a reputation for being the reliable one. It's spring-fed out of San Marcos Springs, it holds a steady 72 degrees, and unlike the dam-controlled Guadalupe, it never actually runs dry. That reputation is true on average, but it isn't true every week, and this is one of the weeks where it isn't.

Normal flow on the San Marcos River generally runs between 150 and 300 cubic feet per second. A recent reading on the live tracker at Floating Texas put the river at roughly 96 cfs, which is well under that normal range and noticeably lower than what the Guadalupe and Frio were reading that same day. It's not a crisis, and the outfitters weren't calling it dangerous. But it's the difference between a float where you drift the whole way and one where you're occasionally standing up to walk your tube over exposed rock, which is exactly the kind of thing tubing outfitters warn about during low-water stretches.

That matters for a practical reason: it changes which stretch of the river is worth your afternoon.

• San Marcos Lions Club Tube Rental floats the stretch through the middle of downtown. It's a non-profit tube rental operation that has served San Marcos since 1978, with all proceeds supporting local community programs. Depending on water levels, this float runs about 45 minutes to an hour. Pricing is $25 per tube with unlimited shuttle, or $15 per person if you bring your own tube.
• Don's Fish Camp and Texas State Tubes put in downstream through Martindale, about 12 miles southeast of town, for a longer, quieter float through cypress-lined banks. These are closer to a three-hour float. Texas State Tubes runs from the first hot Saturday in March through the last Saturday in September.

When flow is closer to normal, the longer Martindale float is the better use of an afternoon. When it's sitting around 96 cfs, the shorter downtown stretch through the Lions Club put-in is the safer bet if your goal is an actual float and not a rock-walking hike with a tube attached to your ankle. Check the number before you decide, not after you've already driven to Martindale.

The river rules haven't changed regardless of flow. Glass and styrofoam, even as coolers, aren't allowed in city parks. Life jackets are required for children under 6. Cans are fine, glass isn't, and that's true whether the gauge reads 96 or 250.

Forty Summers of Plaza Park Come Down to One More Thursday

Summer in the Park is celebrating 40 years of free concerts and entertainment for the San Marcos community in 2026. It's run in partnership with the City of San Marcos and local sponsors like the San Marcos Chamber of Commerce, every Thursday night from June to the second week of August, since 1987. This is the week that second week of August arrives.

Here's the full 2026 lineup, and where it stands as of today:

That lineup and its dates come straight from the city's own event listing. The closer, this Thursday, is still marked TBD. That's not a formatting oversight. It means the season's last show hasn't been locked in with days to go, which is worth knowing if you were planning to skip this one and catch "whoever's better" next week. There is no next week. After August 13, the lawn at Plaza Park goes quiet until next June.

Shows start at 7:30 p.m., and pets are welcome as long as they're leashed. Parking is available at a public lot near the San Marcos Lions Club Tube Rental, which means the same stretch of river you might float earlier in the day is also where you'll park that night. If it rains, the rain site is the San Marcos Activity Center.

What To Actually Do With This Week

If you're weighing a normal weekend against this particular one, here's what separates the two:

1. Check the flow before you commit to a route. A quick look at a live river tracker in the morning tells you whether the Martindale float is worth the drive or whether you're better off sticking to the shorter downtown stretch through the Lions Club put-in.
2. Go Thursday, not "sometime this month." The 40th season of Summer in the Park closes this week. There's no rain check on a tradition that only runs June through the second week of August.
3. Park once, use it twice. The same lot near the Lions Club Tube Rental works for an afternoon float and an evening concert if you're making a full day of it.
4. Bring cans, not glass, and a leash if the dog's coming. The rules haven't loosened just because it's the last week.
5. Don't assume the headliner. If the closer being unannounced bothers you, that's exactly why you show up rather than wait for the lineup to firm up online.

None of this is really about the river or the concert series on their own. It's about the fact that San Marcos runs on a summer clock that most people only notice once it's already ticked past them. The flow drops quietly. The concert series ends on a fixed date whether or not the closing act is locked in yet. Neither one sends a reminder.

That's the actual shape of a San Marcos August: not one long undifferentiated stretch of "summer stuff," but a handful of specific, checkable windows that close on their own schedule. This is one of them.

If you've lived here long enough to have a favorite tubing route or a regular spot on the Plaza Park lawn, you already know how fast this town's rhythm resets once the concerts stop and the river starts running its fall pattern. And if you're ever curious what that same rhythm has done to what your San Marcos home is worth after another summer of people wanting exactly this, the team at Olive Fox Properties is easy to reach. Get a Free Home Valuation whenever you're ready, no pressure attached, same as the river. It'll still be there next week either way.