To find the flow of the San Marcos River on USGS Texas river basins, find the Guadalupe River System. (USGS List of Texas River Basins) You can then find the flow of the Upper San Marcos and the flow of the Blanco River (it takes the water about four hours to get from Wimberley to Kyle and another four hours to get from Kyle to our camp). The flow at our camp is the combined flow of the San Marcos and the Blanco Rivers. The flow is given in cfs – which means cubic feet per second. The average flow of the San Marcos river is about 130 cfs. 100 cfs is pretty low. 500 cfs is very good flow (novices have to be very careful which section of river they run) and anything from 1000 cfs up is very high water for experts only. 10,000 cfs means the SMRR lower campground sites are underwater, 20,000 puts water in or very close to the bathhouse, and 30,000 means the whole SMRR camp is underwater. Tom Goynes, 2021
- USGS List of Texas River Basins
- San Marcos USGS Gauge below Spring Lake
- San Marcos USGS Gauge at Martindale, TX
- Blanco USGS Gauge above San Marcos confluence
- Blanco near Blanco, TX
- Blanco at Wimberley, TX