Blanco River at San Marcos, TX
River level and flood forecast · Hays County
Normal6.8 ftas of Mon 3:45 PM
The river is 11.2 ft below flood stage (18 ft).
Flow: 0 cubic feet per second (USGS).
The last 7 days and the forecast
NWS forecast issued Sun, Dec 31, 6 PM. Forecasts change as rain falls and as upstream water arrives.
Flood stages
| Major flood stage | 30 ft |
| Moderate flood stage | 24 ft |
| Flood stage | 18 ft |
| Action stage | 13 ft |
| Record crest (May 24, 2015) | 43.1 ft |
What floods at each level
From the National Weather Service, highest first.
- 43 ftWater is several inches deep in the Walmart and CVS parking lots and other business in the region. Water surrounds the Balnco River Lodge apartments. Water into many homes and businesses along the river between I-35, SH 80 and River road. Water over teh Hwy 80 bridge at San Marcos
- 30 ftWater begins to enter many homes and businesses begin to have water entering the structures. More secondary and even primary raods become impassable for vehicles
- 24 ftLowest homes are threatened. Water beings to cut off secondary roads near the river
- 18 ftRoadways and low bridges along the river are flooded. Vehicles cannot pass. Livestock can be stranded.
- 13 ftOverbank conditions may cut off livestock and low bridges near the river
Highest crests on record
- 43.1 ft — May 24, 2015
- 42.56 ft — October 30, 2015
- 24.71 ft — October 14, 2021
- 24.14 ft — May 9, 2019
- 20.53 ft — May 4, 2019
Recent crests: 24.71 ft (October 14, 2021) · 24.14 ft (May 9, 2019) · 20.53 ft (May 4, 2019) · 10.93 ft (August 27, 2017) · 13.49 ft (April 11, 2017)
Up and down the river, and nearby
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (BSMT2); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.