Atlas 14 ~New~

The National Oceanic and Atmospheric Administration (NOAA) reassessed historic rainfall intensities for Texas with results published as NOAA Atlas 14 Precipitation-Frequency Atlas of the United States, Volume 11 (Atlas 14).  Atlas 14 results show the San Marcos area to be in one of the significantly impacted areas in the State of Texas.  There is more rain to account for than originally considered in the design of stormwater and flood control infrastructure which means larger infrastructure and increased cost.

The City of San Marcos (City) is incorporating Atlas 14 rainfall data to more accurately assess flood risk.  We have prepared an Atlas 14 Reference Guide to provide Atlas 14 information including what is Atlas 14, how San Marcos is impacted, and common Atlas 14 related questions.  In addition we are updating our Stormwater Technical Manual to adopt new Atlas 14 rainfall data.   Changes to the manual reflecting Atlas 14 can be found in the Stormwater Technical Manual Atlas 14 Changes document.

Review and Comment Period

The City accepted comments related to the proposed Stormwater Technical Manual Atlas 14 Changes from March 1 to March 31, 2020 with the goal of implementing changes by June 1, 2020.   Any comments or questions can be sent to