The Guadalupe County Map Modernization project was initiated in October 2003, and entailed GIS-based hydrologic, hydraulic modeling updates, and re-mapping of the rivers and streams for that county. This project was one of the first studies under the FEMA Map Modernization Program that produced completely digital flood insurance study products for the nation. Digital Flood Insurance Rate Maps (DFIRMs) will replace the current FIRMs and will include database information related to the underlying base maps and technical data.

Phase 2 started in August 2004 and the hydrologic, hydraulic and mapping effort was completed in January 2006. March 2007 marked the end of the appeals period. All appeals were resolved and the updated FIRMs were published with an effective date of November 2, 2007.