The San Antonio River Authority (SARA), Edwards Aquifer Authority (EAA), and Lockwood, Andrews & Newnam, Inc. (LAN) have conducted an Upper Cibolo Creek Watershed modeling effort using the Hydrological Simulation Program – FORTRAN (HSPF). The effort involved model development and calibration, including incorporating input from EAA related to the Edwards Aquifer zones. The Upper Cibolo Creek project is a continuation of SARA’s effort following the development of a suite of water quality modeling tools to allow quantitative water quality master planning and best management practice/low impact development prioritization of the San Antonio River Basin (SARB). These tools include the SARA Load Reduction Tool (LRT), the Enhanced BMP Tool, and the Log Pearson Type III (LP3) Tool. This presentation will cover the development and calibration of the Upper Cibolo Creek HSPF models, which was done in partnership with the Edwards Aquifer Authority, and the application of LRT toward quantitative water quality master planning.