SARA Load Reduction Tool

The SARA Load Reduction Tool was developed to allow users to determine the constituent load reductions needed to reach water quality standards in model reaches within a watershed through the application of BMPs.

The tool requires a working HSPF UCI file, corresponding input and output WDM files, and a BMP application specification file (referred to as “spec file” from here onwards). The spec file allows the user to define:

  • The list of landuses for BMP application, for each subbasin, and the percentage of available area for BMP implementation.
  • Screening levels for each constituent/reach combination, providing the targets the tool seeks to meet by comparing them to the modeled flow-weighted average concentrations.
  • A tolerance value is provided per constituent/reach combination allowing control of the “closeness” of the resulting concentration to its target.
  • Maximum BMP reduction factor for each constituent.
  • A flag for conducting log-transformation on concentration values for specified constituent/reach combinations.
  • A list of point sources to be considered as potential constituent reduction sources should regular land based BMP reductions does not meet the target screening levels.

The tool uses the specification file to apply BMPs in an upstream-to-downstream direction in the model watershed to reduce constituent loads to a reach. The end of run comes under 3 situations:

  • Maximum number of runs reached
  • No more BMP load reduction can be applied
  • All constituents in all reaches met their target screening levels

Users can carry out the whole process in either manual or auto-run mode. Report and template specification files can be generated using the tool as well.

AQUA TERRA Consultants created this tool for the San Antonio River Authority (SARA) and would like to acknowledge SARA and its contractor, Atkins, for their financial and technical support under the direction and management of Dr. Sheeba M. Thomas, Dr. Aarin Teague and Dr. Russell Persyn of SARA. SARA, Atkins and AQUA TERRA Consultants cannot assume responsibility for operation, output, interpretation or use of this software.


Download Instructions:

  1.  First, un-install any version of SARA Load Reduction Tool already installed. (Answer Yes if asked whether to remove shared components.)
  2. Download the new installer as .zzz
  3. Change the extension from .zzz to .zip
  4. Unzip to get the installer as .exe
  5. Run the installer .exe
  6. Running installer as Administrator may be required depending on security settings and the chosen install location.

Download SARA Load Reduction Tool 



AQUA TERRA Consultants (currently RESPEC), Decatur, Georgia developed this software and documentation under the sponsorship and technical direction of the San Antonio River Authority (SARA), LAN, and Atkins. Dr. Sheeba Thomas of SARA is the overall project manager for the development of this tool, Dr. Aarin Teague of SARA provides technical assistance and guidance. Dr. Yu-Chun Su of LAN develops the overall technical concepts and approaches, and conducts tool testing, modeling, and technical directions with Dr. Ka-Leung Lee of LAN. Chad Richards of Atkins helps with data collection and database development of the tool.  Dr. Tong Zhai, Paul Duda, Paul Hummel, Dr. Russell Persyn, and Mark Gray of RESPEC made up the software development team for this effort.

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SARA Water Quality Modeling Tools Disclaimer

The suite of Water Quality (WQ) Modeling Tools developed by the San Antonio River Authority (SARA) includes the WQ Modeling Standards, The Timeseries Utility Tool (TUT), The Load Reduction Tool (LRT), The Enhanced Best Management Practices (BMP) Tool and associated BMP Tool Database,  the Simulation Manager, and the BMP Processor/Reporter Tool.  These tools are provided as a courtesy by the San Antonio River Authority, in order to help SARA stakeholders and the general communities better evaluate WQ conditions and select/evaluate BMPs and Low Impact Development (LID).  The San Antonio River Authority does not represent or warrant that these tools are appropriate or will work properly for any specific project.  Use of the SARA Tools is at your own risk, and you agree that you will hold SARA and its tool development consultant team harmless from any losses you suffer related to the use of the SARA Tools.  Any modification or reuse of the SARA WQ Modeling Tools will require prior written permission from SARA.