SacCalc: The Hydrologic Calculator

The Sacramento County Hydrologic Calculator, SacCalc, is a Microsoft Windows application that makes it easy to comply with the Sacramento County hydrology standards. It replaces the DOS-based computer program SACPRE. David Ford Consulting Engineers, Inc. developed SacCalc under contract with the County.

An updated version of the calculator program that runs on Windows 7 is complete and ready for use. You can download the program here.


SacCalc has the following features to help you complete your hydrologic design:

  • Graphical user interfaces for watershed layout and design storm selection.
  • Wizards that guide you in specifying basin parameters such as land use and lag computation components.
  • Diversions and return flows, detention ponds with pumps.
  • The Nolte method. Same SacCalc project file can contain both HEC-1 and Nolte method specifications.
  • XML file format, output to HEC-DSS, and COM API for export to and customization by other programs: your hard work isn't locked up for SacCalc's use only.
  • HEC-1L: extra-large array version of HEC-1.
  • Comprehensive Help file that includes guidance from the Hydrology Standards and links to documents on the County's Web site.
  • Developed and tested by registered professional engineers with practical design experience.


SacCalc runs on computers meeting current office standards. Specifically:

  • An Intel x86-type processor PC with Microsoft Windows XP, Windows 7, or Windows 10. This updated version of SacCalc has not been tested with Windows NT 4.0 or Windows 2000. SacCalc is not supported (and should not be run) on Windows 3.1, NT, 95, 98, or non-x86 platforms. Running SacCalc on unsupported operating systems could crash your computer.
  • Older or preliminary versions of SacCalc must be removed (uninstalled).


Download SacCalc software here. Simply download the following installation packages by clicking the hyperlinks. If your computer operates on a network, you may need "Administrator privileges" to do this.

  • SacCalc version (9/30/11) installation disc Zip file. Simply unzip this file to a temporary folder and run SacCalc_setup.exe.
  • Once SacCalc is installed, copy the HecLib.dll file from the installation disc Zip file above to the SacCalc system folder. When using the default installation folders this is typically C:\Program Files\Ford\SacCalc\system\.
  • (Optional) HEC-DSSVue, a program for viewing plots of SacCalc flow hydrographs and other HEC-1 output time series. The program can be downloaded at​.

Sample files: The following downloads are not executable files. They are example SacCalc project files. Download them to a folder on your computer by right clicking the link and choosing Save Target As, then double-click them to open them in SacCalc.​


SacCalc has been under extensive development and testing since 2001, and all bugs identified to date have been resolved. If you suspect you’ve discovered a bug, please take a few minutes to rule out other issues by performing the following steps before notifying us.

Please review applicable sections of the Drainage Manual. Then, if you are using the HEC-1 method, please review the HEC-1 input file generated by SacCalc, especially t​he comment cards that SacCalc includes. Numerous consultants offer HEC-1 support and HEC-1 manuals for purchase. Run a report of your SacCalc project and look over it carefully; perhaps you entered the wrong value. Also, SacCalc may not be able to run HEC-1 if you specified input values that are beyond hydrologically reasonable limits, even if stock HEC-1 outside of SacCalc appears to give results. If after thorough investigation, you still suspect a program bug, please ​​send an e-mail message to the Development Review & Hydrology Section staff​, the owners of the program. Include an example ".scalc" file as an attachment.​