An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Environmental Modeling Community of Practice

Green Tool


The Green Tool represents infiltration-based stormwater control practices. The tool was developed for HSPF users. From the tool graphic user interface, it allows modelers to select a BMP type, channel shape and BMP unit dimensions, outflow control devices, and infiltration method. Based on the user selection, the program generates an HSPF-formatted FTABLE. HSPF’s Reach module (RCHRES) represents infiltration BMPs whose specific characteristics are captured by the FTABLE. Infiltration BMPs are source control facilities that capture runoff from small impervious areas such as parking lots or roofs. When designing infiltration BMPs, we recommend the Maryland’s unified stormwater sizing criteria. The unified approach has five specific design objectives:  meet pollutant removal goals (WQv), maintain groundwater recharge (Rev), reduce channel erosion (CPv), prevent overbank flooding, and pass extreme floods. The tool can be used for a single BMP or a treatment train. Users must ensure that the two are linked through the SCHEMATICBLOCK of the User Control Input (UCI) file. Representing most infiltration BMPs in HSPF is straightforward; however, building an FTABLE for some BMPs, such as sand filters, may require several steps. The accuracy in representing a particular BMP depends on a user’s skill. The primary design considerations for any infiltration BMP are ensuring that it has the capacity to store the capture volume and that underlying soil can adequately drain the design’s capture volume within the permissible drainage time. This tool can be accessed at:  .

How to Run Green Tool

Run the GreenTool in your web browser.

The tutorial is available at .

Contact the Author

For questions and suggestions, please contact .


For citation, please use: Center for Exposure Assessment Models (2012). HSPF BMP Toolkit. National Exposure Research Laboratory. Athens, Georgia.