In Florida, we often have to calculate the annual nutrient loading resulting from stormwater, especially when comparing and permitting development projects. There are a few key, approved tools that are used for this work:
- Hand calculations, using approaches prescribed in the Florida Department of Environmental Protection (FDEP) Applicant’s Handbook Volume 1
- BMPTRAINS, a free water quality tool created by the University of Central Florida, that has been removed from download as of 2025. This was removed due to “the need for updated software to address new stormwater regulations.” (https://stars.library.ucf.edu/bmptrains/26/). As far as we know, use of this tool is no longer approved or endorsed by UCF.
- BMPFAST, a water quality tool created by UCF, which now charges $500 per license. This tool released in April, 2026, and is the direct successor of BMPTRAINS.
The calculation methods in the FDEP Applicant’s Handbook Volume 1 are not complicated in nature. And now, all options that are not on the back of a napkin cost money.
For these reasons, DRUID has developed its own computational engine. Meet the SAGE tool, “Stormwater Analysis and GSI Evaluator.” (GSI = Green Stormwater Infrastructure).
This tool is totally free, open source (Apache-2.0 license), and know that we at DRUID do not make a single penny from this project, or this site.
It is designed to match the calculations and tables directly from the FDEP AH Volume 1, Appendices M through O, not BMPTRAINS/BMPFAST results.
https://github.com/Druid-Sage/SAGE
Download the folders on the above github link, peruse the README for instructions, and give it a try.
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