Abstract
<title>Abstract</title> <p>Wetland water quality models are central to evaluating phosphorus (P) removal and restoration planning in managed landscapes such as the Florida Everglades. The Dynamic Model for Stormwater Treatment Areas (DMSTA), a legacy spreadsheet/VBA implementation limits transparency, reproducibility, and integration with other workflows. We developed DMSTAr, an open-source R implementation that preserves DMSTA equations, numerical procedures, routing logic, and version-specific behavior within a modular, testable framework. We verified DMSTAr against legacy outputs using identical inputs, parameters, initial conditions, and network structures from four major Everglades planning applications. Agreement was evaluated using bias, median absolute difference, root-mean-square error, symmetric percent difference, and graphical diagnostics. DMSTAr reproduced legacy behavior with negligible systematic bias and high agreement across applications. DMSTA and DMSTAr also exhibited nearly identical sensitivity to integration step size. DMSTAr therefore provides a faithful, reproducible, extensible, accessible and adaptable implementation of DMSTA for scenario analysis, diagnostic evaluation, and long-term wetland water-quality modeling.</p>