AQUATOX
EPA's aquatic ecosystem model — fate and ecological effects of nutrients, toxics and stressors together.
The standard 2D reservoir and stratified-river water-quality model — temperature, DO and eutrophication.
by Portland State University
CE-QUAL-W2 simulates hydrodynamics and water quality in water bodies that stratify: longitudinal-vertical (laterally averaged) 2D transport with a full eutrophication kinetics library — temperature, dissolved oxygen, nutrients, multiple algae and zooplankton groups, pH, sediment diagenesis. Reservoir management questions (withdrawal levels, TDG, bloom risk) are its home ground.
Maintained for decades at Portland State University with US Army Corps roots, it is free, source-available and deeply validated — the default choice worldwide for reservoir water-quality studies where 3D CFD would be overkill.
Other water quality & environmental tools covering similar workflow stages.
EPA's aquatic ecosystem model — fate and ecological effects of nutrients, toxics and stressors together.
EPA's watershed assessment suite — HSPF continuous watershed-quality modelling with GIS and data access built in.
Open-source 3D hydrodynamics and water quality — the EFDC lineage modernised, with a commercial GUI option.
USGS R package for long-term water-quality and streamflow trends — home of the WRTDS method.
The classic river water-quality model — DO, nutrients and algae along a 1D stream network.
EPA's Water Quality Analysis Simulation Program — eutrophication, toxics and sediment in rivers and estuaries.