QUAL2EU, Enhanced Stream Water Quality Model with Uncertainty Analysis, is a U.S. EPA steady-state model for conventional pollutants in branching streams and well mixed lakes. QUAL2EU can be operated as either a steady-state or dynamic model. It is intended for use as a water-quality planning tool. QUAL2EU can be used to study the impact of waste loads on instream water quality. It also can be used to identify the magnitude and quality characteristics of non-point waste loads as part of a field sampling program.
This model is public domain and can be downloaded for FREE using the link below.
For more advanced stream water quality modeling, please see:SMS - Surface-water Modeling System, 2D hydrodynamics and transportWMS - Watershed Modeling System, rainfall/runoff and 1D hydraulics