You can download EFDC 126.96.36.199844 from our software library for free. EFDC lies within Education Tools, more precisely Science Tools. This free tool was originally produced by US Environmental Protection Agency.
From the developer:
The Environmental Fluid Dynamics Code ( EFDC ) is a multifunctional surface water modeling system, which includes hydrodynamic, sediment-contaminant, and eutrophication components.
You may want to check out more software, such as Trachtenberg Speed Math, SatCalc or MathMatic, which might be related to EFDC.