HEC-EFMSim allows users to create and characterize ecological communities that are simulated in a data-defined virtual environment where they interact with that environment, themselves, and each other. It is a detailed simulation software. It is inherently spatial. It is primarily used to simulate population dynamics though its generic nature allows for inclusion of many ecological dynamics, including biogeochemical interactions.

The normal progression of tasks in HEC-EFMSim modeling is spatial setup, informatics, ecology, and simulation.

Simulation results can be viewed as animations of variables such as count, size, and density for virtual communities. Results can also be viewed as time series data via tabular formats.