Initial conditions provide the water quality (WQ) constituent initial concentrations at the start of the simulation. HEC-ResSim provides an editor for creating and defining initial condition set(s). Initial condition set(s) are linked to a Geometry dataset (Chapter 4) and a WQ Constituent Set (Chapter 5). When an initial conditions set is created, the identified geometry and water quality constituent set provides the inflow locations (reservoirs, junctions, and reservoir outflow junctions) and WQ constituents for the user to define. The user must then specify the reservoir elevations and WQ constituent initial values for each WQ constituent at each inflow location. Reservoir elevation values must be entered as monotonically decreasing to provide a stratified elevation view of the constituent initial values. The prerequisites for completing the Initial Condition Set is a Geometry dataset (Chapter 4) and at least one WQ Constituent Set (Chapter 5). The Initial Condition Set is not used in any WQ Dataset.