HEC-ResSim Water Quality User's Manual - Working Draft for Review 7. Observed Water Quality Dataset Define Observed Data Current: Constant Value PDF Download PDF Download page Constant Value. Current page All pages Constant Value To define a constituent using the Constant Value data source option:From the editable data panel, open the Data Source dropdown list and select Constant Value (as shown in the Observed Dataset Editor – Constant Value Data Source).The editable panel below the Data Source dropdown will update for the selected constituent.Enter the desired value for the constituent in the Constant Value box (e.g., 9.2).Optionally, enter a description for the constituent in the Description box (this is recommended for clarity).Once these steps are complete, the selected constituent will be defined with a constant value.Observed Dataset Editor – Constant Value Data SourceClick Apply to save the entered value before navigating to a different data source, constituent, observed station, or observed dataset.Click OK to save the entered data and close the Observed Dataset Editor. ×