Lag time for a catchment is shown to be a variable which is strongly correlated with flood magnitude. Values for various parameters of rainfall and runoff were derived from the analysis of records for five small catchment areas. Lag time is defined as the time between the centers of mass of excess rainfall and direct runoff. Weighted mean discharge is used as the measure of average streamflow magnitude. No significant correlation is found between the lag and various characteristics of the areal and temporal distribution of rainfall. Therefore, the lag-weighted mean discharge equations best represent the variable lag time for the catchments studied.