A scheme for determining the optimum length of streamflow record and the optimum frequency of discharge measurement has been applied to the gaging station on Arroyo Seco, an intermittent stream near Soledad, California. If the streamflow record is used only in the design of a water supply reservoir at the gage site, the optimum record length is found to vary between 9 and 56 years, depending on nonhydrologic time constraints. The optimum frequency of measurement of discharge for calibration of the station rating curve is found to be indeterminate. Sensitivity analysis indicates that the optimum length of record is more sensitive to the variability of the streamflow and the planned level of development at the site than to discount rate or cost of obtaining streamflow data.