In the Ethiopian highlands and Tana sub basin, there is a practical knowledge deficit in the development of stage discharge rating curves utilizing the salt dilution approach. The stage-discharge rating curve is the most commonly used for analyzing flow conditions, designing development works, and describing river channels. The aim of this research is to develop a stage-discharge rating curve and identify the geographic variance of runoff in three micro watersheds in the Tana Subbasin: Enkulal, Guale(2u), and Toma. To develop the stage discharge rating curve and to quantify the spatial variation of runoff, the rainfall, stage and discharge data were recoreded over a certain period. Discharge data were collected using salt dilution and floating methods while the stage data were recorded using staff gauge at each stream from June, 2019 to September, 2019. In each micro watershed, the stage and discharge relationship were created utilizing the power and polynomial equation with a very good determination coefficient (R2). The discharge obtained using the floating method did not differ statistically from that expected using the salt dilution method. At the outlet of Toma, Guale (2u), and Enkulal micro watersheds, the SCS equation produced a better correlation of measured and simulated runoff with coefficients of determination (R2) of 0.97, 0.94, and 0.98, respectively. The area that contributing runoff was range from 87% of the total area of the micro watershed during high rain fall periods and smaller than 51% the total area of the micro watershed in low rainfall periods.