Urbanization of watersheds substantially changes the health of a stream by increasing rnimpervious surfaces that deliver pollutants directly to waterways. The major environmental rnproblem that Addis Ababa facing is the increasing impervious surface. Although improving rnthe riparian zone has been attempted to restore urban stream health in Addis Ababa, that rndoes not significantly improve it, since it is not equivalent to the scale of degradation of rnstreams based on recent studies. The main objective of the study is to introduce an rnappropriate type of watershed-level nature-based design measures for the rehabilitation of rnurban streams affected by the higher level of imperviousness in Addis Ababa. Stream rnrestoration can be achieved in this case by a cross-sectional study of the specific case rnwatershed to address the issue of urban streams and river system rehabilitation at the rnwatershed level by introducing appropriate nature-based design solutions and by rnupscaling the solution from the case site into the entire city river system. The study site is rnselected based on the density by comparing the built-up of upper catchments. The study rnestimates the existing level of effective impervious area for â€˜Kabaâ€™ river watershed and rnstream health improvement solution. The total impervious cover of the city and effective rnimpervious cover of the study area are 52 and 27.8 percent respectively. The current rncondition of the stream will not support its intended hydro-ecological functions. Differentrndesign scenarios are proposed in the watershed to reduce the effective impervious areasrnto a level at which measurable improvement in the ecological indicators. Finally, the studyrnconcludes that the proportion of the effective impervious areas is a good predictor of the rnecological condition of streams and it should be reduced to a level of recommended rnproportion to maintain stream health.