Granular filters are used in embankment dams to prevent impermeable materials fromrninternal erosion, while draining seepage water to prevent saturation of the downstreamrnembankment. Such materials are usually assessed from courses of rivers or streams thatrncontain alluvial sand and gravel materials and their suitability or performance has beenrnevaluated using existing filter design criteria based on particle size ratios. During this workrnsame assessment of a granular material which derived from weathering of the LowerrnSandstone unit of the Mesozoic Rock Formation of Ethiopia in protecting red tropical clayeyrnsilt soil has been done. Its overall characteristics, especially those relevant to filter design,rnhave been studied. It is also compared with respect to an alluvial source, found at relativelyrndistant place from research site. The geometrical criteria have been mainly checked using thernformulas and recommendations proposed by many scholars and standards. In addition to this,rnthe final gradation or grain size distribution of a suitable filter material has been preparedrnbased on the gradation of the base material following the design procedures prepared byrnUnited States Soil Conservation Service (USSCS).rnThe residual granular material, which was sampled and analyzed for grain size distribution,rnnearly satisfies most of the filter criteria, but it is a little bit finer. Of the various criteriarnavailable, the USSCS method and Sherard recommendations have been given more emphasisrnas they consider the type of base material and accordingly proposed different approaches andrnratios for design of the filter. The gradation curve for the average residual filter (averagingrnthree samples from different localities) prepared and also checked with the empirical criteriarnand design rules together with one alluvial soil from the distant source. The assessment resultrn(especially USSCS method) indicates that the residual material almost satisfies therngeometrical criteria, except it becomes a little bit finer. Whereas, the average residual soil andrnthe alluvial sediment satisfies completely both requirements of filtration and draining. As tornthe other characteristics of the filter, all materials (residual and alluvial) have satisfactoryrnquality; the grains of the residual sand are dominated with quartz, while the alluvial isrnfragments of basaltic rocks.rnThe behaviour of the base soil, which is related to its dispersive nature, also examined in arnlaboratory test. The result indicates that the base soil can be categorized as non-dispersive