Beresa reservoir has been exposed to industries and anthropogenic activities from local people in past years. In order to assess the water quality status of the reservoir, the macro invertebrate community (species composition) and their relative abundance was examined during the study period, between April and May 2016. Totally, 111 individual macroinvertebrate organisms were collected from the sites of the river. These organisms were from seven families, four orders, and one phylum Species belonging to different families were identified including Corixidae, Chironomidae (blood red) and Chironomidae (pale) were the most dominant in terms of species richness and abundance. Benthic macro invertebrate communities were less diverse compared to many Ethiopian rivers. The lower abundance and diversity of macro invertebrate could be due to poor ecological status of the river. The dominance of macroinvertebrate community indicated the lower water quality of the river. Such species dominate polluted water with poor oxygen concentration as they have some special adaptation mechanism that helps them to survive in such conditions. Samples with H-FBI values of 0-2 are considered clean, 2-4 slightly enriched, 4-7 enriched, and 7-10 polluted. Therefore, the HFBI value of River Beresa was 8.17 during the study time which lie in the range between 7 and 10. The most probable cause for the pollution of Beresa River could be wastes which are being released from Debre Berhan University and Debre Birhan Textile factory. In addition, other anthropogenic activities around the river could significantly pollute the river.