The impact of traditional coffee processing on river water quality in Ethiopia and the urgency of adopting sound environmental practices Abebe Beyene & Yared Kassahun & Taffere Addis & Fassil Assefa & Aklilu Amsalu & Worku Legesse & Helmut Kloos & Ludwig Triest Received: 21 June 2011 /Accepted: 24 November 2011 /Published online: 9 December 2011 # Springer Science+Business Media B.V. 2011 Abstract Although waste from coffee processing is a valuable resource to make biogas, compost, and nutrient-rich animal food, it is usually dumped into nearby water courses. We carried out water quality assessment at 44 sampling sites along 18 rivers that receive untreated waste from 23 coffee pulping and processing plants in Jimma Zone, Ethiopia. Twenty upstream sampling sites free from coffee waste impact served as control, and 24 downstream sampling sites affected by coffee waste were selected for comparison. Physicochemical and biological results revealed a sig- nificant river water quality deterioration as a result of disposing untreated coffee waste into running water courses. During coffee-processing (wet) season, the highest organic load (1,900 mg/l), measured as bio- chemical oxygen demand, depleted dissolved oxygen (DO) to a level less than 0.01 mg/l, and thus curtailed nitrification. During off season, oxygen started to re- cuperate and augmented nitrification. The shift from significantly elevated organic load and reduced DO in the wet season to increased nitrate in the off season was found to be the determining factor for the difference in macroinvertebrate community structure as verified by ordination analysis. Macroinvertebrate diversity was significantly reduced in impacted sites during the wet season contrary to the off season. However, there was a significant difference in the ratio of sensitive to pollution-tolerant taxa in the off season, which remained Environ Monit Assess (2012) 184:7053–7063 DOI 10.1007/s10661-011-2479-7 Abebe Beyene and Yared Kassahun are authors who contributed equally for this work. A. Beyene (*) : T. Addis : W. Legesse School of Environmental Health, Jimma University, P.O. Box 378, Jimma, Ethiopia e-mail: abebe.beyene@ju.edu.et A. Beyene e-mail: abebebh2003@yahoo.com A. Beyene : L. Triest Department of Biology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Y. Kassahun Jimma Agricultural Research Center, P.O. Box 192, Jimma, Ethiopia F. Assefa Department of Biology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia A. Amsalu Department of Geography and Environmental Studies, Addis Ababa University, P.O. Box, 150223 Addis Ababa, Ethiopia H. Kloos University of California, Box 0560, 185 Berry Street, San Francisco, CA 94143-0560, USA