Influences of urban wastewaters on the stream water quality: a case study from Gumushane Province, Turkey Adem Bayram & Hızır Önsoy & V. Numan Bulut & Görkem Akinci Received: 28 July 2011 / Accepted: 2 April 2012 / Published online: 22 April 2012 # Springer Science+Business Media B.V. 2012 Abstract Urban wastewater in Turkey is primarily dis- charged without treatment to marine environments, streams and rivers, and natural and artificial lakes. Since it has been well established that untreated effluent in multi-use waters can have acute and chronic impacts to both the environment and human health, it is important to evaluate the consequences of organic enrichment relative to the structure and function of aquatic environ- ment. We investigated the impacts of untreated munic- ipal wastewater discharge from the city of Gumushane in the Eastern Black Sea Region of Turkey on the surface water quality of the stream Harsit. Several key water-quality indicators were measured: chemical oxy- gen demand (COD), ammonium nitrogen (NH 4 + –N), nitrite nitrogen (NO 2 - –N), nitrate nitrogen (NO 3 - –N), total Kjeldahl nitrogen (TKN), total nitrogen (TN), or- thophosphate phosphorus (PO 4 3- –P), methylene blue active substances (MBAS), water temperature (t), pH, dissolved oxygen (DO), and electrical conductivity (EC). The monitoring and sampling studies were con- ducted every 15 days from March 2009 to February 2010 at three longitudinally distributed stations. While t, pH, DO, and EC demonstrated relatively little vari- ability over the course of the study, other parameters showed substantial temporal and spatial variations. The most dramatic differences were noted in COD, NH 4 + –N, NO 2 - –N, TKN, TN, PO 4 3— P, and MBAS immediately downstream of the wastewater discharge. Concentration increases of 309 and 418 % for COD, 5,635 and 2,162 % for NH 4 + –N, 2,225 and 674 % for NO 2 - –N, 283 and 478 % for TKN, 208 and 213 % for PO 4 3- –P, and 535 and 1,260 % for MBAS were observed in the summer and autumn, respectively. These changes were associated with greatly diminished seasonal stream flows. Based on NO 2 - –N, TKN, PO 4 3— P, and MBAS concentrations, it was concluded that Harsit stream wa- ter was correctly classified as polluted. The most telling parameter, however, was NH 4 + –N, which indicated highly polluted waters in both the summer and autumn. The elevated concentrations of both P and N in the downstream segment of the stream triggered aggressive growth of submerged algae. This eutrophication of river systems is highly representative of many urban corridors and is symptomatic of ongoing organic enrichment that must be addressed through improved water treatment facilities. Keywords Gumushane province . Harsit stream . Urban wastewater . Water quality Environ Monit Assess (2013) 185:1285–1303 DOI 10.1007/s10661-012-2632-y A. Bayram (*) : H. Önsoy Faculty of Engineering, Department of Civil Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey e-mail: adembayram@gmail.com V. N. Bulut Maçka Vocational School, Karadeniz Technical University, 61750 Maçka-Trabzon, Turkey G. Akinci Faculty of Engineering, Department of Environmental Engineering, Dokuz Eylül University, 35160 İzmir, Turkey