Determination of permitable distance between coldwater culture farms with common water supply in pirdanan river of West Azarbaijan

Regarding the increase in world population and decrease in fish stock, there is an urgent need to aquaculture practices. Coldwater fish culture is aiming at production and providing a part of protein needs of the country and a way reaching to self- sufficiency and preserve the water resources. Recently, multi- purpose use of water resources potential and especially the rivers of west Azarbaijan, for example, construction of fish farms at upstream of permanent rivers in order to make optimum use of the resources and the increase in employment has been considered . The waste water of these pools is usually discharged into the rivers. Regarding to increased production per unit area due to water resources and cold water fish culture restrictions to use regional facilities and fish farm construction, it is nessacery to determine limits between 2 farms. In this study with the goal of evaluation of the impacts of trout farm effluents on water quality parameters of Pirdanan River, the factors of water current, temperature, pH, EC, TDS, TSS, DO, BOD_5, NH_3, N-NO_2, N-NO_3, TP P-PO_4 according to standard methods were determined montly during 2014-2015 . Sampling sites were entrance, exit of Maroofi trout farm and the distances of 700, 1400, 2100 and 2800 m after the farm exit. Seasonal sampling of macro invertebrates from mentioned sites was conducted using stone leaching. The family and genus of macro invertebrates were identified using identification keys and abundance of macro invertebrate phylums for each site was determined. The results revealed that the values for water current, EC, TDS, TSS, N-NO_3 were significant. the values of water temperature, BOD5, TDS, TSS, N-NO^3- , N-NO^2-, NH_3, P-PO^4- , NH4+, N-NH3 were increased in site 2 compare to site 1 in all months and gradually in the river and its self- purification were decreased. In this study, 4 phylums, 4 classes, 7orders and 14 families of macroinvertbrates were identified from Pirdanan River. Ephemeroptera had the highest abundance in site 4; while Diptera had the highest abundance in site 2 (exit). Regarding that most of Diptera macro invertebrates were from Chironomidae, so it can be concluded that site 2 was the most pollutant site and sites 5 and 6 were more suitable condition. Therefore, considering the physic- chemical factors and macro inverteberates indices, 2100 m from entrance, (site 5) is recommended compliance with veterinary organization rules and other conditions of aquatic engineering, environmental and water operation standards