effect of isfahan city and its wastewater treatment plant effluent on some parameters of the water quality of zayandeh rood river

background: rivers and streams are important sources of surface waters. water quality of these resources depends on many factors including hydrologic, physicochemical and biological factors. these resources are important in terms of social, economic and political development.. zayanderood river is the only river in central basin of iran that has permanent fresh water. this river has an important role in providing drinking and agricultural water supply and , preserving industrial life in isfahan province. therefore, management and quality control of this water source is important. in this study the effect of isfahan city and its wastewater treatment plant effluent on some parameters of water quality of zayandeh rood river has been investigated. methods: samples for laboratory tests were taken from five stations along the river, from moosian to varzane. water quality parameters measured in this study include nitrate, phosphate, ammonia, bod 5 , cod and ph. at the time of sampling, the stage of water in moosian , choom bridge stations and varzane was also recorded.  it was found zayanderood water is affected from the city of isfahan even when there is no rain. findings: conclusion: however, the impact of isfahan wastewater treatment plant is much larger.