Biological Monitoring of Gharasou River by Using Macro Benthic Community Structure

Maintaining water resourcesquality,due to the recentdroughts andurban, ruraland industrialdevelopments isan important taskinenvironment. According to the importance and critical role of GharasouRiver inwatersupplyof Ardabil province which is located onNorth West of Iran, its quality evaluationseemsnecessary.In order to evaluate water quality of GharasouRiver for this purpose, samplingof benthoswas conductedinlowwaterandhigh waterseasons in 2012-2013 growing season. According to the results based on Hilsenhoffindex values, water qualities is average in first round and second round at all stations.The first and second stations were in the best situation. So, physico-chemical parameters including dissolved oxygen(DO), pH and BOD are seen the best in the first and second stations. The results showed that Hilsenhoff index was a good index to be used to indicate the state of the general water quality of the study river.