Study of Coliform Contamination of Karganrood River in the West of Guilan Province

Water pollution is a major global problem which requires continuous assessment and revision in water resources policy at all levels. Karganrood river is one of the most important river in Guilan province and on its way crossing agricultural areas in Talesh country and villages collect the pollutants. One of the main sources of rivers and lakes pollution is intering urban and industrial wastes into rivers that due to the entry of these materials, the structure of the rivers is transformed; because it is disrupting the natural flow of fish migration and so preventing the formation of floods and appropriate conditions for fish spawning. Study of microbial contamination was performed over a one year period and sampling was performed seasonally and once every season. The contamination rate was studied by counting total coliforms (MPN) method. The stations studied were selected from the upstream, middle and estuary regions and sampling was carried out from the surface and sediment of the river. Most of the total and fecal coliform contamination were related to bed and estuary regions which reducing water flow, passing through urban and agricultural centers and entering the centers' wastes into the river and settling in the river bed and estuary have led to increase the amount of contaminations. Totally, the contaminations average (surface and sediment) include: the highest amount of coliform contamination was 44.3 numbers in 100 cubic centimeters and the highest amount of fecal coliform contamination was 26.9 numbers in 100 cubic centimeters in summer season. It should be noted that, all the results of studied physical and chemical factors were in the standard range of discharge to the surface water and the bacterias' growth were increased due to increase of the weather temperature; so, decresing water volume in summer season causes increase of the bacterias percent in water