SAPROBIOLOGICAL STATE OF THE RIVER VARDAR–UPPER PART/1987–1990 (REPUBLIC OF MACEDONIA)

The investigation was focused on the water quality in a 60–kilometer long area in the upper part of the River Vardar (the Polog Valley geographical unit). Sixty samples of bio–indicators were seasonably collected from five profiles in the period from 1987 until 1990. It was concluded that the water quality decreases from the spring, which is a xenosaprobic zone to the α–mesosaprobic one when leaving the valley, and the β–mesosaprobic zone is mostly present. The anthropogenic factor has caused large changes in the natural rhythm of water quantity, as well as to the riverbed essence. The same factor has caused severe communal, industrial and agrochemical pollution. These circumstances have caused deterioration of the water quality. In spite of this, the River Vardar in this part of the cross has an enormous power for self–purification, and therefore it still represents a salmonid ecosystem.