A Sajó vízminősége, hosszú távú védelme

Until the early 50’s, the Sajó was one of the richest rivers in fish in the country. From the 50’s on, a number of industrial plants were built in the valley of the river, and their waste water was directed into the Sajó without any or just with minor cleaning. As a consequence of these circumstances, the Sajó has become one of the most polluted rivers in Europe. On the occasion of a water quality measurement on the longitudinal section in 1974, the dissolved oxygen content of the water crossing the border was zero, the organic pollution characterized by oxygen consumption with dichromate (KOICr) was near the 300 mg/l value. According to the examinations in 2005, the water arriving the boundary section – except for the coliform number – is of bearable or better quality. Examinations based on the survey of the ecological state guided by the practise of EU Water Framework Directive exhibit improving water quality, as well. According to fish fauna surveys, 49 fish species have already returned to the Sajó, 15 of them are protected.