A long-term research on reservoirs in the Jizera Mts (Czech Republic) and their tributaries was supplemented with a study of periphyton in main streams in 1996 and 2008, to document in a complex way the process of their recovery from anthropogenic acidification. The results show a reduction of man-made acidification, but a high natural acidity of waters in the upper plateau of the Jizera Mts, and reflect the differences between the streams (their character and water chemistry).