Rapid industrialization in East Asia is causing adverse effects due to atmospheric deposition in terrestrial and freshwater ecosystems. Decreasing stream pH and alkalinity and increasing NO 3 -concentrations were observed throughout the 1990s in the forested Lake Ijira catchment in central Japan. We investigated these changes using data on atmospheric deposition, soil chemistry, stream water chemistry, and forest growth. Average atmospheric depositions (wet ? dry) of 0.83, 0.57, and 1.37 kmol ha -1 year -1 for hydrogen, sulfur, and nitrogen, respectively, were among the highest levels in Japan. Atmospheric deposition generally decreased before 1994 and increased thereafter. The catchment was acidsensitive; stream alkalinity was low (134 lmol c l -1 ) and pH in surface mineral soils decreased from 4.5 in 1990 to 3.9 in 2003. Stream NO 3 -concentration nearly doubled (from 22 to 42 lmol c l -1 ) from the late 1980s to the early 2000s. Stream NO 3 -concentration was