Abstract
Although the north (main) basin of Lake Biwa has become progressively eutrophicated since the beginning of this century, its eutrophication was not so marked for the last 24 years from the standpoints of such physical and chemical parameters indicating trophic status as transparency, minimum dissolved oxygen concentration in the hypolimnion and total phosphorus concentration of the water body.
In spite of the above facts, the external phosphorus loading in Lake Biwa has been high enough to bring about its rapid eutrophication with reference to VOLLENWEIDER's (1976) prediction model. Mass balance of phosphorus for Lake Biwa was examined to explain the above discrepancy. As a result, it was suggested that phosphorus sedimentation plays a decisive role in the delay of the eutrophication of Lake Biwa (north basin).
