Examined Plan of off-flavor of Tap Water by Nutrient Managements in the Upper of the Kinokawa River

Abstract

The off-flavor taste of tap water due to 2-methylisoborneol (2-MIB) derived from blue algae is one of the water quality problems associated with high nutrient loads in the Kinokawa River. Existing monitoring data showed that 2-MIB concentrations tended to increase when total phosphorus (TP) concentrations exceeded 0.02 mg/L. This study employed mass load and river water quality analyses to examine ways in which TP loads in river runoff could be mitigated. The results suggested that TP mass loads could be reduced by approximately half if the drainage volume standards defined in the Water Pollution Control Law were more stringent. In addition, halving current mass loads could reduce TP concentrations to less than 0.015 mg/L and limit any increases in the concentration of 2- MIB.