At the end of January, 2016, unusual odor originated from wastewater at a factory located in the upstream of the Agano River happened. The water quality item affected was odor, so water quality accident was rapidly detected by simple odor test at water purification plants. Additionally, the wastewater at the factory was identified as origin of the accident after upstream survey. Stuff of Niigata Water works cooperated with those of national and local governments and shared analytical results of high resolution mass spectrometry and candidates of causative chemicals, as a result, 2-methoxi-3,5-dimethilpirazine (MDMP) was identified as the causative chemical. After that, analytical methods of MDMP were improved and its survey in aquatic environment was conducted. From the experience of the accident, it was found that cooperation among waterutilities, institutes of national and local government is effective for collection of multifaceted and useful information because expertise and advanced analytical instruments are needed to identify unknown chemical.

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