Seawater introduction to the reservoir of the Isahaya Bay Reclamation Project was carried out from April 24 to May 20, 2002. Seawater intake caused halocline and thermocline in the reservoir, and oxygen depression was temporarily observed in the vicinity of the drainage gates of the sea dike. Reductions in SS (suspended solids), COD (chemical oxygen demand), T-N (total nitrogen) and T-P (total phosphorus) in the reservoir, which were identified during the seawater intake, can be attributed to the dilution effect. In contrast, effluent loads into the coastal area outside the sea dike increased during seawater introduction periods due to the increase in drainage discharge from the reservoir.
