Abstract
Artificial lagoon that aims restoration of littoral zone in lake and non-point pollutants control was constructed in 1998 at the river mouth of Kawajiri River which flows into Lake Kasumigaura in Japan. This artificial lagoon has an area of ca. 30, 000m2 and a depth of 1.0m. The function of artificial lagoon for pollutant control was surveyed in 1999 and 2000. Water quality in artificial lagoon is mid-range between river and lake under normal weather condition. Artificial lagoon cuts 10-50% of SS, 20-50% of T-N, and 30-99% of T-P of runoff of rainwater. Annual removal ration of artificial lagoon was estimated between December '98 and November '99. Removal ratio was calculated as the ratio between sedimentation weight in artificial lagoon and annual load of Kawajiri river. 191% of SS, 19% of T-N, and 83% of T-P was removed by artificial lagoon. This SS probably includes not only river load but also lake load.
