Interviewing questionnaires to riverside residents of Mishima, governments officials and a designer of the riverscape have made clear that various projects proposed have been carried out for improvement of the river environment since 1990. These projects have produced not only favorable effects but also unfavorable ones. One of the unfavorable results is that residents' periodical river cleanings sometimes have taken away all aqua plants which are essential for aqua animals. Studies on aqua plants and animals including ecologists of different fields seem to be necessary for solution of this problem. This was one of the 5 results obtained in this study on the projects' unfavorable effects and the solutions.
