In the Japanese occupation era, there was a 300-meter wide protective belt on both sides of the river in order to insulate the river against manmade pollution. Today, orchards and rows of vegetable plants are less than 10 meters from the stream's edge.
日據時代規定，國寶魚生活的溪流兩岸需要有三百公尺緩衝帶，就是要化解各種人為汙染，但今天果園、農田離溪邊卻不到十公尺。