近年來，台灣北海岸鄉鎮由於觀光遊憩活動多及交通方便之因素，旅遊人潮變多而造成環境污染程度升高；本研究之目的為以環境永續發展為前提，調查並監測八連溪及老梅溪之水質和水生昆蟲分佈情形，以了解北海岸區域的污染程度及現況，進一步期望能找出污染源，並加以處理或改善。本研究於92年8月至93年10月間，每月一次針對八連溪與老梅溪進行水質分析和水生昆蟲分佈調查。結果顯示八連溪與老梅溪水質穩定良好，平均水溫度約18~19℃，最高為31.8℃，最低13℃，常年溶氧均大於飽和溶氧量之70%，經水質指數(water quality index, WQI)分析評估為“優良水質”之河川。根據現場勘查，八連與老梅溪中之水棲昆蟲中以蜉蝣為最多，其次為蜻蜓、豆娘、水黽、石蠅、等共16科22屬，生物多樣性指數介於1.4~3.5之間，並且有由下游至上游漸增的趨勢。綜合生物指標法，八連及老梅溪為輕度污染之河川，主要污染河段以中下游為主。整體而言，八連溪和老梅溪水質穩定良好，但是進一步比較生物指數(Biotic Index，BI)與WQI值，有些採樣點兩種指數之間有差異，顯示可能有其他問題值得再多方面深入探討。
The environmental pollution of north coast of Taiwan has become noticeable recently due to the increasing visitors and activities brought by the ease of travel and increased ecological activities recently. The purpose of this study was to evaluate the water pollution of the north coast of Taiwan via investigating the water quality and aquatic insects profile of the regional rivers with environmental sustainable development as prerequisite. This study was conducted from Aug. 2003 to Oct. 2004 and the water quality was investigated monthly. Results showed that water quality of Ba-Lein and Lau-Mai rivers were good with temperature ranging from 13 to 31.8℃. The dissolved oxygen were at 70% saturation throughout the year. Among the water insect distribution, the most found species was zooplankton, and the dragonfly and damselfly were the next. There were 16 families and 22 geniuses of insects found in Ba-Lein and Lau-Mai rivers. The biodiversity index was ranked between 1.4 to 3.5 and increased from down stream to up stream. In conclusion, the water quality of Ba-Lein and Lau-Mai rivers were considered as good quality. There was slight discrepancy between the biotic index (BI) and water quality index (WQI) and might need further investigation.
