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Raising Kinmen’s Reservoir Water Quality to Share Purified Aquatic Environment with Eurasian Otters

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To improve the water quality of lakes and reservoirs in Kinmen County, reduce nutrient pollution and raise the efficiency of purification of water resources, since February 2022 the EPA has been cooperating with Kinmen County, National Cheng Kung University and National Taiwan University of Science and Technology to set up the Kinmen County Multi-soil-layering Pilot Test Site next to Xiaotaihu Lake. Since the start of the site’s operation in July 2022, water purification has been effective, thereby contributing to the sustainable development of Kinmen’s tourism.

Kinmen County’s tourism has developed rapidly and the number of homestays and tourist visits has grown significantly in recent years, making proper treatment of sanitary wastewater a must. Nutrients such as nitrogen and phosphorus were the culprits that caused eutrophication of reservoirs and water quality deterioration in the past. In recent years, the EPA has been cooperating with the Kinmen County Government to gradually build up wastewater intercepting projects and implement pollution control measures. As a result, the amount of household, military camp and livestock wastewater -- the origins of point-source pollution loads of nitrogen and phosphorus -- discharged into Shanwai River have been greatly reduced.    

Since currently 60% to 70% of the pollution loads of Shanwai River and Taihu Reservoir come from non-point source pollution, innovative methods need to be introduced to further improve the water quality of Taihu Reservoir. Examples include developing and introducing clean water sources upstream from the reservoir, and using the multi-soil-layering (MSL) method to circulate and purify the reservoir water.   

The pilot test site uses advanced technologies introduced from abroad. Through layered filter bags that are filled with mixed materials (including sand, iron particles, activated carbon particles, rice straw and other media) and permeable layers of gravel, ten metric tons of lake water can be treated per day. The pilot test system was completed by the end of July 2022, which has effectively improved the water quality of the reservoir. Suspended solids (SS) and total phosphorus have fallen to under 5 mg/L and under 0.05 mg/L, respectively. The system not only prevents wastewater from affecting Kinmen’s precious water resources, but also protects the habitat that Eurasian otters rely on.  

Executive Director of the Kinmen Wildlife Rehabilitation and Conservation Association Yuan Shou-Li said that with assistance from the Kinmen County Government and the Society for Wildlife and Nature, efforts to conserve Eurasian otters around Taihu are gradually getting results. Reducing pollution in the Shanwai River has not only ameliorated the reservoir eutrophication problem, but has also helped to conserve Eurasian otter habitat.

The EPA will continue to promote strategies to improve lake and reservoir water quality in Kinmen County. In addition to improving the quality of the water supply, the EPA will commit itself to protecting aquatic habitats and build a quality living environment. It looks forward to realizing the vision of raising Taihu’s water quality while building a friendly relationship between Eurasian otters and human living environments, so as to enable Eurasian otters to continue living with ease in the purified aquatic environments of Kinmen.  

Excerpt from Major Environmental Policies, October 2022

Ministry of Environment