Deji Reservoir (formerly known as Dajian Reservoir) is located in the upper reaches of Dajia River, and boasts many of Taiwan's most impressive features, including not only the highest elevation dam in Taiwan, but also the first double-curved thin arch dam made of concrete in Taiwan, with a beautiful structure. The catchment area spans three cities and counties, namely Taichung City, Nantou County, and Yilan County.