Water Act Article 5

The central authority-in-charge shall demarcate water districts according to the country’s natural pattern of waterways and submit the water district map to the Executive Yuan for approval and publication.
中文原文 水利法第5條
中央主管機關按全國水道之天然形勢,劃分水利區,報請行政院核定公告之。

English translation for reference only; the Chinese text prevails. Not legal advice.