Water Act Article 64

Flood shall be drained into the main channel or its distributary, or other rivers, lakes, or oceans. Special attention must be paid to the protection and maintenance of related structures and other important facilities. With approval of the superior authority, flood may be drained into other or newly constructed waterways.
中文原文 水利法第64條
宣洩洪潦,應洩入本水道或其減河、湖、海,並應特別注意有關建築物及其重要設備之維護。
但經上級主管機關之核准,得洩入其他或新闢水道者,不在此限。

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