四分律刪繁補闕行事鈔 1.264

1.264

問：界中有水，得合結不？答：律中河者，除常有橋、船、梁，得結；若駛流者，不得。必有橋梁及淺水無難，準理應得。故《尼律》中云水者獨不能渡，此通界內外也。

Question: If there is water within the sīmā, may it be included and demarcated together? Answer: Regarding rivers in the Vinaya, except where there are permanent bridges, boats, or piers, it may be demarcated; if there is a swift current, it may not be. If there are bridges and piers, or shallow water without danger, in principle it should be permitted. Therefore, in the Bhikṣuṇī-vinaya it says that one cannot cross the water alone; this applies both inside and outside the sīmā.