Reference for Bava Batra 198:9
דרך היחיד ד' אמות דרך הרבים שש עשרה אמה דרך המלך אין לה שיעור דרך הקבר אין לה שיעור המעמד דייני צפורי אמרו בית ארבעה קבין:
whose banks have been worn away, may be repaired [with the earth] of that field [through which it runs], for it is known that the banks could not have been washed away except into that very field.<span class="x" onmousemove="('comment',' Hence, the earth for reconstruction also may be taken from that field. ');"><sup>15</sup></span> R. Papa demurred: Let the field owner say, [to the owner of the canal]. 'Your water has lowered your ground'!<span class="x" onmousemove="('comment',' The water may have carried away the earth of the banks else where. Why should the field owner be expected to supply earth for repair from his field? ');"><sup>16</sup></span>