BT BM 108a(15) :לכריא דנהרא תחתאי מסייעי עילאי‏ : the lower ones [i.e. those who are downstream] help the upper ones in the dredging of the canal
See the entire entry for krāy, krāyā v.n. dredging

BT BM 108a(15) :לכריא דנהרא תחתאי מסייעי עילאי‏ : the lower ones [i.e. those who live downstream] help the upper ones in the digging of a canal
See the entire entry for syˁ vb. D to aid