Spillway

n.

1.

A sluiceway or passage for superfluous water in a reservoir, to prevent too great pressure on the dam.

Noun

1.

spillway - a channel that carries excess water over or around a dam or other obstruction Synonyms: wasteweir, spill

aqueduct, arroyo, bed, canal, creek bed, culvert, donga, dry bed, flume, gulch, gully, gullyhole, headrace, irrigation ditch, nullah, race, river bed, riverway, runnel, sluice, spillbox, stream bed, streamway, swash, swash channel, tailrace, wadi, water carrier, water channel, water furrow, water gap, water gate, watercourse, waterway, waterworks