What is an artificial obstruction built in a waterway called?

The term "barrage" refers specifically to an artificial obstruction built in a waterway, designed to regulate water flow and levels, often for purposes such as irrigation, flood control, or navigation. Barrages are typically constructed to support the diversion of water into canals or other water bodies, and they may allow for controlled releases of water downstream.

In contrast, dams, while also obstructions that affect waterways, generally serve to create a reservoir by impounding water rather than allowing it to flow through. Channels are engineered pathways that guide water but do not inherently act as obstructions. Levees are earth banks constructed alongside rivers to prevent overflow and manage floodwaters but do not typically involve a controlled barrier in a similar sense to a barrage. Thus, barrage is the most precise term for an obstruction that specifically regulates flow in waterways.