What Is a Dam Across a River Called?

A structure built across a river to impound water is simply called a dam (or river dam). Dams serve multiple purposes:

• Flood control – regulate peak flows
• Hydropower – generate electricity via turbines
• Water supply – irrigation, municipal, industrial
• Recreation – reservoirs for boating, fishing
• Navigation – maintain channel depths

Dams vary by material (concrete gravity, arch, embankment/earthfill, rockfill), size (small weirs to mega-dams like Three Gorges), and design life (50–100+ years). Key components include spillways, outlets, intake structures, and monitoring instrumentation. Environmental impacts—sediment trapping, fish passage blockage, methane emissions—are now central to dam planning and removal decisions.