impoundments

An impoundment is a body of water or other liquid that is confined or held back by a barrier such as a dam, levee, or containment wall, creating a reservoir for storage and management of the liquid. In water resources, impoundments are built to store freshwater, regulate flow, generate hydroelectric power, irrigate land, or provide flood control. They may also be used for recreation, wildlife habitat, or industrial purposes. The term can also apply to containment facilities for liquids other than water, such as tailings ponds in mining or other liquid waste impoundments.

Most commonly they are dammed reservoirs formed behind a dam on a river or stream. Off-stream impoundments store water in basins away from the main channel. Detention basins and retention ponds are designed to manage surface runoff. In mining and industry, tailings impoundments contain processed mine waste. Impoundments vary in size and in the materials used to construct the barrier, from concrete gravity dams to earth-fill embankments.

Typical components include the dam or barrier, a reservoir or storage space, spillway to pass excess water safely, intake structures, outlet works, and monitoring and control systems. Operating rules govern release of water, maintenance, sediment management, and safety.

Impoundments alter hydrology, sediment transport, and ecosystems; large-scale impoundments may displace communities and affect habitats. Safety concerns focus on dam integrity, flood risk, siltation, evaporation, and potential for dam failure; regular inspections and emergency action plans are required by regulations in many jurisdictions.

Regulatory frameworks and organizations monitor impoundment design, operation, and safety; data on capacity, storage, structural integrity, and hazard potential are maintained for planning and risk assessment.