|basin = retention|
|A retention basin catches stormwater and retains it, forming an artificial pond.|
|Rendering in openstreetmap-carto|
|Used on these elements|
|Status: de facto|
|Tools for this tag|
A retention basin is an artificial pond with vegetation around the perimeter, and includes a permanent pool of water in its design. It is used to manage stormwater runoff to prevent flooding and downstream erosion, and improve water quality in an adjacent river, stream, lake or bay.
The basin is normally filled with water.