The purposes of pond construction often dictate their landscape position. ‘In-line’ ponds are often built to intercept stream flow, for example as a source of hydropower. By contrast, ‘off-line’ ponds without influent streams may be suitable for a wide variety of other uses. Both in-line and off-line ponds typically have outfall structures (dams or standpipes) that convey water either continuously or periodically down- stream, although such structures are sometimes absent from smaller off-line ponds.