perennial stream

A stream or reach of a stream that flows year-round in a well-defined channel is known as a perennial stream, also called a permanent spring. The Army Corps of Engineers defines a perennial stream as one that flows 365 days in a typical year. The stream flows when it receives significant amounts of water during wet periods; when it receives groundwater discharge from below, reaching the surface through springs or seeps; or when it receives long-term water from melting snow and ice. Perennial streams can dry up, though, particularly during extended periods of drought, damaging the life within them that depends on constant flow. The distinction between perennial and intermittent streams is often a subject of controversy in localities, as specific conservation ordinances often set exact guidelines for a property with a designated perennial stream.

Jeffery Renard Allen