A stream pool, in hydrology, is a stretch of a river or stream in which the water depth is above average and the water velocity is quite below average.
A stream pool may be portion of the stream bed that is bedded with sediment or Armour with gravels, and in some cases the pool formations may have been formed as basins in exposed bedrock formations. Plunge pools, or plunge basins, are stream pools formed by the action of waterfalls.
A stream pools stretches of rivers, creeks, or streams that have an above average water depth and low velocity.
This pool portion of a stream often provides specialized aquatic ecosystem habitat for organisms that have difficulty feeding or navigating in swifter reaches of the stream, or in seasonally warmer water. Such pools can be important for juvenile fish habitat, especially where many stream reaches attain high summer temperatures and very low-flow dry season characteristics.