A reach is a length of a stream or river, usually suggesting a level, uninterrupted stretch. The beginning and ending points may be selected for geographic, historical or other reasons – and may be based on landmarks such as gauging stations, river miles, natural features, and topography.
A reach may also be an expanse, or widening, of a stream or river channel. This commonly occurs after the river or stream is dammed. A reach is similar to an arm. The term "reach" can also refer to:
- An extended portion or stretch of land or water;
- a straight portion of a stream or river, as from one turn to another;
- a level stretch, as between locks in a canal;
- an arm of the sea extending up into the land.