What is the lowest elevation to which a stream can downcut?

The lowest elevation to which a stream can downcut is known as the base level, which is typically defined by the level of the body of water into which the stream flows, such as a lake or the ocean. If the stream enters a lake, the lake level serves as the base level, while for rivers flowing into the ocean, sea level acts as the base level. Streams can downcut to this level but cannot erode below it. Changes in base level, such as tectonic uplift or sea level fluctuations, can affect a stream's erosion potential.