Stream+Order

Stream Order



When two first order streams combine they make a second order stream. When two second order streams combine they make a third order stream and so on. However, if two streams of different orders combine the stream of the lower order simply flows into the other stream. For example, if a second order stream flows into a third order stream, the stream remains a third order stream and the order stays the same. The largest order is the twelfth order and it is held only by the Amazon River.

The differences in stream size affect the wildlife that are able to live there. For example, a first order stream is very small and so it can only hold very small fish if any and mainly consists of insects. But as the streams combine and grow, they can start to hold larger and more fish and other freshwater creatures, along with plants.

Humans have impacted streams and rivers by building dams and pumping water from them. Building a dam stops the way that stream order works because it just creates a lake and the stream cannot combine with others of its order and continue to grow. If humans pump water from a stream, then it effects the size of the stream making it smaller. If that stream combines with another, then the stream that comes from these two will be smaller than it would have been if humans would have left it alone. When the stream is smaller it can't hold as much wildlife so they will have to compete with other organisms for the space.

First-Order Second-Order Third- and Fourth-Order [|Stream order Info.]