One way of categorizing streams is by
stream order. Most streams begin as
springs or boggy seeps of groundwater. Some
flow from lakes without an inlet. These
fledgling streams are labeled first
order. When a first order stream meets
another first order stream, the resulting flow
is a second order stream.
The second order stream picks up additional
first order streams, but remains second order.
Only when two second order streams meet is the
result a third order stream.
As you might expect, there are vastly more
small streams than large ones. In fact, there
are about four (4.4) times as many streams of
one order than of the next higher order. First
order through third order streams make up about
85 percent of total stream miles in the United
2000) and (Leopold
et al., 1964).