Stop Two - Middle Reaches

Moving farther downstream, you can see that many of the smaller headwater streams have come together, forming a wider, slower moving creek. Over time, the creek has cut into the banks, forming a more permanent streambed. Notice that the terrain here is less steep, so there are few, if any waterfalls.

Along both sides of the creek you will see flat areas of land where the creek occasionally overflows. This flat area is called the floodplain, and when the creek overflows it dumps sediments from the water onto the floodplain, returning some of the eroded soil from the headwaters area back onto the land. Periodic flooding is a natural process in the life of the creek.

There the creek runs deep and slow, it forms pools where fish often congregate. Between the pools are shallow stretches called riffles where the water runs fast and turbulent over a gravel bottom. Certain kinds of small fish and insects have become specially adapted to the swift currents and gravel bottoms of the riffles.

Human activities here in the middle reaches can have a major impact on the water and its inhabitants. For instance, if livestock have access to the stream, they may accelerate the natural erosion of the streambank, increasing the amount of sediments carried by the creek and changing the course of the stream.

In some areas, the stream channel has been straightened and widened, allowing the stream to flow unimpeded, thereby minimizing property damage from streambank erosion and flooding. But alteration of the natural flow of the creek can also result in the destruction of important habitat for many species of fish and other aquatic life and can increase the risk of flooding downstream.

Let's move on to the next stop!

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