The Bridge - Coal Creek Trail

Coal Creek Trail

Take a moment to look at the creek actively flowing beneath the bridge. Throughout most of the year Coal Creek may seem like a mild force, slowly trickling through the canyon. How did the large boulders in the creek bed get there? Where does the water come from and where does it go?

However, during heavy rainstorms you can see large rocks, trees, and loads of sediment being transported downstream toward Cedar City. If you have never seen this in person, you need only look at the size of the giant boulders found in the stream-bed. Each of those large blocks were placed there by a quick and powerful flash flood. The effects of such a flood will likely have an impact on roads, houses, and other structures located downstream in Cedar City.

Coal Creek Trail flood boulders
Coal Creek contains many large boulders that were placed there (deposited) during a flood event. Imagine the amount of energy that this creek can contain to move such large and heavy material. Over the past few millions of years there have been many of these floods. Not only do these floods deposit coarse material, but they also act as very powerful eroders. Cedar Canyon has been carved by Coal Creek, mostly through the frequent flooding events that occur.
Coal Creek Trail artificial waterfall
The artificial waterfall to the east is designed to decrease the overall slope of the creek before the water reaches Cedar City. This can act to decrease the overall energy and devastation due to flooding. This structure also acts as a dam to divert water to irrigation canals in Cedar City.
Coal Creek Trail stream gauge
Just upstream from the bridge is the stream gauge. This gauge constantly measures the water discharge of Coal Creek. This tells us the volume of water flowing downstream in each second. This can help us to predict flooding events and also gives us a better understanding of the water budget in Cedar City. Stream gauge data can be found online. Photo by USGS.

Cedar City's Water Budget

All of the water you see in Coal Creek comes from the mountainous area to the east known as the Markagunt Plateau. This high elevation area collects deep snow each winter. This snow will slowly melt throughout the spring and summer and work its way into coal creek through a variety of tributaries and springs. By volume most of the water in coal creek comes from snowmelt. However, the flood events that transport large amounts of sediment and cause most of the erosion are typically the result of heavy rainfall.

Stream Sediment Load

Rivers and streams can move sediment in a variety of ways. Some materials are small enough to actually be lifted above the stream bed. Some of these materials are dissolved while others are actual rock grains that are suspended by the movement of water in the stream. The reddish-brown color that is often seen in Coal Creek is due to this suspended load. Larger materials are pushed along the stream bed. Grains can bounce along the bed through a process called saltation or roll along the bed through a process called traction.

Figure showing the different ways that sediment grains are transported in a stream system. Image from Pearson, 2005.

Educator Resources

Educators can download resources for teaching on the Coal Creek Trail. 

Download Educator Resources

Second grade student artwork
Student artwork showing the Coal Creek streambed with various boulders.

View more student artwork