Restoring Streams

Figure 1: On the left side is an unhealthy stream. On the right side is a healthy stream.

How is a Stream Restored?

Stream health is vital to a diverse and healthy environment. However, due to human influence, many streams have become unhealthy, leading to the loss of water quality, habitat, and wildlife. For this lesson you will learn signs of a healthy stream and ways to restore them.

Ways to restore a stream

When we restore nature, we want to work with nature. We are not opposing nature to fix it, we look at the natural processes and try to imitate them. There are two main ways we restore streams:

1. Piling up natural materials, like rocks, logs, and native plants along the edges of the stream
   1. Rock structures help slow down storm water flow (thus helping to prevent soil erosion).
   2. How this is constructed is dependent on the type of erosion and available materials.
   3. This link includes different methods of stream bank constructions that help slow down erosion.
2. Restoring natural plant life
   1. This includes planting a diversity of native plants near the stream.
   2. A variety of structural plants (tall, medium, and short).
   3. Planting native plants helps restore the stream by bringing structural plant diversity, a canopy, plant diversity, and a vegetation buffer to a stream.
3. Induced Meandering
   1. You may have noticed that rivers aren’t straight, they usually curve and bend. Check out this video to find out why that happens.
   2. We want to replicate this movement of rivers because a river that curves is a lot healthier than a river that just flows straight. This is because the curves of the river help retain sediment, lessen erosion, and offer habitats for plants and wildlife.

Figure 2. Meandering river on left side and a straight river on the right. Notice the differences in health?

Signs of a Healthy Stream

1. Structural Vegetation Diversity: More than three height classes in vegetation. This means that there is tall vegetation (like trees), medium vegetation (like shrubs), and short vegetation (like grass).
2. Lower Bank Stability: The stream’s bank is stable and experiencing little to no erosion.
3. Plant Diversity: A variety of plants is often a sign of a healthy stream.
4. Canopy shading the water: This helps cool the stream. Cooler water means more oxygen, and more and happier aquatic life.
5. Water Quality: Testing for turbidity (how cloudy the water is with particles), pH, and nutrients (Nitrogen and Phosphorous) help determine stream health.
6. Pools and Riffles: Pools are deeper sections of the stream  that provide still water while riffles are shallow parts with turbulent water. A stream needs a good mix of both, as pools provide aquatic life habitat. Riffles are also important as they make the water move fast, thus providing more oxygen to aquatic life.
7. Vegetation Buffer: The dense vegetation alongside the river helps trap sediment and slow runoff. This is important as it prevents erosion in the stream.

An unhealthy stream would not meet the qualifications above!  For example, a stream with a lot of erosion is unhealthy. Keeping in mind what a sign of a healthy stream is, we can develop ways to restore streams back to health.