3 Environmental Impacts of Hydroelectric Power

3 Environmental Impacts of Hydroelectric Power

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Hydropower refers to the electricity created by the motion of the water. Whether it’s rain, melted snow, streams and rivers from hills and mountains, it’s a precious resource of energy. If you’re ever been whitewater rafting, you know the amount of energy water can have. Naturally, humans tried to take advantage of this ever since ancient Greece, when they used water wheels. Nowadays, we are enjoying hydropower as much as we can. Today we are going to focus on a couple of environmental impacts of hydroelectric power.

Environmental Impacts of Hydroelectric Power You Didn’t Know About

We should start off by saying that there are three orders of environmental impacts of hydroelectric power. Mostly, this type of power is taken from dams placed on rivers and streams, making the dams the biggest factor in impacting the environment. In what follows, we will focus on how dams impact river ecosystems and offer more details about it.

1. First-Order Impacts

There are three types of first-order impacts triggered by the dams:

  • Water quality;
  • Hydrology;
  • Sediment load.

Naturally, all three of them are interconnected. But let’s start with the beginning. The water a dam stores in its reservoirs isn’t going to have the same quality as the one normally found in the river. Consequently, we will find higher levels of sediments and nutrients inside the reservoir.

This, in turn, can lead to the presence of extra algae, as well as other types of aquatic weeds. The danger here is the fact that the weeds can suffocate the animal and plant-life in the river. As such, people must control them and there are two ways of doing so: either by manual harvesting or by bringing some new fish species that can eat the plants. But more about the fish later.

Another issue here is the fact that there is a large amount of water that is lost. This takes place as the dammed reservoirs allow for a larger quantity of water to evaporate, in comparison to the regular levels of the flowing rivers. Not to mention that the flow regime is also strongly influenced by the appearance of a dam.

You might want to read: Hydropower Pros and Cons – How Efficient Is It, Really?

2. Second-Order Impacts

The second-order environmental impacts of hydroelectric power refer to primary production and morphology.

  • Primary production
    • Plankton;
    • Aquatic Macrophytes;
    • Algae;
  • Morphology
    • Channel Form;
    • Substrate Composition.

One of the most obvious changes that appear when building a dam is the modification of the channel. The latter will also trigger a fluctuation in the river flow as well, which means that even more things will be affected.

Just as we mentioned earlier, the difference between the water in the reservoir and the one in the river will affect the algae production. Furthermore, the plankton and aquatic macrophytes production are impacted as well. If there is too much water that gets stored in the reservoir, the river found downstream from it can dry out. To avoid this serious problem, most hydroelectric operators must release a certain amount of water a couple of times a year. There is also a strict procedure they need to follow, otherwise, they can influence the water levels downstream, thus harming the animal and plant life.

You might want to read: What Is Hydroelectric Energy and Why Do We Care About It?

3. Third-Order Impacts

Finally, the third-order impacts refer to:

  • Birds;
  • Mammals;
  • Fish;
  • Invertebrates.

We know that typically, a hydroelectric power plant is made up of a dam and a reservoir. Both structures have an influence on the fish in the river, for example. They can interfere with the natural fish migration process, thus affecting their populations. There are many species of fish (for example, salmon and shad) that use to swim up rivers/streams and reproduce in the beds of the waters.

Naturally, a dam built there will block the way. Luckily, there have been many approaches to solving this issue, such as using special fish ladders and elevators. These can help the fish move over the dams and reach the spawning ground. A good example is the Columbia River, where you can observe the fish ladders installed for the salmon. There are also some in-take screens that are used for this purpose. Moreover, fish and other organisms are often injured and even killed by the turbine blades, so experts try to design new types of blades.

Other Environmental Impacts of Hydroelectric Power

An important thing we should mention here is the fact that not all the wildlife impacts triggered by dams have a strict connection to hydroelectric power. Even so, such a facility can impact the aquatic ecosystems and not only. Let’s see some other effects of dams and hydroelectric facilities:

1. Global Warming Emissions

When people install or dismantle power plants, the process releases some global warming emissions. At the same time, some recent studies have shown that the operation of the facility also generates a significant amount of emissions. Obviously, they depend on the nature of the land and the size of the reservoir.

3. Covering Up Important Land

Naturally, when people build a new dam, this affects the land in the area as well, not only the water. The reservoir in the structure can cover up people’s homes, for example, and can extend to other important natural areas, archeological sites, or agricultural land. In many cases, building such a dam requires relocating people.

3. Greenhouse Gases

Yet another impact hydroelectric power has on the environment is the release of greenhouse gases. Inside the reservoirs, you can find gases such as methane or carbon dioxide, which reach the atmosphere. However, there are no studies to show the exact amounts of these gases that form inside the reservoirs. Luckily, scientists at the National Institute for Space Research in Brazil found a solution for this as well. They created a system that can capture the methane in the reservoir and burn it. Thus, they can further produce electricity.

You might want to read: Himalayan Glaciers at Risk Because of Climate Change


Finally, we can certainly say that there are more environmental impacts of hydroelectric power than you might have expected. From affecting the wildlife and the ecosystem in the rivers where people build them to releasing greenhouse effects and relocating people, there are a lot of consequences of building a hydroelectric power plant. Luckily, scientists are constantly working on ameliorating these effects and protect the environment.

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