ENVIRONMENTAL CONCERNS SURROUNDING THE DEVELOPMENT OF Small-Scale HYDROPOWER
With a bitter taste in one's mouth from the construction of the Glen Canyon Dam, or many of the other mega dams, many environmentalists do not consider hydroelectricity power renewable. It is controversial because the construction damages the landscape, it alters the make-up of the precious water and it effects the surrounding habitat. Every single hydro site is different and there are countless regulations that assure that sites are complying with current environmental standards; however, there are people who value stream health as an equally important component to combating climate change as alternative energy. The Foundation for Water and Energy Education has determined four variables that contribute to how severe environmental damage caused by a hydro site can be-
“1) the size and flow rate of the river or tributary where the project is located
2) the climatic and habitat conditions that exist
3) the type, size, design, and operation of the project
4) whether cumulative impacts occur because the project is located upstream or downstream of other projects.”
Follow this link to see how a hydroelectric plant directly changes the surrounding ecosystem and river health:http://www.dameffects.org/index.html
Below is an expert from The Foundation for Water and Energy Education website that discusses all the possible environmental impacts from building a hydroelectric facility. At times, these concerns are specific to hydroelectric sites with a dam but provide a glimpse into how important stream and river health is to our environment as a whole.
Ecological Concerns
"Reservoirs and Stratification
Reservoirs, also called lakes, are created when storage projects are built. Reservoirs can significantly slow the rate at which the water is moving downstream. Surface temperatures tend to become warmer as the slower moving or “slack” water absorbs heat from the sun.
In addition to surface water warming, the colder water sinks toward the bottom because of its higher density. This causes a layering effect called stratification. The bottom layer is the coldest and the top layer the warmest.
When stratification occurs, there is also another ecosystem effect. Specifically, the colder water that sinks toward the bottom contains reduced oxygen levels. Further, at some sites when water is released from the colder, oxygen-depleted depths, downstream habitat conditions change because of the reduced oxygen level in the water.
Supersaturation
Supersaturation occurs when air becomes trapped in water spilled over a dam as it hits the pool below, creating turbulence. Because air is comprised of 78% nitrogen, the level of nitrogen dissolved in the water can increase dramatically. The affected water does not lose the excess nitrogen quickly. For fish and other species, supersaturated water can enter tissues. If fish swim from an area supersaturated with nitrogen to a lower pressure area, a condition similar to “the bends” in scuba diving can occur. This effect causes injury and can even cause death to fish.
Changing Water Levels
Building a storage project can raise the water level behind a dam from a few feet to several hundred feet. When stream banks and riparian areas become covered by the reservoir’s higher water level, the result is called inundation. Habitat conditions change and a new equilibrium emerges. As this occurs, a different set of dynamics begin impacting species that traditionally grow, nest, feed, or spawn in these areas.
Once built, storage projects can also raise and lower the level of water in a reservoir on a daily, weekly or seasonal basis to produce electricity. One term used to describe this process is “power peaking.” This occurs when, for instance, more water is released in the morning because electricity demands increase as people wake up and begin taking hot showers, using kitchen appliances, etc. In a riparian zone, (the area where moist soils and plants exist next to a body of water) this may result in shoreline vegetation not being effectively reestablished.
Sedimentation
Sediments, which are fine organic and inorganic materials that are typically suspended in the water, can collect behind a dam because the dam itself is a physical barrier. From the time a project is built, man-made and natural erosion of lands adjacent to a reservoir can lead to sediment build-up behind a dam. This build-up can vary based on the ability of a river to “flush”the sediments past the dam. It can also vary based on the natural conditions specific to the river and its upstream tributaries.
When sediments collect, the ecosystem can be affected in two ways. First, downstream habitat conditions can decline because these sediments no longer provide important organic and inorganic nutrients.
Second, where sediment builds up behind a dam, an effect called “nutrient loading”can cause the supply of oxygen to be depleted. This happens because more nutrients are now available, thus more organisms populate the area to consume the nutrients. As these organisms consume the nutrients, more oxygen is used, depleting the supply of oxygen in the reservoir.
Similarly, gravel can be trapped behind a dam in the same way as sediment. In cases where the movement of gravel downstream is part of establishing spawning areas for fish, important habitat conditions can be affected.
Erosion
Changing water levels and a lack of streamside vegetation can also lead to increased erosion. For example, the lack of vegetation along the shoreline means that a river or reservoir can start cutting deeply into its banks. This can result in further changes to a riparian zone and the species which it can support. Increases in erosion can also increase the amount of sedimentation behind a dam."
Habitat Concerns
"Fish
Based on their life cycle and migration and spawning patterns, fish can face a number of different and changing ecosystems. Listed below are the most common and serious fishery impacts that relate to hydroelectric projects.
"Wildlife
Riparian vegetation and its bordering waters provide critical habitat for birds, waterfowl, and small and large mammals. When a hydroelectric project results in inundation of a free-flowing river, the nesting, forage, and cover provided by these areas is temporarily or permanently lost.
When habitat is lost, animals are forced to move to higher ground or other areas where habitat conditions may be less suitable, predators are more abundant, or the territory is already occupied. As an example, ground birds like pheasant and grouse require cover and cannot successfully move to higher, more open, ground.
In cases where water levels stabilize at a new height, vegetation in riparian zones can re-emerge and species can re-populate an area. With storage projects, the riparian zone that re-emerges has conditions that now reflect that of a reservoir or lake rather than a free-flowing river. When such conditions occur, certain species will begin to decline, others will become more abundant, and some will populate these areas for the first time.
Ducks and geese are examples of waterfowl that are strongly attracted to the habitat conditions found in reservoirs. For some of these species, reservoirs are providing an important alternative to the wetland areas that they formerly occupied. Canada geese are one example of birds that now frequent reservoirs as part of their migration pattern."
*All the information above is courtesy of the Foundation for Water and Energy Education Website
"FWEE | Foundation for Water & Energy Education." FWEE. N.p., n.d. Web. 14 Apr. 2014. <http://fwee.org/>.
“1) the size and flow rate of the river or tributary where the project is located
2) the climatic and habitat conditions that exist
3) the type, size, design, and operation of the project
4) whether cumulative impacts occur because the project is located upstream or downstream of other projects.”
Follow this link to see how a hydroelectric plant directly changes the surrounding ecosystem and river health:http://www.dameffects.org/index.html
Below is an expert from The Foundation for Water and Energy Education website that discusses all the possible environmental impacts from building a hydroelectric facility. At times, these concerns are specific to hydroelectric sites with a dam but provide a glimpse into how important stream and river health is to our environment as a whole.
Ecological Concerns
"Reservoirs and Stratification
Reservoirs, also called lakes, are created when storage projects are built. Reservoirs can significantly slow the rate at which the water is moving downstream. Surface temperatures tend to become warmer as the slower moving or “slack” water absorbs heat from the sun.
In addition to surface water warming, the colder water sinks toward the bottom because of its higher density. This causes a layering effect called stratification. The bottom layer is the coldest and the top layer the warmest.
When stratification occurs, there is also another ecosystem effect. Specifically, the colder water that sinks toward the bottom contains reduced oxygen levels. Further, at some sites when water is released from the colder, oxygen-depleted depths, downstream habitat conditions change because of the reduced oxygen level in the water.
Supersaturation
Supersaturation occurs when air becomes trapped in water spilled over a dam as it hits the pool below, creating turbulence. Because air is comprised of 78% nitrogen, the level of nitrogen dissolved in the water can increase dramatically. The affected water does not lose the excess nitrogen quickly. For fish and other species, supersaturated water can enter tissues. If fish swim from an area supersaturated with nitrogen to a lower pressure area, a condition similar to “the bends” in scuba diving can occur. This effect causes injury and can even cause death to fish.
Changing Water Levels
Building a storage project can raise the water level behind a dam from a few feet to several hundred feet. When stream banks and riparian areas become covered by the reservoir’s higher water level, the result is called inundation. Habitat conditions change and a new equilibrium emerges. As this occurs, a different set of dynamics begin impacting species that traditionally grow, nest, feed, or spawn in these areas.
Once built, storage projects can also raise and lower the level of water in a reservoir on a daily, weekly or seasonal basis to produce electricity. One term used to describe this process is “power peaking.” This occurs when, for instance, more water is released in the morning because electricity demands increase as people wake up and begin taking hot showers, using kitchen appliances, etc. In a riparian zone, (the area where moist soils and plants exist next to a body of water) this may result in shoreline vegetation not being effectively reestablished.
Sedimentation
Sediments, which are fine organic and inorganic materials that are typically suspended in the water, can collect behind a dam because the dam itself is a physical barrier. From the time a project is built, man-made and natural erosion of lands adjacent to a reservoir can lead to sediment build-up behind a dam. This build-up can vary based on the ability of a river to “flush”the sediments past the dam. It can also vary based on the natural conditions specific to the river and its upstream tributaries.
When sediments collect, the ecosystem can be affected in two ways. First, downstream habitat conditions can decline because these sediments no longer provide important organic and inorganic nutrients.
Second, where sediment builds up behind a dam, an effect called “nutrient loading”can cause the supply of oxygen to be depleted. This happens because more nutrients are now available, thus more organisms populate the area to consume the nutrients. As these organisms consume the nutrients, more oxygen is used, depleting the supply of oxygen in the reservoir.
Similarly, gravel can be trapped behind a dam in the same way as sediment. In cases where the movement of gravel downstream is part of establishing spawning areas for fish, important habitat conditions can be affected.
Erosion
Changing water levels and a lack of streamside vegetation can also lead to increased erosion. For example, the lack of vegetation along the shoreline means that a river or reservoir can start cutting deeply into its banks. This can result in further changes to a riparian zone and the species which it can support. Increases in erosion can also increase the amount of sedimentation behind a dam."
Habitat Concerns
"Fish
Based on their life cycle and migration and spawning patterns, fish can face a number of different and changing ecosystems. Listed below are the most common and serious fishery impacts that relate to hydroelectric projects.
- Slower moving waters in a reservoir can strongly affect salmon for two reasons. First, they can become disoriented in slower moving waters; and second, the length of time it takes smolts to reach the ocean may increase. With disorientation and lengthened travel time comes an increased exposure to predators.
- Fish passing through or around a dam can become stressed, injured, disoriented, or die because of contact with turbines, the walls of the dam, or deflection screens. They then exit into a relatively small area where their exposure to predators is increased. While fish passage rates are often better than 90%, fish that must pass through multiple dams face proportionally greater risk.
- Supersaturation is a danger for fish going over a dam or through its spillway. If too much nitrogen is absorbed in the bloodstream, air bubbles form and create the equivalent of what divers call “the bends.” At high nitrogen levels, fish and some other aquatic species die. Also, if supersaturation conditions exist, fish passing through or around a dam will absorb greater nitrogen levels and suffer the effects as they continue downstream.
- When adult salmon and other fish migrate upstream, the dam can again present itself as a physical barrier. If a “fishway”does not exist, then passage to spawning grounds is lost. While fish ladders are the most common fishways, other examples include fish locks, fish elevators and transportation of fish upstream via truck. Where ladders are used as fishways, fish can find it difficult to find them if sufficient attraction flows are not provided at their base. Once up the ladder, they can again become disoriented and be sucked back over a dam or through its spillway. Salmon do not feed during their migratory journey back to their spawning grounds, so loss of energy and time become critical survival issues.
- Reservoirs can create changes in downstream habitat conditions. For instance, macroscopic plants in the Columbia’s estuary are an important food source for salmon migrating to the sea. These plants, however, are no longer as prevalent in the estuary as they once were. Part of this decline has been traced back to conditions caused by reservoirs in the mainstem of the Columbia and on the Snake river.
"Wildlife
Riparian vegetation and its bordering waters provide critical habitat for birds, waterfowl, and small and large mammals. When a hydroelectric project results in inundation of a free-flowing river, the nesting, forage, and cover provided by these areas is temporarily or permanently lost.
When habitat is lost, animals are forced to move to higher ground or other areas where habitat conditions may be less suitable, predators are more abundant, or the territory is already occupied. As an example, ground birds like pheasant and grouse require cover and cannot successfully move to higher, more open, ground.
In cases where water levels stabilize at a new height, vegetation in riparian zones can re-emerge and species can re-populate an area. With storage projects, the riparian zone that re-emerges has conditions that now reflect that of a reservoir or lake rather than a free-flowing river. When such conditions occur, certain species will begin to decline, others will become more abundant, and some will populate these areas for the first time.
Ducks and geese are examples of waterfowl that are strongly attracted to the habitat conditions found in reservoirs. For some of these species, reservoirs are providing an important alternative to the wetland areas that they formerly occupied. Canada geese are one example of birds that now frequent reservoirs as part of their migration pattern."
*All the information above is courtesy of the Foundation for Water and Energy Education Website
"FWEE | Foundation for Water & Energy Education." FWEE. N.p., n.d. Web. 14 Apr. 2014. <http://fwee.org/>.