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Dam removal is a very important issue with worldwide implications. Most people are unaware of the negative effects that dams have on the ecosystem. There are some benefits that dams provide such as hydro-electric power, flood control, irrigation, and recreational purposes, but dams also have many costs as well. Dams can cause irreversible damage to an ecosystem and even force certain species into extinction. Dams cause unnatural levels of sedimentation in rivers and act as barriers for animal migration. However, the real question isn't should we remove dams to help restore the rivers to their natural states, but is it too late to remove the dams and restore the pre-dam conditions to the habitat?

There are many reasons for the removal of dams, but the main reason for removal is the negative impact dams have on an ecosystem. Dams cause the natural flow of a river to fluctuate and create sediment changes in the process. A reservoir forms above the dam and the ecosystem eventually drifts toward becoming lentic. Sediments build up in the area above the dam while the water below the dam becomes deprived of sediments due to the barrier the dam creates. The lack of sediments reduces the water quality of the water below the dam and the populations of organisms living in that water begin to struggle without nourishment or cover from predation. The dam also can cause the temperature of the water below it to fluctuate and usually makes the water much colder than the water above the dam. The unnatural flow caused by dams can confuse organisms that rely on seasonal changes to migrate. Dams also can make upstream migration impossible for many fish and can cause detrimental damage to salmon populations. The Columbia river lost approximately 50% of its suitable water for spawning because of dams, and as a result the salmon population dwindled from around 16 million fish to fewer than one million by 2008 and the fishing season had to be closed. Dams have caused many species to become endangered or extinct and have taken away the opportunities for anglers and other stockholders to appreciate the benefits these species provide.

On the other hand, removal of dams isn't necessarily beneficial in every instance. Some areas rely on the power generated from hydroelectric dams to function and need dams for irrigation. Ultimately, removing a dam does not guarantee that a river will return to its pre-dam conditions. In fact the drastic change to the ecosystem following the removal of a dam can be catastrophic. If the animals have adapted to living in a lentic environment over time, they will not be adapted to the lodic conditions that will instantly be restored to the ecosystem. The removal of dams is a very expensive and time consuming process, and the general public has a hard time understanding the reasons for removing them. Stakeholders such as anglers and boaters usually prefer having dams because the resulting reservoirs caused by the dams are much more suitable for recreational purposes than natural river would be. Homeowners with property on rivers are enraged by the removal of dams and the diminishing property values ensuing it. The entire process is controversial, difficult, and highly questionable, and the restoration process for the river is even more treacherous. The following video shows the lengthy process involved with removal and restoration of the Marmot dam in the Sandy River, OR.media type="youtube" key="CaNb2wouYUk" height="344" width="425"