Effects of Dams on Pacific Salmon Migration in the US essay

8. Historical Migration of Pacific Salmon and numbers on the pacific coast lower 48.

Historically, the migration of Pacific salmon on the pacific coast of the US lower 48 was vitally important for the survival of the salmon population because Pacific salmon migrated to the coastal rivers for reproductive purposes. It is the coastal rivers, where Pacific salmon youth grows and moves back to the ocean. In such a way, the lifecycle repeats over and over again as Pacific salmon migrates from the ocean to the coastal rivers for reproduction and growth of youth and then moves back to the ocean. This migration persisted historically throughout millions of years. In the course of evolution, Pacific salmon is accustomed to move to the coastal rivers lower 48. At this point, it is important to place emphasis on the fact that, if Pacific salmon gets limited access to the coastal rivers lower 48, the survival of salmon population will be under a question because the youth can hardly survive in other regions, especially in the ocean. In fact, such a change would be disastrous for the population of Pacific salmon to the extent that Pacific salmon can become absolutely extinct. In such a situation, the drop of the population of Pacific salmon is, to a significant extent, is the result of the deterioration of the environmental conditions and the limitation of the access of Pacific salmon to the coastal rivers lower 48.

8. The dam craze over water storage that hurt the salmon on the pacific coast lower 48.

In this respect, dams constructed on the coastal rivers lower 48 has had a particularly negative impact on the population of Pacific salmon. At any rate, many specialists (Barker, 2007) argue that the construction of dams provoked the consistent deterioration of the population of Pacific salmon as well as some other species. To put it more precisely, Pacific salmon faces the problem of the consistently limited access to the coastal rivers that prevented them from the successful reproduction. As a result, dams may be one of the major causes of the consistent drop of the population of Pacific salmon because salmon cannot access the destination, where the reproduction can occur successfully. In addition, dams change the flow of rivers that also affects the migration of Pacific salmon because salmon cannot use the traditional ways of the migration and many salmons just die on their way throughout coastal rivers.

In such a context, the role of damns and their affect on the migration of Pacific salmon can hardly be underestimated, although the true impact of dams on the migration Pacific salmon needs further studies, but it is already clear that dams comprise a part of human activities that have influenced the environment consistently and affected the population of Pacific salmon.

2. Columbia and Snake River Salmon Stocks
3. Decline in salmon numbers over the past century.

In the course of the 20^th century, the population of Pacific salmon has dropped consistently under the impact of human activities. In this regard, the construction of dams has had a particularly dangerous impact on the population of Pacific salmon. At this point, it is worth mentioning the fact that Such changes provoked by the dams also alter the timing and magnitude of water releases and downstream river flow, changing behavioral cues to salmon (Chilcote, 2009). Obviously, the change of the flow, temperature, and other effects of dams’ construction provoked consistent changes in the population of Pacific salmon. For instance, changes in flow can interfere with the timing and homing ability of upstream spawning migrations, scour out fragile eggs in salmon nests, and influence the success of seaward smolt migrations (Chilcote, 2009). As a result, just under 2% of salmon retrace the improbable journey of their forebears; 13 Columbia salmon stocks are listed as threatened or endangered (Gross, 2008).

In such a situation, it is quite natural that the population of Pacific salmon has dropped consistently in the course of the last century, while today Pacific salmon becomes extinct. There are an estimated 74,993 dams in America, blocking 600,000 miles of what had once been free flowing rivers, nearly one dam built for each day since the signing of the Declaration of Independence. That’s about 17 percent of all rivers in the nation (Barker, 2007). The construction of dams changed the flow of rivers and traditional routes of Pacific salmon migration. Today, dams block almost every major river system in the West. Many of those dams have destroyed important spawning and rearing habitat for chinook, coho and other commercially important salmon runs upon which our industry depends. In some once productive salmon river systems (such as the Sacramento Valley), less than 5% of their original habitat is now still available to salmon (Barker, 2007). More specifically, in the Columbia River Basin, once the most productive salmon river system in the world, less than 70 miles of that once great river still remains free flowing (Barker, 2007). As a result, the population of Pacific salmon has dropped along with the consistent cut in the area, where Pacific salmon migrated to in the past for the reproduction and raising up youth.

1. 4 lower Snake River dams and their effects.

At this point, it is worth mentioning the fact that it Is not only the Columbia River Basin that was vulnerable to consistent changes under the impact of dams’ construction but also the Snake River Basin as well. In fact, four lower Snake River dams have changed consistently the flow, water level and temperature of the river. Naturally, these changes led t similar effects as they had on the Columbia River and the population of Pacific salmon has dropped consistently since the early 20^th century. Because salmon declines continued after 1938, when the first dam was built, and were particularly sharp after 1977, when the last Snake River dams were built, recovery efforts have focused on mitigating threats posed by the hydropower system (including warmer waters, fish-grinding turbines, and new predators) (Gross, 2008).

In response to dangerous changes in the environment and the population of Pacific salmon, state and federal authorities along with non-profit and public organizations attempted to protect the environment and to save Pacific salmon, which have become extinct today. First efforts were initiated by scientists and environmental organizations in the mid-20^th century, when the disastrous impact of dams on the population of Pacific salmon became obvious and the survival of salmon had already been under a question. These efforts helped reduce the dam-related carnage reported in the 1960s and ‘70s. But migrating salmon must also contend with habitat destruction, detrimental encounters with hatchery fish, and large-scale changes in ocean climate, which were first detected after dam construction ended in the 1970s (Gross, 2008). In such a way, the decline of the population of Pacific salmon continues, in spite of all the efforts of environmental organizations, scientists and authorities.

3. California’s Salmon and Dams
4. Central Valley Salmon Troubles.

The figure shows changes in average river flow in the Columbia River basin of the Pacific Northwest from 2069-2098. The amount and quality of river habitat is important to sustaining wild Pacific salmon populations (Chilcote, 2009). Such changes provoke the decline of Pacific salmon in the region. Dams physically limit habitat by serving as migration barriers and covering productive river floodplains under vast reservoirs (Chilcote, 2009). For instance, the 35-foot-tall concrete dam on the Wallowa Lake, which lacks fish passage, is owned today by the Associated Ditch Companies, Inc., a non-profit corporation. In 2000 the Oregon Water Resources Department declared the aging structure a “high hazard dam,” which meant it could be condemned if it is not rehabilitated (Barker, 2007). Therefore, dams have a destructive impact on the environment and provoke the extinction of Pacific salmon. The main problem is the change of the population of Pacific salmon is associated with the complex change in the coastal basin provoked by dams. In this regard, the change of the rivers’ flow, temperature and pollution of waters are major factors that provoke the decline of Pacific salmon’s population in the area.

1. Klamath Basin Salmon Controversy and Future of the River.

The Klamath River was once the third most productive Pacific salmon river system in the United States. Today, thanks to habitat blocking dams, poor water quality and too little water left in the river, the once abundant Klamath salmon runs have now been reduced to less than 10% of their historic size. Some species, such as coho salmon, are now in such low numbers in the Klamath River that they are listed under the Federal Endangered Species Act (Barker, 2007). Such a rapid decline provoked by dams forces the authorities and non-profit, environmental organizations to unite their efforts to save Pacific salmon in the area. In this regard, one of the major problem is the Klamath Irrigation Project was introduced. This is a federal project that diverts most of the water from the Upper Klamath Basin for irrigation long before the water reaches salmon spawning areas. In addition, the river was polluted by agricultural waste, including pesticides and nitrates As a result, Pacific salmon almost became extinct in the Klamath Basin. In such a situation, the future of the river is uncertain, while Pacific salmon is likely to disappear from the river that used to be the third most productive Pacific salmon river in the US.

4. Dam Removal
5. The effects of dam removal to restore salmon fisheries.

The solution of the problem of the extinction of Pacific salmon in coastal rivers lower 48 should involve the removal of dams to restore salmon fisheries. The dam removal is an essential step to restore the normal, natural flow of rivers. In addition, dam removal will help to restore the temperature suitable for salmon reproduction and minimize the impact of human activities on Pacific salmon.

1. Elwha River Dam removals inside Olympic National Park.

In this regard, the Elwha River Dam removal is one of the projects that aim at the removal of the dam to restore the flow of the river and to help to restore the population of Pacific salmon. The restoration of the river has begun successfully, although it raises economic concerns because of the impact of the dam removal on the local economy. Nevertheless, many specialists (Barker, 2007) consider environmental concerns more important than economic ones.

1. Future Dam Removals in lower 48 Pacific side rivers and waterways.

At the same time, decommissioning dams is timely and doable. Dams were never intended to last forever, and all were designed to serve for only a given engineered lifespan. In many cases these dams no longer make economic sense, particularly in the face of widespread ecological and watershed damage that must now be paid for (Barker, 2007). In fact, the removal of dams is costly but still it is necessary to the restoration of rivers and restoring the population of Pacific salmon in the area.

5. Dams really the Enemy?
6. Is Damming the main reason for salmon numbers to fall?

On the other hand, the question concerning the impact of dams arises. Today, salmon face impacts from a range of human activities. Each activity by itself will not decimate wild Pacific salmon, but the cumulative stresses that wild Pacific salmon face are daunting (Chilcote, 2009).  Salmon not only face changes in flows, but they also face deteriorated conditions, from activities such as farming and urbanization. Runoff from fields and streets contains sediment and chemicals. The clearing of vegetation for agricultural fields and the paving of cities destroys vital riparian vegetation which would usually help filter these pollutants and slow surface water runoff (Chilcote, 2009). Therefore, the overall deterioration of the environment leads to Pacific salmon extinction.

These activities also destroy lateral habitats which are important areas of the river for juvenile salmon. Lastly, urbanization and agricultural development severely limit the historical shifting habitat mosaic (Chilcote, 2009). In actuality, the figure shows the number of weeks with an average temperature greater than 21 Celsius, gernally a lethal level of salmonids (Chilcote, 2009). In response to such changes, the International Panel on Climate Change (IPCC) predicts that average global temperatures will increase by 1.5° Celsius to 5.8° Celsius by 2100 (Climate Impacts Group, University of Washington) (Chilcote, 2009). In such a way, it is obvious that dam removal alone may be not enough to solve the problem of Pacific salmon extinction because the general environment pollution and climate change affects consistently the decline of Pacific salmon population.

1. Do dams propose any benefits to Salmon?

In addition, some specialists (Gross, 2009) argue that dams may have a positive impact on Pacific salmon population. One of the recent studies (Gross, 2009) used for a direct comparison of whole-river survival estimates between the dammed and undammed rivers, the researchers also implanted smolts with acoustic tags to track them down the 910-km length of the Snake–Columbia system (Gross, 2009). Surprisingly, smolts fared just as well negotiating the heavily dammed Columbia as they did going down the free-flowing Fraser. Comparing the rivers section by section, Chinook smolts traversing the dammed system actually had higher survival rates than their cousins in the Fraser. Adjusting estimates to consider the distance and time smolts had to migrate to reach the river mouth revealed that average survival rates were much higher for both species from the Snake River than for those in the undammed Fraser. In fact, no matter how they analyzed the data, the researchers reported, “survival is not worse in the Columbia despite the presence of an extensive network of dams.” (Gross, 2009).

6. Conclusion
7. The future of salmon runs in the lower 48 rivers with dams. What we do now and what we should do more ethically.

Thus, the future of salmon in the lower 48 rivers depends on environmental policies and human activities. Obviously, the dam elimination alone will not solve the problem. The state and federal authorities should develop large scale environmental programs that can help to improve the environmental situation. Only complex measures can help to solve the problem of Pacific salmon extinction in the lower 48 rivers.