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Reservoir and Dam Removal

Reservoir and Dam Removal. Orrin Babcock. Outline. Purpose of Dams Number of Dams in America Dam affect on the environment Selected publication Conclusion. Purpose of Dams. A barrier constructed across a waterway to control the flow or raise the level of water.

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Reservoir and Dam Removal

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  1. Reservoir and Dam Removal Orrin Babcock

  2. Outline • Purpose of Dams • Number of Dams in America • Dam affect on the environment • Selected publication • Conclusion

  3. Purpose of Dams • A barrier constructed across a waterway to control the flow or raise the level of water. • freshwater reservoirs, fish hatcheries, hydropower, recreation, irrigation, navigation, and flood control

  4. In the United States there are 84,134 dams

  5. Environmental Effects • River’s natural course and flow • Limits species present • Water temperatures in the stream

  6. Environmental Effects • Redirect river channels • Tennessee Valley Authority (TVA) regulates the Ocoee River • Disrupt river continuity • Fish ladders

  7. Environmental Effects • Transform floodplains • Sediment Buildup

  8. Selected Publication • “Trading off: the ecological effects of dam removal” by Emily H Stanley and Martin W Doyle 2003 • Study looked at dam removal in the state of Wisconsin • Size and geographic limitations can be ignored; results should apply for all sizes and areas.

  9. Dam Removal • Species change within two years • Reservoir to riverine species • Less Common Carp, more bass and darters

  10. Export of Sediments • http://video.nationalgeographic.com/video/player/news/environment-news/us-condit-dam-breach-vin.html Elevated levels of sediment can last from days to months depending on the size of the reservoir

  11. Export of Sediments • Fort Edwards Dam • 1st portion removed in 1973 • Led to elevated levels of polychlorinated biphenyls (PCBs) and oils • Clogged Hudson River • 2nd portion removed in 1991 • PCB’s doubled in striped bass

  12. Export of Sediments • Sediments can be nutrient enriched due to agriculture • Sedimentation can have affects as far as 12km downstream

  13. Removal is a Trade-off • Dams separate wild and farm raised fish • Keeps the gene pools clean • Removal restores the stream to its original state • It also increases the sediment load and can scour parts of the bank • Best to remove them before they fail • Save human lives

  14. Conclusion • Recent survey of 10 000 flood control dams, over 2200 sites were in need of maintenance • The best case scenario for dams that generate limited revenue is to remove them, rather than spend the money to rebuild or repair them.

  15. Personal Conclusion • Respect Nature, If we didn’t have the desire to live so close to rivers we would have no need to dam them for flood control.

  16. Questions?

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