Lab 4

Marmot Dam Removal  in Sandy River

What is a Dam?

Is a barrier built across a  river and stream. it is usable for different human purposes such as irrigation and generation of hydroelectricity. Human have reason to build a dam and these are; generation of hydroelectricity, irrigation, (this stop a river's natural course and water can go in different way), control flooding (these are called detention dams, which can stop or slow the amount of water. "There are, three main types of dam design : embankment, gravity and arch selected mainly according to dam–site topography and geology".  (S.H.C. de Silva 1991)

History of a dam in Sandy river

The Marmot Dam was build in 1930 and destroyed in 2007 . "The dam was built to block the main upper (easternmost) channel, allowing all flow to enter the Columbia at the lower mouth" (Portland Hikers Field Guide website 2009). it is one of  the largest dam removed in the Oregon history, and it took seven years to build it. The water comes from Mt. Hood and goes to the Columbia river.

Reason of the destruction of the Dam?

After the explosion about 23 organization took the decision to wait for the rain season to wash the sediments, because they said " it is a natural sediment, and doesn't contain any toxic element. It was destroyed in 2007, and the main reason was the fishes freedom meaning that fishes can go and back in the river, without any barrier that can stop them . Many organization contributed with this project, however Portland General Electric host a destruction party.

Vegetation Type along the place where was the dam

There is a secondary succession because the soil was already there however some people whom work for the Sandy river conservation had add some fertilizes, and some nutrients to soil to grow plant or conifers. In one place near to the dam the soil is a little compact , but in the other side there is a beautiful forest where are a lot conifers trees, sword ferns, the canopy is very open so the sun can heat the floor. The forest floor is cover by woody debris, and the color is reddish and soft. I couldn't see any signal of wildlife. The forest is very thick, and I identified that trees are the primary and I saw trunks that were in the process of decomposition by fungi who are the decomposes.

 

What people are doing to after the dam was removed?

There  are people have done a lot restorations  projects; Because of the type of soil after the dam was removed they had to add some nutrients or fertilizes to soil, removed invasive plants like blackberries. About  reforestation project, by knowing the type of soil they have been planting some conifers trees, and I saw them in a very good growing. All of this work they were able to finish with some organizations , a lot volunteers work from some high school, however they still working in these projects. Some of the futures plans are to continue planting trees, create a kiosk of information and many different things.   

References : 

• Patrick McCully’s. 1991. The Ecology and Politics of Large Dams International Rivers people.water.life.  Available in internet from : http://www.internationalrivers.org/dams-what-they-are-and-what-they-do  01/31/2014
• Portland Hikers Field Guide website.  2009. Sandy River Delta Oregon. The Columbia River . Available in internet from: http://columbiariverimages.com/Regions/Places/sandy_river_delta.html 01/31/2014 

Images References:

https://www.google.com/search?q=dam+removal+sandy+river&source=lnms&tbm=isch&sa=X&ei=5kfwUvmnLcKHogSvwYDIBg&ved=0CAkQ_AUoAw&biw=1366&bih=667#imgdii=_