Lab # 4

Dam Removal and Sediment Transport in the Sandy River Basin, Oregon

The Sandy River is a 56-mile (90 km) tributary of the Columbia River in northwestern Oregon in the United States. Measured by a United States Geological Survey (USGS) gauge downstream of the Sandy's confluence with the Bull Run River, 18.4 miles (29.6 km) from the mouth, the river's average discharge is 2,300 cubic feet per second (65 m³/s). The maximum daily recorded flow is 84,400 cubic feet per second (2,390 m³/s), and the minimum is 45 cubic feet per second (1.3 m³/s).^[6] The Sandy joins the Columbia about 14 miles (23 km) upstream of Portland. (Brinckman, Jonathan (October 12, 2002).  http://en.wikipedia.org/wiki/Sandy_River_(Oregon)

 

Dam Removal

The dam was removal in 2007. The dam was a barrier for some wildlife such as fish because with pressure of that dam the fish can’t go back and forth. Also was less genetic diversity and store the fish. Some of the benefits were free flow and the fish can have a free environment to live without barriers. Now naturally flowing without dams from its water source at Mount Hood, the river flows to the mighty Columbia River. The Sandy River offers paddlers and other excellent opportunities just minutes from the greater Portland area.

After the dam was destroyed the people who manage the river start to find different strategies to keep the river clean and preserve the vegetation and wildlife that we can find there. Some of the strategies have been doing are for example to reforest the area near where the dam, connect a corridor with different path for the wildlife, all the activities they have done were with volunteers. The whole area is secondary succession because the soil already exist, but in areas the soil is been compact because the human’s activities.

 Some of the big reforestation projects were in 2010. In 2007 they did an experiment to see which kind of vegetation can grow in this area and after that they start to have reforestation projects. When the dam was destroyed, it does not affect too much the wildlife because it was so rapidly. In some part where the dam was now is present a little bit of soil erosion but that is okay because it is natural.

In this area we can find two different type of forest because one of them looks like there are just young trees, no too much woody debris, and the soil has not too much nutrients but still been a nice forest. The other part is a total different forest because we found that in this area is present lots of woody debris, and the soil has lots of nutrients and as a result this area has more vegetation.

In the 1930s, the Oregon Game Commission redirected the main branch of the Sandy River, also known as the East Channel, in an attempt to improve fish runs. A 750-foot long dam was constructed on the East Channel to direct water flow toward the West Channel of the Sandy River. (http://www.nwp.usace.army.mil/Missions).