1) The Dams layer includes a time slider. Click thru the years since 1904 and examine the progress of dam construction along the Columbia River system. What are the oldest dams in the system and where are they located? the newest? When were the largest dams in the system built?

2) Zoom in on the four lower Snake River dams between Lewiston, Idaho and Kenniwick, Washington. Calculate the total power generating capacity of these four dams and determine what percent the total is of the cumulative power capacity determined in the worksheet.

3) One of the most obvious features of dams is to control the flow of water and, as a result, to change the character of a river. The Columbia River dams are no exception. The before and after images below give you a sense of the change. Explore the river between the dams listed in the map and through the pictures. Use the Elevation provided in the map popup for each of the dams in the table below, measure the distance between the dams, and calculate the river's gradient - the number of feet per mile that it drops - between each of the pairs of dams.

River between		Before	After	Gradient
Priest Rapid Dam & Wanapum Dam
Bonneville Dam & The Dalles Dam
		Click images to enlarge

4) The surface character of the river has certainly changed as a result of the dams. Below the surface, however, the past lingers. The pair of photos below show Celilo Falls, just upriver from the Dalles Dam. The falls were flooded in 1957 with the completion of the dam destroying the native fishing site pictured at the left. The photo on the right is a sonar image of the same site taken in 2008. Rumors persisted for years that the falls were dynamited and destroyed at the time of the flooding. Describe what the photos suggest.

Click images to enlarge

5) The perceptions that different communities of interest had and have regarding the dams on the Columbia vary as these two quotations suggest:

Elizabeth Woody - Historically, the Wyampum lived at Wyam [native village on the south side of the falls] for over twelve thousand years. Estimates vary, but Wyam is among the longest continuously inhabited communities in North America. The elders tell us we have been here from time immemorial. ¹

Today we know Celilo Falls as more than a lost landmark. It was a place as revered as one's own mother. The story of Wyam's life is the story of the salmon, and of my own ancestry. I live with the forty-two year absence and silence of Celilo Falls, much as an orphan lives hearing of the kindness and greatness of his or her mother.

Woody Gutherie - Uncle Sam took up the challenge in the year of 'thirty-three,
For the farmer and the factory and all of you and me,
He said, "Roll along, Columbia, you can ramble to the sea,
But river, while you're rambling, you can do some work for me.²

Describe and compare the values regarding the river implied in each of these quotes.

6) Use the graph tool below to explore the passage of chinook and sockeye salmon and steelhead through each of the major dams on the Lower Columbia and Snake Rivers. Describe any general patterns that you observe.