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Dam Removal?


Dam removal and restoration of the Hetch Hetchy Valley was first seriously proposed in 1988 by Donald Hodel, President Bush's Secretary of the Interior. Hodel's proposal has been followed over the last two decades by a series of increasingly more comprehensive studies by a variety of groups and agencies including:
• Environmental Defense
• Restore Hetch Hetchy
• California Departments of Water Resources and Parks & Recreation
• US Department of the Interior

The activity below provides an opportunity to explore the existing San Francisco water and power system, to glimpse into the conclusions of the studies listed above and the data on which they are based, and, finally, to weigh the pros and cons of dam removal and formulate your own position.

Water & Power for San Francisco

To say that the impact of removing O'Shaughnessy Dam on San Francisco's water and power system would be significant would be a gross understatement. The existing system serves water and power needs not only in the city, but several other Bay Area communities as well, provides power to meet San Francisco's public utility needs and those of the Turlock and Modesto Irrigation Districts, and provides flood control and irrigation to Sacramento and San Joaquin Valley farmers and towns. To begin to understand the impact of dam removal you need a basic understanding of the existing system. The San Francisco Water System - 2011 page contains several layers of maps and related data. Take a look.

As you can see the system is composed of a variety of pieces:

• dams and reservoirs in the Sierras to capture and hold mountain run off
• power plants for hydroelectric power generation
• pipelines and tunnels to convey water to the Bay Area
• treatment plants for water coming out of the California Coast Range
• holding reservoirs in the East Bay and in San Francisco


To Start You Thinking -

1) Where are the largest dams in the system? What is their total storage capacity? Not all of the water stored in the system's reservoirs goes for drinking water. You may have noticed when you click on Don Pedro Dam that it is owned by the Turlock Irrigation District. San Francisco has rights to 740,000 acre feet of water per year. The remainder is for irrigation. What is the adjusted total available to San Francisco?

Google Maps

* Map layers turn Off and On by clicking the available checkboxes:

Checkboxes Here

• Switch between the different resource tables and graphs by clicking on the appropriate button:

Radio Button

• Click on the headings in the tables to sort the data up or down.

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2) What is the average age of the systems major dams? power plants?

3) Locate the three power plants in the system. What is the total average power output in millions of kilowatt hours (MkKh)? The total possible power output in California is approximately 325,000 millions of kilowatt hours per year. What percentage of this total does each of the plants in the San Francisco system provide?

4) Treatment of water in the San Francisco system is minimal because of the purity of most of the water at its source in the Sierras. Where are the two treatment plants in relation to sources outside the Sierras?

5) The pipe and tunnel pieces of the system are extensive. How extensive? The map you have is not exact in terms of the location of each section of tunnel and pipeline. You can, however, use the map scale to estimate the total length of pipeline and tunnels that bring water across the state to the Bay Area.



Putting the Pieces Together

The issues around the removal of O'Shaughnessy Dam and restoring Hetch Hetchy Valley are complex. Analysis is well served by teamwork on both sides of the issue -- pro and con. The diagram at right suggests a division of the effort. Click on the headings for outlines of the responsibilities of team members and for descriptions of each piece of work that needs to be produced leading to a class debate. There is a bibliography of possible resources that address the issue from both sides of the argument.

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Take a Stand

The final piece of this activity is for you to weigh in on the issue personally. Write an opinion piece (e.g. - a letter to the editor or a Congressional leader, a newspaper op-ed article) in which you argue for or against dam removal. Support your argument with any of the evidence gathered as part of the debate. Check the evaluation guidelines for the assignment.


image by permission of Brooks Anderson, BrooksAndersonArt.com "Hetch Hetchy: Requiem for a Valley," in the collection of Principia College, Elsah, Illinois.
Last modified in January, 2011 by Rick Thomas