[jwsea55]

I think that S.F. gets all of its electrical power from generators whose turbines are powered exclusively by Hetch Hetchy water.

That is what the article said. In reality, the power travels down transmission lines is generally sold to the nearest buyer to avoid transmission power losses and transmission costs. Agencies and power companies, essentially, swap production to avoid these costs.

[old school]

What happens when you’ve got nuthin’ to swap?