For the guys/gals arguing about surface area...
I'm not going to argue the surface area of the dam vs. river, mainly because I think you guys are looking at the evaporation problem rather myopically. Rather, I would like to see this debate go in a new direction. It seems that water left in a hypothetically undisturbed water shed, like the Colorado, would have less chance to evaporate (while in the watershed) because it would make it to the oceans rather expeditiously. If damned....I mean dammed, I think the creation of a relatively stagnant body of water creates a rather dynamic problem for you engineering types. Based on the rate of evaporation, you would have to figure out how often a new molecular planar surface occurs. Then figure how long the exposure to the evaporative elements occurs in both models - that is the free flowing model and the dammed model. Then, I think you could solve your problem. Of course, evaporative rates are dynamic based on elemental (wind, sun, etc) exposure. One thing I know - I'm against my money evaporating into some dumb sh!t politicians hands. VOTE NO on A bad idea!!!!
Looks like you've been missing a lot of work lately.
I wouldn't say I've been *missing* it, Bob.