That’s not how the water system works. It’s not like all the evaporated water will end up in the lakes. California uses a lot of water for farming, it’s not like all the evaporated water ends up in the Sierras all the time. Water cycle is complex and reducing it to “it will just end up back to where it came from” is pretty reaching.
Besides it’s not just the evaporation. The leftover water concentrates a lot of the impurities that already exist in the water, and not all of it ends up in proper treatment facilities, which in turn pollutes the place wherever it ends up being. This is actually a problem in parts of Oregon.
https://www.rollingstone.com/culture/culture-features/data-c...
California is very arid, when water evaporates it rains out over the ocean or farther north. The upper mid-west is very wet and the evaporated water will come back down over the Great Lakes watershed which is enormous.
> This is actually a problem in parts of Oregon
The problem in that part of Oregon was preexisting contamination in the drinking water.
"the county’s underground water supply had been tainted with nitrates — a byproduct of chemical fertilizers used by the megafarms and food processing plants where most of his constituents worked."
Discharging a little data center water back into lake Michigan isn't going to make any difference. The entire discharge of ever data center in the world wouldn't register.
They do use evaporative cooling. A few sites aren't going to have a big impact on a Great Lake though, especially when lots of that evaporated water ends up falling in the basin.
