... would drilling a Boring Tunnel, thus making an inner ocean at Death Valley, cool down Death Valley and the inlands? Hm...
IDK:
It will also increase evaporation inland and probably increase rainfall also.
Heck, Elon can even filter out lithium from the ocean water. Win-win.
Wow -- great location, right on the water! But it looks like a fixer-upper for sure.
Nothing boring about this if you ask me, but if Elon Musk gets involved in Death Valley, you might need to move this topic over to the Hot Deals thread. 
Sultan Sea looks like another good place to drill a tunnel to. It's man-made and is very polluted without drainage into the ocean. However, looks like that would mean El Centro goes under water when ocean rises.
Problem with Sultan Sea is that the fertilizer run off and salt there keeps getting more and more concentrated. If it were connected to the open ocean, it would be much different... esp with cool ocean water coming in as water evaporates.