Water, water, everywhere but not a drop to spare!
I've heard about seeding clouds to produce rain. I understand that Middle Eastern countries, including Israel, have used desalination for primary water sources.
Let's make the leap to a new water technology. When the Japanese overtook the Pacific in WWII and the rubber plantations, western military forces quickly went to synthetic tires. Given rising ocean levels, I bet Los Angeles could single-handedly use enough ocean water to reduce flooding in low countries.