A mammoth solar farm is moving forward in the heart of California. If built, which seems increasingly likely, it would cover 200 square miles of land and generate 21,000 megawatts of electricity, enough to power entire cities. Huge batteries will store some of that power until it’s needed most. Farmers are among the project’s backers. … These farmers are now facing a new water crisis. The canal has been delivering less water in recent years because of droughts and competing claims on that water. Until recently, the farmers had a backup water supply: They could pump water from aquifers a thousand feet underground. Now, though, a new state law is coming into force that bans overpumping from the aquifer.