Maybe he means he's droughtproof for as long as he lives, which is a reasonable assumption (albeit quite selfish). After all, the Rio Grande didn't dry up over

Maybe he means he's droughtproof for as long as he lives, which is a reasonable assumption (albeit quite selfish). After all, the Rio Grande didn't dry up overnight, and for someone who was a farmer, say, 50 years ago, it was reasonable to assume that it would last their lifetime as well.