The Great Hydration — Barrington J. Bayley

Karl Krabbe and Boris Bouche, partners, explorers, interstellar chancers, don't care much for the law. They don't care much for anything - except profit. Their staff bondman nuclear engineer Roncie Northrop doesn't care much about anything either, except that he's already tried to abscond from the control of the rapacious and illegally operating pair once.

When K&B's exploration ship comes upon the small planet Tenacity, they see a good business opportunity. Tenacity is waterless, a desert planet. But it had water once, and they realize that with some adroit but spectacular geological engineering it can be given its oceans back. That suits the dominant lobster-like Tlixix fine. They are tired of living like aliens in their domed refuges. Of course, the numerous intelligent species which have evolved since the great dehydration will perish, but so what? As for Roncie, whose part in the project is crucial, he doesn't like it much, but what can he do? He's only a bondman.

Krabbe and Bouche strike a deal, and business is business...