Kladeus was a river god in the Peloponnesos (Elis to be precise) which is in Southern Greece. Kladeus' domain was not great, his river was one of several tributaries which flowed into the Alpheios. It merged at a sanctuary at Olympia close to the Kytheros
Okeanos & Tethys
"At the very edge lies Cladeus, the river which, in other ways also, the Eleans honor most after the Alpheius. On the left from Zeus are Pelops, Hippodameia, the charioteer of Pelops, horses, and two men, who are apparently grooms of Pelops. Then the pediment narrows again, and in this part of it is represented the Alpheius. The name of the charioteer of Pelops is, according to the account of the Troezenians, Sphaerus, but the guide at Olympia called him Cillas."
- Pausanias, Description of Greece 5. 10. 7