Riga was a 24th century Monean scientist, living on The Waters.

When USS Voyager visited this planetoid in 2375, Riga joined Deputy Consul Burkus to visit Voyager, where he revealed their ocean was losing containment. Riga then accompanied Tom Paris and Harry Kim aboard the Delta Flyer to travel to the planetoid's center, where they discovered that the Moneans themselves were responsible for the containment loss by using several oxygen refineries. Riga recommended to take several refineries offline and was asked to write a full report for the subcommittees on agriculture and life support, but did not believe the Monean authorities would follow his suggestions. He and Paris then tried to destroy such a refinery with the Delta Flyer, but were stopped by Voyager. (VOY: "Thirty Days")

Riga was played by Willie Garson.