The Mamonovka or Banovka (, , ) is a river between Russia (Kaliningrad Oblast) and Poland (Warmian-Masurian Voivodship). It flows into the Vistula Lagoon. It is 51 km long and has a 311 km<sup>2</sup> drainage basin.
The Ignatievka River and the Vitushka River are tributaries of the Mamonovka.