Zalewski (feminine: Zalewska, plural: Zalewscy) is a Polish-language surname. The surname comes from a topographic name for someone who lived by a flood plain, bay, or any other small body of water. Two locations that this may be connected to are Zalew in Sieradz voivodeship or Zalewo in Olsztyn voivodeship. The Germanised version of this surname is Salewski, usually found in the Silesia region. . An early form of this surname was first noted in the year 1370. Many families from different classes and with different background used this surname.
https://en.wikipedia.org/wiki/Zalewski