Wikipedia
Oelse (Oder-Spree)
The Oelse is a river in the district Oder-Spree, Brandenburg, Germany. It is situated in the Schlaube Valley Nature Park and runs from the Möschensee (lake) in the east from Groß Muckrow (part of Friedland) to the river Spree nearby Beeskow. Its name derives from the sorbian ol'ša for German Erle ( Alder).