Blazon: Gules a chevron argent
It looks like the town of Nehren adopted the arms of the von Nehrens, a noble family who ruled in the area from at least 1305 through 1441. The arms allegedly originated with a Lescher family, but I can’t find any solid evidence for that. (I’ve found plenty of records of Leschers, but none with an associated blazon or depiction of arms.) Nehren’s website does feature a lovely depiction of their arms in begonias; one of the advantages of simpler arms.