Complex sentence: The remaining timbers were given to the City of Myrtle Creek in 1990 for a covered bridge over Myrtle Creek, a tributary of the South Umpqua River.
Split into simpler sentences: The remaining timbers were given to the City of Myrtle Creek in 1990 for a covered bridge over Myrtle Creek. The creek is a tributary of the South Umpqua River.