There are 27 unique ditch names beginning with O:

O'Brien Ditch	O'Brien Ditch Repair	Oak Run (Styer) Ditch	Oak Run Branch Ditch	Oehler Ditch	Ogan (Elliott) Ditch	Oglesbee Ditch
Ohnsman Ditch	Olive Run Ditch	Oppihle Ditch	Orahood Ditch	Orahood Joint Ditch	Orchard Place Ditch	Orders Ditch
Ottawa Branch (Stevenson) Ditch	Ottawa Branch Ditch	Ottawa Branch Ditch Repair	Ottawa Joint Ditch	Ottawa Run Ditch	Ottawa Run Ditch - Richwood Branch	Ottawa Run Joint Ditch
Ottawa Street Ditch	Ottawa Tile Ditch	Otter Run Ditch	Otto Howard Joint Ditch	Outback Golf Club Group Mutual Agreement Ditch	Owens Ditch