Public Sites
| State | County | Name |
|---|---|---|
| Iowa | Adair | Orient |
| Missouri | Camden | Osage Beach |
| Iowa | Clayton | Osborne Outdoor Education Center Park |
| Iowa | Clayton | Osborne Pond |
| Florida | Sarasota | Oscar Scherer State Park |
| Iowa | Osceola | Osceola County |
| Iowa | Mahaska | Oskaloosa |
| Iowa | Allamakee | Osterholm Site |
| Iowa | Webster | Otho |
| Iowa | Woodbury | Oto |
| Iowa | Mitchell | Otranto Park |
| Iowa | Mitchell | Otranto Wildlife Area |
| Ohio | Ottawa | Ottawa National Wildlife Refuge |
| Iowa | Osceola | Otter Creek @ 190th Street |
| Iowa | Osceola | Otter Creek @ A34 |
| Iowa | Osceola | Otter Creek @ Oriole Ave |
| Iowa | Warren | Otter Creek County Park |
| Iowa | Tama | Otter Creek Lake and Park, Tama County |
| Iowa | Tama | Otter Creek Marsh |
| Iowa | Linn | Otter Creek Natural Area |
| Iowa | Crawford | Otter Creek Nature Area |
| Iowa | Buchanan | Otter Creek Roadside Park |
| Iowa | Humboldt | Ottosen Potholes Wildlife Area |
| Iowa | Wapello | Ottumwa |
| Colorado | Ouray | Ouray |