Major UP river system with multiple branches. Steelhead and brown trout in lower sections; brook trout in the headwaters. Ottawa National Forest surrounds much of the river.
Species present: Brook trout, Brown trout, Steelhead trout. Stream type: freestone.
Based on current water temperature and time of year, the following insects are active or expected on the Ontonagon River.
| Hatch | Latin | Top Patterns | Time of Day |
|---|---|---|---|
| Sulphur | Ephemerella dorothea / invaria | Sulphur Comparadun #14, Sulphur Parachute #14 | evening |
| Light Cahill | Stenacron interpunctatum | Light Cahill #14, Cream Comparadun #14 | evening |
| Hexagenia (Hex) | Hexagenia limbata | Hex Wiggle Nymph #4, Extended Body Hex Dun #4 | night |
| Trico | Tricorythodes spp. | CDC Trico Spinner #20, Trico Dun #20 | morning |
| Terrestrials | Beetles, ants, hoppers, crickets | Foam Beetle #12, Chernobyl Ant #10 | afternoon |