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 |
|---|---|---|---|
| Midge | Chironomidae | Mercury Midge #20, Zebra Midge #20 | midday |
| Little Black Stonefly | Capniidae / Leuctridae | Little Black Stonefly #14, Black Stonefly Nymph #14 | afternoon |
| Blue-Winged Olive (Baetis) | Baetis spp. | Parachute BWO #16, Sparkle Dun BWO #16 | midday |
| Hendrickson | Ephemerella subvaria | Hendrickson Dry #12, Red Quill #12 | afternoon |
| Early Brown Stonefly | Rhyacophilidae | Elk Hair Caddis (brown) #14, Hare's Ear Nymph #12 | morning |
| Grannom Caddis | Brachycentrus spp. | Elk Hair Caddis #14, X-Caddis #14 | afternoon |