North Fork, South Fork, and main stem. Dates shift a week or two either way with snowpack and spring temperatures.
Streamflow right now
Live from USGS. Runoff, not the bug list, is usually what decides whether a day is fishable.
North Fork · Enaville
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USGS 12413000
Main stem · Cataldo
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USGS 12413500
Medians from ~88 years of record at Enaville and ~94 at Cataldo. Full hydrographs:
Enaville ·
Cataldo
Water temperature
Hatch timeline
Shading is intensity, not presence — a peak month means fish are keyed on it and it's worth building your day around.
Peak — best Active Fringe — spotty Not a factor
Darker = better fishing on that fly. The pale blue band marks the current month — it's a "you are here" marker, not a rating.
Tap any month for hook sizes and fly patterns.
May and June are shaded gray in the month row — that's typical runoff, when clarity and access, not the hatch, are the limiting factor.
Month by month
What's happening, what the river is doing, and what to tie on first.
Before you go
Runoff is the real constraint, not the bug list. Roughly May through mid-June the river runs high and off-color. The hatches happen regardless; whether you can fish them depends on the year's snowpack. Check flows before you drive.
In midsummer, fish mornings only. By mid-August the upper North Fork runs very thin and afternoon water pushes past 68°F, where playing a cutthroat can kill it even on a careful release. Carry a thermometer. At 65°F and climbing, go home.
Salmonflies are spotty here. They're real but reach-specific, and local shops put the hatch a month earlier than most online charts. Golden stones and yellow sallies are the dependable big-stone story.
The South Fork below Wallace is a diminished fishery. A century of Silver Valley mining left the corridor loaded with cadmium, lead, and zinc; surveys found a handful of invertebrate taxa there against 25–32 in the North Fork. Superfund work continues. Above the Wallace–Osburn stretch it fishes fine.
No harvest of any trout with a red or orange slash below the jaw anywhere in the drainage — that's the native westslope cutthroat. The Little North Fork above Laverne Creek is no-bait, barbless. Confirm current rules with Idaho Fish and Game; this page is not a regulations document.