Water is cold. Rainbows are spawning in the mainstem river and its tributaries. Some discoloration expected in this period due to runoff entering the Kootenai River from tributaries below Libby Dam. Some good early streamer and nymph fishing. Some dry activity on sunny days. Blue-wing Olive (Baetis), Iron Dun (Little Blue Quill, Olive Stone (Skwala), Little Yellow Stone, Midges
Water begins to warm in May and the early caddis and mayflies begin to emerge. The Grannom caddis and Western March Brown generally appear in mid-May to early June. Dry Fly fishing starts to "turn on" throughout the day. Mid to late June usually marks the beginning of the Pale Morning Duns. There is also a week or two during this time is which giant Black Ants coat the water making for some good terrestrial fishing. Some large fish are caught on streamers as they come off the spawn. Grannom Caddis, Western March Brown, Pale Morning Duns, Blue-wing Olive, Iron Dun, Yellow Cranefly, Black Ants, Sporadic Green Drakes. Smaller tributaries open 3rd Saturday in May and remain floatable till 2nd week of July during an average snowpack year.
Prime dry fly fishing. Heavy, consistent late afternoon and evening hatches of Pale Morning Duns and Tan Caddis. Green Drakes in early to mid-July. Excellent dry fly fishing on attractor patterns early in the day and between hatches. Water temperatures are their warmest and fish are very active. Late evening Caddis emergences and egg laying produce some very exciting dry fly fishing. Hopper fishing begins. Tan Caddis, Pale Morning Dun, Blue-wing Olive, Hoppers (small)
Beautiful fall colors and crystal clear water. The Kootenai is transformed into Montana's largest spring creek. The river's glacier fed water is now in its purest form, underwater visibility commonly reaches depths of 20 feet or more. Cool nights and shortened days produce day-long dry fly conditions. Fish feed voraciously, storing up for the coming winter. Soft casts and delicate presentations are often required. A wide range of dry fly activity ranging from a #8 Cinnamon Sedge to a #24 Little Blue Quill. Blanket hatches of Blue-wing Olives on overcast days. Tan Caddis, Little Blue Quill, Blue-wing Olive, Tricos, Green Chironomids, Cinnamon Sedge (October Caddis), Hoppers. Waterfowl season begins. Combine dry fly fishing with waterfowl hunting.
An often-overlooked time of the year, when freestone streams cool off and fishing shuts down. However, on large dam-controlled tailwater fisheries such as the Kootenai, the season is extended due to the ability of selective withdrawal to release warmer water. Water temperatures remain in the 50's through this period and fish are still very active. Some exceptional waterfowl hunting.