Do not fish for the sturgeon
Start with the rule that surprises visitors. Sturgeon fishing is open all year across most of Idaho, catch and release, but the 2025 to 2027 Idaho rules carve out one exception: on the Kootenai River, fishing for sturgeon is illegal, and any sturgeon hooked by accident has to be released immediately. That means no targeting them with heavy gear on the deep bends below Bonners Ferry, even if you plan to let them go.
The reason is the fish itself. The Kootenai Tribe of Idaho explains that Kootenai River white sturgeon are a distinct stock, cut off from other Columbia River white sturgeon since the last ice age, and that they were listed as endangered in 1994. The Tribe began a conservation aquaculture program in 1989 with Bonneville Power Administration funding, and it now runs a habitat restoration program across a 55-mile reach of the river in north Idaho.
What crosses the state line at Leonia
The Kootenai enters Idaho from Montana at Leonia, which is where USGS 12305000 sits, and leaves for British Columbia past the Porthill gauge. In between it passes the Moyie River confluence and the town of Bonners Ferry, and Idaho Fish and Game's planner lists boat ramps, docks, toilets and campgrounds along the Boundary County river.
Almost everything the Leonia gauge reads is decided upstream at Libby Dam in Montana. The Kootenai Angler, the Libby, Montana outfitter at goflyfishmontana.com, notes the river was harnessed for power in 1973 and describes a tailwater with steady, cool releases that keep the fish active year round and make it largely immune to drought. That is useful to remember in August, when freestone rivers around the Panhandle are warm and low.
Reading 4,000 against 20,000
This is big water, and the flow numbers are in thousands. The Kootenai Angler's own river reports give the working scale: 4,000 cfs is the minimum flow the dam holds, fishing reports at that level describe clear water and wading chances, and at 8,000 cfs in late September 2024 they wrote that some wade fishing was available but to wade with caution. In June of 2025 the river was running near 20,000 cfs, which is boat-only water. The 4,000 to 8,000 cfs band used here comes from those reports, which quote Libby releases in Montana; the Leonia gauge adds whatever the tributaries below the dam are carrying, so read it as a little high.
The Leonia record shows why timing matters. Median monthly flows since 1971 run near 18,000 to 20,000 cfs in May and June, fall to around 7,700 in October, then climb again in November and December as the reservoir is drawn down. October is the most reliably wadeable month on the Idaho side.
Two trout over 16 inches, and the burbot
Idaho lists the Kootenai River as a special rule water in the Panhandle Region: the trout limit is two, and no rainbow or cutthroat under 16 inches may be kept. Bull trout are catch and release statewide, and the Panhandle Region is otherwise open all year. Deep Creek, a Kootenai tributary, has its own rule making rainbows catch and release from December 1 through the Friday before Memorial Day weekend.
The fish Idaho anglers sometimes forget here is the burbot. The state's certified-weight record burbot, 14 pounds, came out of the Kootenai River in 1954, and the Panhandle limit for burbot is six. Unlike the sturgeon, burbot are a legal harvest fish on this river.
Redbands and the Libby hatch calendar
The Kootenai Angler points out that the Kootenai and its tributaries hold Montana's only native strain of rainbow, Columbia redbands, known for their thick, football shape. Their monthly conditions page is the best published hatch calendar for the river, though it is written for the water nearer the dam: baetis, little blue quills and skwala in early spring, grannom and western march browns from mid-May into June, PMDs beginning in mid to late June, heavy evening PMD and tan caddis hatches through summer with green drakes in early to mid July, then blue-winged olives, tricos and October caddis in the fall. A week or two of big black carpenter ants in early summer is a local quirk worth carrying for.
Use those dates as a guide rather than a promise on the Idaho side, which no shop charts separately. The outfitter's report patterns are a sensible starting box anywhere on the river: Pheasant Tails, Princes and soft hackles below, sculpins and conehead Woolly Buggers when nothing is rising, and small Parachute Adams or PMDs for the evening.