Idaho Tailwater
South Fork Boise River Fishing Report, Flows and Hatches
A cold canyon tailwater below Anderson Ranch Dam, running roughly 40 to 55 degrees year-round with heavy bug production. The salmonfly opener and the summer PMD are the marquee events, and hatch timing tracks the spring flow bump more than the air temperature.
Tailwater
Idaho
3,830 ft
Gauge 13190500
Right now
Live conditions
An expert read, in your pocket
Rivus knows your river right now. Live conditions, what’s hatching, and what to tie on, the moment you open it.
When the day turns and nothing’s working, ask Eddy and change the plan.
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The hatch chart
South Fork Boise River hatch chart
The emergences that come off the South Fork Boise by month, straight from the Rivus hatch model.
| Hatch | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Midge Midge, #18-24 | ||||||||||||
Blue Winged Olive Mayfly, #16-22 | ||||||||||||
Salmonfly Stonefly, #4-8 | ||||||||||||
Caddisfly Caddis, #14-18 | ||||||||||||
Golden Stonefly Stonefly, #8-12 | ||||||||||||
Pale Morning Dun Mayfly, #14-18 | ||||||||||||
Little Yellow Sally Stonefly, #12-16 | ||||||||||||
Flying Ant / Carpenter Ant Ant, #12-16 | ||||||||||||
Terrestrial Beetle Beetle, #12-16 | ||||||||||||
Trico Mayfly, #20-24 | ||||||||||||
Grasshopper / Terrestrial Hopper, #6-12 | ||||||||||||
Mahogany Dun Mayfly, #16-18 |
How it fishes
A Idaho tailwater
A tailwater runs out of the bottom of a dam, so the water comes out cold and steady all year. That stable temperature is why the bugs stay small and the hatches run like clockwork, and it is why the fish grow picky and well fed. The flip side is that the dam sets the flow, not the weather, so a release can change the river overnight. You read the gauge, not the sky.
Flow and gauge
Reading the flows
The South Fork Boise is metered at USGS gauge 13190500. Watch the trend as much as the number: a river that is dropping and clearing fishes very differently from one that is coming up.
Access and regulations
Before you fish
Access and the right to fish are the angler’s responsibility, every time. Public access, private water, and seasonal closures vary along the river, so confirm where you can legally stand and wade before you go. We do not point you to a specific spot.
Read the current rules, license requirements, and any special-regulation water before you go. Regulations change season to season, so check them fresh.
Flow and water temperature from USGS, weather from NWS and NOAA, refreshed hourly. Real-time USGS readings are provisional and subject to revision. The hatch chart and river read are Rivus model output.