Conditions
High flows across the Big Lost will dominate the week ahead, making wading unsafe and limiting access through mid-June. The upper reaches offer scenic scouting opportunity while flows remain elevated. As levels drop below 350 cfs, the lower section below Mackay should become wadeable and worth returning to. Foundation patterns include PMDs, Baetis, midges, and stoneflies once conditions stabilize.
Gauges
Live cameras
Big Lost River below Inlet Diversion near Arco
USGS 13132520 · Oct 18, 2026, 5:00 PM
Every 60 min · daylight
Big Lost River near Arco
USGS 13132500 · Oct 18, 2026, 5:00 PM
Every 60 min · daylight
Big Lost River near Leslie
USGS 13130300 · Oct 18, 2026, 5:00 PM
Every 60 min · 247
Big Lost River bl Mackay Res nr Mackay
Last updatedUSGS 13127000 · Nov 7, 2025, 10:00 AM
Every 60 min · 247
Recommended flies
PMDsStonefliesBaetis 18, 20Midge 20–24Streamers
Access
Scout the upper Big Lost and its scenic valley during high-water periods when wading is unsafe. The lower section below Mackay will become accessible as flows recede below 350 cfs.
Safety
Wading is unsafe above 500 cfs on the lower Big Lost. Wait for flows to drop significantly before attempting to wade.