Idaho · Freestone · Rockies
Big Lost River — Arco
High-desert river; lower reaches can run low. Verify current flow.
Idaho · public-access reaches. This page is what the desk knows about the water itself. What it is doing today — flow, water temperature, weather, and the hazards those produce — is a reading with a date on it, and it lives in Trip Prep.
Plan a trip on Big Lost River — ArcoWho manages it
Idaho Department of Fish and Game
These links were checked against the live agency site on 2026-09-01. Rules for a water change inside a season, so the agency’s own page on the day you go is the only current answer — this desk does not hold one.
Directory review
Review provenance unavailable
No unique fleet-directory record matched this operational water by name and state, so the desk will not borrow another water’s review date. The agency links on this page were checked on 2026-09-01; check the agency’s own page the day you go.
How access works here
Road-adjacent public reaches
Freestone reaches on this list are generally reached from a road that runs the valley — bridge crossings, pullouts and public-land frontage. Between those, ownership changes without a sign.
Launch · Hand-launch for a raft or small drift boat at bridges and pullouts where it is legal. Confirm the take-out before you push off; a freestone take-out can be a long way down.
Parking · Parking is at designated access points. A pullout that looks fine is not automatically legal or safe to leave a vehicle in.
Idaho publishes access points and boat ramps in the Fishing Planner map centre. Many reaches are reached from public road right-of-way or Forest Service land.
Gauge
A public gauge is mapped
Flow and water temperature for this water are read from USGS site 13132500, Big Lost River near Arco, ID. It is an official public gauge, not a fishing pin: it describes the river at one point, and the reach you stand in may be doing something else.
Species · derived
6 plausible here
Derived from water class (freestone) and Rockies range — not a stocking record. Confirm species, seasons and any closures with Idaho Department of Fish and Game.
Brown trout
54–67°F published preference · handling becomes a conservation problem at 68°F
Rainbow trout
52–64°F published preference · handling becomes a conservation problem at 68°F
Cutthroat trout
48–62°F published preference · handling becomes a conservation problem at 66°F
Brook trout
46–61°F published preference · handling becomes a conservation problem at 65°F
Mountain whitefish
46–64°F published preference · handling becomes a conservation problem at 68°F
Steelhead
46–61°F published preference · handling becomes a conservation problem at 70°F