Fishing Island Park Reservoir in Fremont County, Idaho

• Overview

  Set in Fremont County, Island Park Reservoir is an Idaho water. The ground around here is pine and birch. It covers about 11.8 sq miles, which means weather matters as much as tactics. You have roughly 51 miles of edge to choose from, which rewards a scouting trip. Nothing else we list in Fremont County covers more water. Head to Ashton, 23 miles away, for anything you forgot. Billings is the closest city, 175 miles away. It lies deep inside the county rather than near an edge.

• Where to Fish on Island Park Reservoir

  Nothing we hold settles how deep this runs. The old creek line under the surface is the feature worth finding. A reservoir gives you a hard edge, a shelf, and not much else. Open biodiversity records for Fremont County list rainbow trout, cutthroat trout, brook trout and sockeye salmon. Some of the species recorded here are protected or tightly regulated, so check what may be targeted before you fish. The near bank of Island Park Reservoir is often the one people ignore.

• Seasonal Patterns

  Temperature averages peak at 60°F in July and bottom out at 14°F in January. Fishing here follows the temperature more than the calendar. The lid usually goes in late April, which opens the strongest weeks of the year. Open water usually runs from late April until about mid November. Early summer and early autumn carry the open-water season. The season on Island Park Reservoir rarely departs from it.

• Tackle & Baits

  Public data does not answer the access question here. There is no mapped parking or launch close by, which usually means walking in. For the trout, small spinners and a box of nymphs cover both approaches. Take the rules with you rather than trusting memory. Signs go up and come down, so check on the day. Golden Lake, 3.5 miles away, makes the obvious fallback. For Island Park Reservoir in particular, ask before you travel.