Pettit Lake, Glacial lake in Blaine County, Idaho, United States

Pettit Lake is a large alpine lake in the Sawtooth Valley of Blaine County, Idaho, about 16 miles south of Stanley and 33 miles northwest of Ketchum. It lies at 6,996 feet just east of the Sawtooth Wilderness, the third largest lake in the Sawtooth National Recreation Area, roughly 1.1 km wide north to south and 2.7 km long east to west.

The lake took shape during the last Ice Age when glaciers carved a deep basin into the valley below. This glacial sculpting created the steep walls and granite formations visible today around the shoreline.

Pettit Lake is a destination for anglers, with fishing traditions focused on Kokanee salmon, Rainbow trout, and Bull trout. Each species has specific catch regulations, and the lake is a popular spot for fishing in the Sawtooth Valley.

The lake is easily reached by hiking trails and forest service roads that connect to the main highway nearby, with camping areas scattered through the surrounding forest. Plan for cooler temperatures and changing weather conditions due to the high elevation.

The water from this lake flows into neighboring water bodies through a chain of natural connections, becoming part of a larger river system. Few visitors realize how this small alpine lake feeds into downstream ecosystems many miles away.