Big Mallard Rapids is a stretch of rapids in Idaho County, Idaho, in the Idaho Batholith region. It lies about 49.1 miles southeast of Grangeville and roughly 110.5 miles southwest of Missoula as the crow flies.
The Idaho Batholith is a maze of steep granite mountains and deep canyons blanketed by lodgepole and ponderosa pine and Douglas fir, with some of the largest roadless areas in the lower 48. Rivers here are wild and fast, dropping through rocky gorges.
Idaho County holds 65 recorded rapids, and several are close by. Little Mallard Rapids, is about 1.6 miles away. Split Rock Rapids, is about 1.8 miles away. Fivemile Rapids, is about 2.3 miles away.
Big Mallard Rapids is located at 45.5381° N, 115.2688° W. The listing is based on the USGS Geographic Names Information System, one of the sources compiled by the U.S. Geological Survey in its inventory of waterfalls and rapids of the conterminous United States. The position was verified on aerial imagery. Details on trails, parking and access have not been documented for this rapid yet.