Official guide
Stream Habitat Needs for Brook Trout and Brown Trout in the Driftless Area
Trout Unlimited
Quantifies the water big brown trout choose: more than about 35 inches deep, with woody debris, undercut banks or instream rock as cover. It also frames habitat as five interacting parts rather than one, which is why a stream can look right and fish poorly.
Why it made the list: Fetched 2026-09-08: PDF loads in full, Dieterman (MN DNR) and Mitro (WI DNR), 11th Driftless Area Symposium, pp. 29–44, containing the depth figure and the 75.6°F three-day-mean ceiling.
Open resource