Does Upper Big Creek hold wild trout?

Yes. The state classifies Upper Big Creek as Class I (wild, self-sustaining) across 5.46 miles of stream. That classification means natural reproduction, not stocking. Source: Wisconsin DNR Classified Trout Streams.

Upper Big Creek, Wisconsin: Wild Trout

State Trout Classification

Classification	Class I (wild, self-sustaining)
Classified length	5.46 miles

Source: Wisconsin DNR Classified Trout Streams.

Fly fishing rivers →Wisconsin trout water →Wisconsin lakes →

Conditions: USGS NWIS (public domain). Classification: Wisconsin DNR Classified Trout Streams.