Winding River is a small area behind Carter Hydro Dam that connects Mystery Lake to the cave then subsequently Pleasant Valley. It is part of the transition zone called the Carter Hydro Dam & Environs.
The area connects to the Carter Hydro Dam via two one-way paths, the exit being a door, and the entrance to the dam being a broken window on the other side of the dam. The window is accessible by passing the ledge.
Before the Faithful Cartographer update there was only one wolf in this zone and Fluffy in the Dam. Then starting in Rugged Sentinel there were two wolves the second one being Fluffy free from the Dam. Finally in Hesitant Prospect only one wolf lives here implying that the Darkwalker might be Fluffy.