Question: The refuge for a historically significant herd of free-roaming Mustangs is close to what lake? 
Sentence (from "Pryor Mountains Wild Horse Range"): The Pryor Mountains Wild Horse Range is a refuge for a historically significant herd of free-roaming Mustangs, feral horses colloquially called "wild horses", located in the Pryor Mountains of Montana and Wyoming in the United States.
Relevant evidence: Yes