Question: The refuge for a historically significant herd of free-roaming Mustangs is close to what lake? 

<P0-S0> The Pryor Mountain Mustang is a substrain of Mustang considered to be genetically unique and one of the few strains of horses verified by DNA analysis to be descended from the original Colonial Spanish Horses brought to the Americas by the Spanish. <P0-S1>  They live on the Pryor Mountains Wild Horse Range located in the Pryor Mountains of Montana and Wyoming in the United States, and are the only Mustang herd remaining in Montana. <P0-S2>  They are protected by the Wild and Free-Roaming Horses and Burros Act of 1971 (WFRHBA) and managed by the Bureau of Land Management (BLM), who has set the optimum herd number at 120 animals. <P0-S3>  Genetic studies have revealed that the herd exhibits a high degree of genetic diversity and a low degree of inbreeding, and BLM has acknowledged the genetic uniqueness of the herd. <P0-S4>  Pryor Mountain Mustangs are relatively small horses, exhibit a natural ambling gait, and domesticated Pryor Mountain Mustangs are known for their strength, sure-footedness and stamina. <SEP> <P1-S0> 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. <P1-S1>  The range has an area of 39650 acre and was established in 1968 along the Montana–Wyoming border as the first protected refuge dedicated exclusively for Mustangs. <P1-S2>  It was the second feral horse refuge in the United States. <P1-S3>  About a quarter of the refuge lies within the Bighorn Canyon National Recreation Area. <P1-S4>  A group of federal agencies, led by the Bureau of Land Management, administers the range. <SEP> <P2-S0> Medicine Lake National Wildlife Refuge is a 31533 acre National Wildlife Refuge located in the northeastern region of the U.S. state of Montana. <P2-S1>  The refuge is part of the Medicine Lake National Wildlife Refuge Complex which also includes the Northeast Montana Wetland Management District (WMD) and Lamesteer National Wildlife Refuge. <P2-S2>  Medicine Lake is from the Assiniboine description of the lake, "Bda wauka" (medicine water). <P2-S3>  The refuge was established in 1935 to protect habitat for various wildlife and especially migratory birds. <P2-S4>  The refuge is managed by the U.S. Fish and Wildlife Service, an agency of the U.S. Department of the Interior. <SEP> <P3-S0> Bighorn Canyon National Recreation Area is a national park unit established by an act of Congress on October 15, 1966, following the construction of the Yellowtail Dam by the Bureau of Reclamation. <P3-S1>  It straddles the border between Wyoming and Montana. <P3-S2>  The dam, named after the famous Crow leader Robert Yellowtail, harnesses the waters of the Bighorn River by turning that variable watercourse into Bighorn Lake. <P3-S3>  The lake extends 71 mi through Wyoming and Montana, 55 mi of which lie within the national recreation area. <P3-S4>  About one third of the park unit is located on the Crow Indian Reservation. <P3-S5>  Nearly one-quarter of the Pryor Mountains Wild Horse Range lies within the Bighorn Canyon National Recreation Area.