Lake Mason National Wildlife Refuge is located in the center of the U.S. state of Montana. The refuge has numerous lakes and extensive marshlands along Willow Creek, which provide nesting habitat for over a hundred bird species. Managed from the Charles M. Russell National Wildlife Refuge, the refuge is normally unstaffed and has few visitor improvements. The refuge is also divided into several separate sections, all of which form an integral part of the Charles M. Russell National Wildlife Refuge Complex.