Claim: Grays Lake National Wildlife Refuge is a 19,400 acres (79 km) wildlife refuge and largest hardstem bulrush marsh located in Bonneville County, Caribou County, Twin Falls, Idaho, United States, that was established in 1965.
Evidence: 19,400 acres (79 km) Grays Lake National Wildlife Refuge is a National Wildlife Refuge of the United States located in southeastern Idaho. It has the largest hardstem bulrush marsh in North America. Bonneville County, Caribou County, Idaho, United States 1965