Crescent Lake National Wildlife Refuge is located in the U.S. state of Nebraska and includes 45,818 acres (185 km2). The refuge contains the largest protected continuous sand dunes in the U.S. A dozen small lakes and numerous ponds are fed by underground aquifers in areas where the sand dunes are below the water table. Some of the dunes are covered in shrubs and grasses, while others are completely bare. After the end of the Pinedale glaciation, the Holocene glacial retreat exposed the sand dunes that had been deposited in their current location by the vast continental glaciers. This refuge manages the North Platte National Wildlife Refuge and together they form the Crescent Lake National Wildlife Refuge Complex.