April 2007 until April 2009, while the risk of allowing digging again was evaluated; 171 vials and at least a dozen incendiary devices were removed from the location. The salt plains were also used as a bombing and strafing range during World War II. Remnants of this use are still left on the plains. Recreation Driving tour: The Harold F. Miller Auto Tour begins near the nature center. It is long and ends at Highway 11. The dirt road passes by ponds and fields where crops for wildlife are cultivated. White-tailed deer and other wildlife are common. A trail of leads to Casey Marsh Tower, where waterfowl are abundant and bald eagles can be seen in fall and winter. Hiking: The Sandpiper Trail begins near the nature center and refuge office and leads to the edge of the salt flats and a birding observation platform. The Eagle Roost Nature Trail is a loop also beginning near the nature center. The trail goes through wooded and open areas, beneath towering cottonwood trees, past marshes and ponds, and to a shore and waterfowl watching area on Sand Creek Bay. Selenite crystals: A designated area of the of salt flats at the refuge has gypsum concentrations high enough to grow selenite, a crystalline form of gypsum. The selenite crystals found there have an hourglass-shaped sand inclusion that is not known to occur in selenite crystals found elsewhere in the world. Digging for crystals is allowed, but only from April 1 through October 15 to protect this vital Whooping Crane habitat. Hunting: About of the refuge north of Highway 11 are open for hunting. State laws apply, except deer may be hunted by permit only. Hunting is permitted for pheasant, northern bobwhite quail, mourning dove, ducks, geese, and sandhill cranes. Fishing: According to the U.S. Army Corps of Engineers, the extreme drought of 2011 and 2012 has almost ended fishing as a recreational activity at the refuge. These conditions caused very large fish kills in the reservoir and restocking has been suspended. Fishing downstream of the dam is still permitted, but is greatly affected by local precipitation and the flow of the Great Salt River. Information that follows indicate the practices in force prior to the 2011 drought, and may no longer apply: Fishing is permitted from April 1 to October 15 on most of the refuge. Closed areas are marked by buoys or