This combination of file photos provided by the Nebraska Department of Natural Resources, shows the Spencer Dam near Spencer, Neb., in November 2013, top, when it was holding back water on the Niobrara River and again in March 2019, after the dam failed during a flood. The dam that collapsed under pressure from an icy flood had a history of unaddressed ice issues and had no formal emergency plan because regulators wrongly assumed that no one would die if it failed, according a report released Tuesday April, 21, 2020. (Nebraska Department of Natural Resources via AP)