As the worst drought since 1956 gripped the nation last year, lakes and ponds slowly receded, revealing decades worth of dropped and discarded fishing tackle, pop cans and all sorts of flotsam. At Oak Lake in Lincoln, the debris included at least two guns. A person walking along the edge of the lake last summer spied a suspicious item and called Lincoln police, who found a handgun rusted beyond recognition. “That thing could have been in there for 50 years for all we know,” said Sgt. Ben Miller. After that gun turned up, officers Kevin Hinton and Jen Mullendore couldn’t...