Staff at Lock and Dam 4, in Alma, Wis., hosted an open house – attended by more than 600 people – on July 28, 2018. The doors were open for the curious to explore the lock house, lock walls and even the structures atop the dam that house the machinery used to operates the roller gates. Those in attendance were also able to see several recreation vessels lock through and, shortly after noon, witnessed the Motor Vessel Show Me State lock through 12 barges on its way downstream!