An eastbound Union Pacific freight is on the long trek across Great Salt Lake at Lakeside, Utah, on March 5, 2012. A 12-mile wood trestle used to carry the railroad straight across the lake, but during 1952-59, Southern Pacific replaced it with the fill that the train is negotiating zig-zagging to the north. Promontory Peninsula and the Wasatch Mountains dominate the background, with Ogden located between them. Over the years, reduced circulation of the north arm of the lake due to the fill caused it to become much saltier than the southern portion. The south arm is fed fresh water by three major rivers causing the imbalance. To mitigate this problem, UP recently announced that they were going to cut in a new 180-foot bridge on the earthen causeway to be completed by the end of 2016.