Johnston, Iowa - The U.S. Army Corps of Engineers has announced that Jenson Construction Company plans to begin mobilizing construction equipment & material at the Big Creek Diversion Dam in the next 2-3 weeks. During various stages of mobilization and construction, access into Big Creek State Park from Broadway (Old Hwy 415) and across the dam will be limited to one lane with traffic controls. The Neal Smith Trail will be open, but will merge with the one lane traffic across the dam.