 Work began immediately, with drilling for geologic investigation starting in July 1904 and continuing for ten months.Work proceeded concurrently on the construction of an access road up the narrow canyon from Cody.The chosen contractor, Prendergast & Clarkson of Chicago, started work in September 1905, building a camp for workers and starting on a diversion dam, which was to divert the river into a wooden flume, through a tunnel and out through another flume to rejoin the river bed.