Early water transportation on the Upper Mississippi River from St. Paul to St. Louis was hindered by fluctuating water levels. In 1878, the Corp of Engineers studied the impact of a reservoir system on the river, and the study resulted in the building of six dams between 1881 and 1912. The first dam was constructed at Lake Winnibigoshish and the last at Gull Lake; at Big Sandy Lake, the dam was built in 1895. It was hoped that the dams and their respective reservoirs would maintain a water level high enough to allow steamboat navigation in the summer. Controversy arose from the start, as railroads and lumbering interests feared the reservoir system would impede their trade, and Native Americans found that the harvest of wild rife was also affected because the raised water levels hindered the growth of the plants themselves. The project did allow steamboat traffic between Aitkin and Grand Rapids and benefited the mills at St. Anthony Falls in Minneapolis, but navigation did not improve fully and river transportation did not blossom until a series of locks and dams were built on the Upper Mississippi between St. Anthony Falls and St. Louis from 1917 to 1940, after which barges replaced steamboats on the more dependable waterway.