From Little Falls to Major Power Producer: A Brief History of Post Falls DamPost Falls Dam has stoically served northern Idaho for more than 100 years and is undoubtedly one of the major social and geographic influences in the region today. To appreciate the history of the dam, it is important to start at the beginning, before the dam was built, even before there was a Spokane River or Lake Coeur d'Alene. Before Lake Coeur d'Alene existed, the St. Joe River flowed through the present lake bed north and up through the Rathdrum prairie before turning west and into the Spokane Valley. About 15,000 years ago, during the height of the last glacial period, enormous glaciers covered much of British Columbia. This ice, which was nearly 4,000 feet thick, unimaginably covered all but the highest peaks. The glacier slowly crept into northern Idaho, stopping just north of Coeur d'Alene (Wuerthner, 30, 32). Ice dams in the Clark Fork area that supported glacial Lake Missoula actually caused some of the largest floods known to man. As the ice floats, these ice dams periodically rise and burst, catastrophically inundating the Rathdrum prairie in eastern Washington and northern Oregon. Locally, these floods brought with them glacial deposits and deep debris deposits that obliterated the St. Joe River that once ran through the Rathdrum Prairie. The southernmost edge of these deposits ended where Coeur d'Alene exists today, damming the old St. Joe River and creating Lake Coeur d'Alene (Alt and Hyndman, 73). The new lake received the entire flow of the Coeur d'Alene and St. Joe Rivers, more than could be absorbed through the gravel deposits, thus causing the lake to overflow and seek a new flow, now known as Spokane Ri ... ... middle of paper ......, Edward J. Kowrach and Thomas E. Connolly. Saga of the Coeur D'Alene Indians: An Account of Chief Joseph Seltice. Fairfield, WA: Ye Galleon, 1990. Print.Shiach, William S., John M. Henderson, and Harry B. Averill. An Illustrated History of Northern Idaho: Embracing Nez Perces, Idaho, Latah, Kootenai, and Shoshone Counties, State of Idaho. [sl]: Western Historical Publication, 1903. Print.Singletary, Robert. Kootenai Chronicles: A History of Kootenai County. Coeur D'Alene, ID: Northern Idaho Museum in Partnership with Coeur D'Alene, 1995. "Spokane River Hydroelectric Project" Print. Spokane River Project Hydroelectric Rehabilitation. Avista Utility. Network. February 27, 2011.LicenseApp.pdf>.Wuerthner, George. The Northern Idaho Lakes Region. Helena, MT: American & World Geographic Pub., 1995. Print.