What is true historically is also true prehistorically in that habitation and fishing sites tended to cluster along the lower terraces of the Columbia and Spokane Rivers, which are now inundated by Lake Roosevelt. Many lower terraces in the upper reservoir become exposed during drawdowns. Higher lake levels protect submerged archeological resources, which suffer potential exposure when drawdowns make them accessible, not only legally to archeologists undertaking excavation and data recovery, but also to looting and damage from vehicles illegally driven on the drawdown. About 200 archeological sites have been identified. The sites range from pictographs and petroglyphs to habitation and fishing sites and other evidences of human occupation, including cobble tools or modified core tools often found on upper terraces.
Many sites are surface scatters with little depth, although some sites do have considerable depth.
Much is known, therefore, about the types of sites that occur and about their patterns of form and distribution, both prehistorically and historically. Both the rock formation that created the falls and the fort site are now submerged under the lake. St. Paul's Mission is the only intact historic structure associated with early Christian evangelism among Native Americans known to exist within the Lake Roosevelt basin. . . . The chapel at St. Paul's, built in 1847, was originally accompanied by a residence and outbuildings, none of which remain. Fort Spokane served from 1880 to 1899 as a military fort to keep the peace on a dwindling Indian frontier.