Before settlers moved into the basin, it consisted mainly of upland and wetland forests in which Native Americans fished, hunted, and foraged. Evidence suggests that people lived in the northern Oregon Cascade Range as early as 10,000 years ago. By 2,000 to 3,000 years ago, settlements in the Clackamas River basin, adjacent to the Johnson Creek watershed, had moved to the river's lower floodplain. The area was the home of the Clackamas Indians, a subgroup of the Chinookan speakers who lived in the Columbia River Valley from Celilo Falls to the Pacific Ocean. The Clackamas lands included the lower Willamette River from Willamette Falls at what became Oregon City to its confluence with the Columbia River and reached into the foothills of the Cascades. When Lewis and Clark visited the area in 1806, the Clackamas tribe consisted of about 1,800 people living in 11 villages. Epidemics of smallpox, malaria, and measles reduced this population to 88 by 1851, and in 1855 the tribe signed a treaty surrendering its lands, including Johnson Creek.