The San Poil and Nespelem Indians long before the coming of the white man inhabited the Okanogan County portion of the Grand Coulee Dam area. According to older Indians, numerous Indian villages existed along the Columbia River, including a summer settlement at the mouth of the Nespelem River, another across the river from the Barry post office (Steveson ferry), and a fishing grounds across the river from the mouth of the Grand Coulee.

Nespelem and Keller became permanent communities after the Colville Indian Reservation was established. One old time Indian who will always be remembered was Sally Iswald Keller, reportedly 112 years old when she died at Malott December 26, 1957. Until a few years before her death, she was a familiar figure in Coulee Dam and Elmer City, jogging unhurriedly along on an ancient white horse, sometimes selling huckleberries, sometimes traveling from her summer camp near Keller to Nespelem, and sometimes going nowhere special.

From the early days of the reservation, the Indians held two major gatherings each year. The Salmon day celebration at Keller, in late spring, and the Fourth of July pow-wow at Nespelem.

The Salmon day celebration that has occurred only spasmodically since the formation of Lake Roosevelt was held at the original site of Keller, a few miles upstream from the mouth of the San Poil River. It included a rodeo, wild horse races, public and tribal dances, and a generous supply of unscheduled entertainment.

The Nespelem pow-wow frequently lasts for as long as two weeks, with Indians arriving from other reservations in Montana, Idaho, Washington and Oregon as early as July 1 to set up their tee-pees in the "Circle" and prepare the longhouse for the feasts and tribal dances. In the parades and dances, one sees many traditional costumes, some actually worn by Nez Perce and other warriors in battle. His grandson, George Friedlander, has brought Chief Moses' ceremonial costume. There were many women's buckskin dresses.

Until the last few years, the mournful keening of Indian women in the tee-pees singing the tribal death chants as the parade in slow review around the Circle offered a never-to-be-forgotten experience. Along with many other ancient ceremonials, these death chants, which honored the fallen warriors symbolized by costumes worn in the parade, have been largely discontinued. Although the traditional rites are still observed to mark the passing of the elders, such as Minnie Poween Yello Wolf, one of the last survivors of the Lolo trail retreat, whose death in 1955 brought Nez Perce tribesman from several other reservations to Nespelem for the full ceremonial rites.