Y'Akama, and Point de Boise, or Entyatecoom,[97] from {284} the west, which take their rise in the Cascade range, and also its great south-eastern branch, the Saptin or Lewis, which has its source in the Rocky mountains, near our southern boundary, and being a large quantity of water to increase the volume of the main stream. The Lewis is not navigable, even for canoes, except in reaches. The rapids are extensive and of frequent occurrence. It generally passes between the Rocky mountain spurs and the Blue mountains. It receives the Koos-koos-ke, Salmon, and several other rivers, from the east and west (the former from the Rocky mountains, the latter from the Blue mountains)[98] and, were it navigable, would much facilitate the intercourse with this part of the country. Its length to its junction with the Columbia is five hundred and twenty miles.
The Columbia at Wallawalla is one thousand two hundred and eighty-six feet above the level of the sea, and about three thousand five hundred wide; it now takes its last turn to the westward, receiving the Umatilla, Quisnel's, John Day's, and de Chute rivers from the south, and Cathlatate's from the north,[99] pursuing its rapid*
