RIVERS.—The Columbia claims the first notice. Its northern branch takes its rise in the Rocky mountains, in latitude 50° north, longitude 116° west; from thence it pursues a northern route to near McGillivray’s Pass, in the Rocky mountains.[96] At the boat encampment, the river is three thousand six hundred feet above the level of the sea (here it receives two small tributaries, the Canoe river and that from the Committee’s Punch Bowl), from thence it {283} turns south, having some obstructions to its safe navigation, and receiving many tributaries in its course to Colville, among which are the Kootanie, or Flat Bow, and the Flat Head or Clarke river from the east, and that of Colville from the west. This great river is bounded thus far on its course by a range of high mountains, well-wooded, and in places expands into a line of lakes before it reaches Colville, where it is two thousand and forty-nine feet above the level of the sea, having a fall of five hundred and fifty feet in two hundred and twenty miles. To the south of this it trends to the westward, receiving the Spokan river from the east, which is not navigable, and takes its rise in the Lake of Cœur d’Alène. Thence it pursues a westerly course for about sixty miles, receiving several smaller streams, and at its bend to the south it is joined by the Okanagan, a river that has its source in a line of lakes, affording canoe and boat navigation for a considerable extent to the northward. The Columbia thence passes to the southward until it reaches Wallawalla, in the latitude of 45° a distance of one hundred and sixty miles, receiving the Piscous, 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.