The Great Basin includes Nevada, the western half of Utah, a small part of southern Oregon and Idaho, and also a part of Southern California. It is a great interior basin with all its rivers draining into salt lakes or dry sinks. In recent geological times the Great Basin was filled with water, forming the great Lake Bonneville which drained into the Columbia River. In fact, the Great Basin is made up of a series of great valleys, with very level floors, representing the old lake bottom. On the bench lands are seen, in many places, the effects of the wave action of the ancient lake. The chief dry-farm crop of this district is wheat, but the other grains, including corn, are also produced successfully. Other crops have been tried with fair success, but not on a commercial scale. Grapevines have been made to grow quite successfully without irrigation on the bench lands. Several small orchards bearing luscious fruit are growing on the deep soils of the Great Basin without the artificial application of water. Though the first dry-farming by modern peoples was probably practiced in the Great Basin, yet the area at present under cultivation is not large, possibly a little more than four hundred thousand acres. Dry-farming, however, is well established. There are large areas, especially in Nevada, that receive less than ten inches of rainfall annually, and one of the leading problems before the dry-farmers of this district is the determination of the possibility of producing crops upon such lands without irrigation. On the older dry-farms, which have existed in some cases from forty to fifty years, there are no signs of diminution of soil-fertility. Undoubtedly, however, even under the conditions of extremely high fertility prevailing in the Great Basin, the time will soon come when the dry-farmer must make provision for restoring to the soil some of the fertility taken away by crops. There are millions of acres in the Great Basin yet to be taken up and subjected to the will of the dry-farmer. Colorado and Rio Grande River Basins