N the early development of a country rivers are useful mainly as avenues of travel. They are highways to the interior which lure the adventurer and the pioneer. Later, when the land becomes settled, they may or may not retain this primal use. Now protection is demanded from the ravages of the river, and the property and the life of the riparian settler must be safeguarded. Later, when great cities grow in the basin, heavy demands for water for domestic purposes arise; and power for lighting, transportation, and manufacturing is called for. Of all the uses of the river, which are paramount and which are subservient? If two or more can be developed, which should have the preference? Under what conditions do the uses of a river conflict?