As used in this chapter, (a) all terms which are defined in the Colorado River Compact shall have the meanings therein defined;

((b)) “Main stream” means the main stream of the Colorado River downstream from Lee Ferry within the United States, including the reservoirs thereon;

((c)) “User” or “water user” in relation to main stream water in the lower basin means the United States or any person or legal entity entitled under the decree of the Supreme Court of the United States in Arizona against California, and others (376 U.S. 340), to use main stream water when available thereunder;

((d)) “Active storage” means that amount of water in reservoir storage, exclusive of bank storage, which can be released through the existing reservoir outlet works;

((e)) “Colorado River Basin States” means the States of Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming;

((f)) “Western United States” means those States lying wholly or in part west of the Continental Divide; and

((g)) “Augment” or “augmentation”, when used herein with reference to water, means to increase the supply of the Colorado River or its tributaries by the introduction of water into the Colorado River system, which is in addition to the natural supply of the system.