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V Mr. Charles P. Jquires, 408 3o. Jeventh St., I,as Vegas, Nevada. Dear !¥. Souirea: Thank you for your two recent letters in which you asked me to clarify certain points not fully covered in ny short report to ”r. '.'.axfield. Your questions are much to the point and as you say, others have also asked the same questions, so I shall have this communication duplicated for your convenience. Until detailed studies are completed I shall refrain from the release of specific cost or quantity figures le3t I should add to the bulk of the accrued confusion. The ,/ater .Exchange Concept is amenable to pre­liminary analysis without precise figures. The ./ater Exchange Plan is a normal and nroper approach to a regional water supply nroblem; it provides for two sources of supply which will normally be available to everyone. The industries will have first call on an increased .amount of I.ake water plus water from the Artesian Basin in the event of failure or disaster. The resident population of the Valley will have first call on the Artesian Dasin supply, and by the use of supplemental Lake water will be able to conserve and maintain a sufficient reserve in the subterranean basin to assure the continuous operation of the Government-owned plants in the event of any temporary failure of the Lake water supply system. The resident copulation needs supplemental Lake water; once the natural reservoir is stabilized their requirements need not be continuous or on a demand basis, and there will be no need for encroach­ment on the prior rights of the industries. a ./ith relatively simple alterations the capacity of the existing water supply works can be greatly increased. That means that the works can earn greater revenue and that there should be some saving of water Cost to all of the consumers. In good waterworks practice an auxiliary source of supply is a must when it is economically feasible. In this case it is less costly to provide for an ideal condition and it would be incongruous to operate two supply systems from the Lake when one can accomplish so much more at so much less cost. The Jtate Engineer’s Office and the U.3. Geological .Survey have made extensive and excellent investigations of the Hydrology of the Las Vegas Valley. It is estimated that withdrawals from the artesian basin during the past seven years have exceeded the average rate of recharge. If withdrawals are reduced to less than the recharge rate and the deficiency is satisfied by the importation of Lake water the basin can be restored to,