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Show v o O JJZ - Lake Does Not Influence Weather Conditions Has Lake Mead over 100 miles long and the largest man-made body of water in the world exerted any influence on the weather and climate cli-mate of America's driest desert, in the heart of which it was created by construction of Boulder Dam in the Colorado River? This question, about which there has been much speculation, now can be answered, "Emphatically, no." "Lake Mead was not expected to influence the weather of the south-jwest," south-jwest," John C. Page, acting commissioner com-missioner of the Bureau of Reclamation, Recla-mation, said today. "It has not done so and it will not." An investigation was begun last summer when unauthoritative statements state-ments were circulated that perceptible percept-ible changes in the climate and weather were resulting as Lake Mead grew behind Boulder Dam. The Bureau of Reclamation had calculated calcu-lated in advance the rate of evaporation evap-oration from Lake Mead which could be expected. These calculations calcula-tions indicated that insufficient moisture would be lost to cause a noticeable alteration in weather conditions. con-ditions. A series of tests are now underway to check precisely the amount of evaporation actually occurring, oc-curring, and while the records obtained ob-tained are too short to be conclusive, conclu-sive, they indicate the calculations made in advance will be' found to be closely accurate. Not wishing to await the conclusion conclu-sion of these tests, information was sought by the Bureau of Reclamation Reclama-tion from residents near Boulder Dam, from airplane pilots who fly over Lake Mead each day, and from meteorologists of the United States Weather Bureau at Phoenix. Arizona, Reno, Nevada, and Salt Lake City, Utah, who are in charge of the weather records of the vast area surrounding Lake Mead. J. Cecil Alter, meteorologist for the Weather Bureau at Salt Lake City," summed up the evidence obtained ob-tained with this observation: "By comparison, the water in a pitcher on a fn"?vr's 't-nd is about as effective in P''--""'-dition-ing an auditorium as LaVi Mead is in modifying the climate." Seventeen pilots and co-pilots of a great western air line which tends planes daily across Lake Med were questioned. Fifteen reportei they hd noticed no change in atmospheric atmos-pheric conditions. Two said that they believed the time which has elapsed since L"ke Mead b-grn to form in February 1036 was f-no ,-hort to make any change evident. Residents near Builder Dam and in cities clore by the lake $aid they hnd noticed no difference in the clim?te. v George V. S?pw, associate meteorologist meteor-ologist of the Weather Bureau of Reno, said, "The creation of Lake Mead has had no appreciable effect ef-fect on the climate of southern Nevada." Ne-vada." Summer rains over southern Nevada Ne-vada are generally thundershowers. Masses of moist air from the Gulf of Mexico move inland over Mexico Mexi-co and thence into Arizona and New Mexico during the summer, commonly com-monly resulting in intense local storms of cloudburst proportions. "The rains of the southern and and eastern portions of Nevada this vear in August were of this type " Mr. Sager aid. "When the ares of Lake Mead is c-mnared with the thousands of square miles over which such "hewers are distributed and when the fact that the vapor of evaporation from the lake surface sur-face is being constantly carried away and mingled with dry a'.v ever a vast area, is taken into account, it is at once apparent that no imnort-ent imnort-ent effect on local rainfall is likely ' to be found." Walter B. Hare, meteorologist of the Weather Bureau of Phoenix, said it was possible that humiditv within a radius of a few miles of the lake might be raised sufficiently sufficient-ly to be noticeable in records kept over a long period of time but that the effect of Lake Mead on the climate cli-mate otherwise would be n??ligiblp. "Circulation of the atmosnhere is such." Mr. Hare aid. "that mu"h of the moist pir risinr from fh" lake will be carried entirlv out of the state of Arizona. Mc-e"ver, regardless re-gardless of the direction of IN movement, move-ment, it will becom" so d'ffured ,and scattered over such a wid" a'-ea that its influence will be reduced to a minimum." In the opinion of M-. t-r stationed sta-tioned at Salt Lake Cit''. t ,ve iyrcacl does not exert any arnrc-inblo influence in-fluence on the climate, even of its A - Jyy V y t , 0 V immediate surroundings. He quoted the weather records of Utah showed deficient precipitation during several sever-al months since Lake Mead has grown to be the largest artificial lake in the world. During other mcnths of this period precipitation has been greater than the normal. "These same variations could undoubtedly un-doubtedly have been expected," Mr. Alter said, "had there been no Boulder Boul-der Dam, as they are considered to be entirely within the control of thr usual precipitation producing influences." in-fluences." "Construction of Boulder Dam and creation of Lake Mead has ex- rv erted and will continue to exert a J ji great influence on the Southwest," f Mr. Page said. "The character of j j the Colorado River below Boulder L Dam has been changed entirely from JS'--an erratic stream to a perennial TT" stream on which irrigators can rely J,S. confidently. The contributions made " by Lake Mead through control of floods and dthrough increasing the ' flow of the river during summer f'T droughts have added to the security of tens of thousands. No magical influence on the climate of the j y Southwest has been claimed for this i project and none is necessary 'to Its V complete justification," j J |
