National Geographic : 1907 Apr
SALTON SEA AND THE RAINFALL OF THE SOUTHWEST* BY ALFRED J. HENRY PROFESSOR OF METEOROLOGY, U. S. WEATHER BUREAU On February 11, 1907, the break in the Colorado River, which was described by Mr Arthur P. Davis, Assistant Director U. S. Reclamation Service, in the January number of the National Geographic Magazine, was definitely closed for the second time. A lake 440 square miles in area and 80 feet deep has been left. THERE is a growing belief in the extreme Southwest, and possi bly in other parts of the coun try, that the creation of Salton Sea is, in large part, responsible for the heavy rains of the last two years, not only in Arizona, but also in the Rocky Mountain states, and thence eastward over the plains. So strong is this belief that some persons have gone so far as to publicly advocate the maintenance of the present Salton Sea, notwithstanding the efforts now being put forth to shut off its supply. Like other popular fallacies, the present one doubtless arose from a careless con sideration of the facts in the case, failure to consider whether the supposed cause was capable of producing the observed result, and finally, a misconception of the physical laws under which moisture in the atmosphere is condensed and precip itated as rain. The facts, so far as they concern the purpose of this article, omitting all gen eral details which are already familiar to the public, are as follows: As early as October, 1904, there was some seepage water in the depression now known as Salton Sea, but no over flow water. In November, 1904, the De velopment Company completed a third intake on the Colorado River some miles below the first and second intakes in order to increase the supply of water for irri gation purposes. Soon thereafter a flood wave in the Colorado River scoured out the third intake so that it admitted more water than was needed. The surplus, which at times was very large, naturally sought the lowest part of the depression known as Salton Sink, and in the course of time Salton Sea was formed. It ap pears, however, that the increase in size of the so-called Salton Sea was gradual, and that it was not until October, 1905, that the total flow of the Colorado River was carried by various channels, mainly the Alamo and New rivers, into Salton Sink. The rainfall of October, November, and December, 1904, in southern Califor nia and Arizona was not out of the ordi nary, but beginning in January, 1905, and continuing throughout February, March, and April, an extraordinary amount of rain fell over a belt of country stretching from Florida to southern Cali fornia, and the region of heavy rainfall also extended into eastern Colorado, east ern Wyoming, western South Dakota, western Nebraska, and western Kansas. With the coming of summer the locus of heavy rains shifted to the states of Ne braska, Kansas, South Dakota, and Okla homa and Indian territories. September and October were generally dry months, but in November heavy rains fell in Texas, and thence westward to Arizona. December was dry. In 1906 practically the whole of that great region west of the ninety-fifth meridian received more than the normal rainfall, the regions of great est excess being central and western Kan sas, central and western Nebraska, all of South Dakota, Wyoming, Colorado, Utah, and central and southern Califor- * From The Monthly Weather Review.