soil, an abundant water supply, an intense sun, and an arid atmosphere unite to produce a rapid growth.

The development of this valley dates back only five years. It was claimed as a Spanish grant and the title was contested by local settlers, who were sustained by two decisions of the United States Supreme Court.

The people were poor and interest rates have been from 12 to 24 per cent annually, and as it is a new country investors have heretofore been inclined to regard the whole situation as a problematic venture. The settler, therefore, has practically had to rely on his own strength and endurance. Many have subsisted on corn bread and bacon while they constructed their canals and leveed their land by their own labor. Their irrigation works have largely been built without skilled engineering advice or experience, and are therefore defective in many respects. Four canal systems now cover a district that would have been more suitably served from one high-line canal. Some communities and groups of people have built fragmentary levees which should have been planned on an extensive scale to protect all. There are miles of levees on which no levels were ever run by an engineer, but which are true to grade, serving their purpose in a remarkable way. In one instance a levee, perhaps 4 miles in length, was holding where the water line was uniformly standing within 6 inches or a foot of the top of the embankment.

These people have expended their strength and their money in bringing this area to its present stage of development. Their canals are imperfect, their levees are not sufficiently secure, and their farms are not completely stocked. In this situation they are appealing to the Government, with which they desire most earnestly to cooperate, to construct a proper irrigation and reclamation system for their lands and adjoining public lands.

The flood of June, 1903, reached a height on the Yuma gage of 27 feet 8 inches. It was the highest flood for the last fifteen years. When the river reaches a stage of 24 feet 6 inches the water begins to overflow these bottom lands unless protected by levees. The maximum flood height ever recorded on Colorado River was on February 27, 1891, when a record of 33 feet 2 inches was attained. If arrangements can be made whereby the approaching flood waves in the Colo'rado can be observed at some point in northern Arizona and the information be telegraphed to Yuma, much loss and damage may be prevented. Many of the houses are adobe, and the overflow reaches their foundation and they soon fall.

It has not been found satisfactory along the Colorado River bottoms to depend on raising crops by planting immediately following the overflow, as American corn and grain do not mature with sufficient

rapidity and perish for want of water unless they are irrigated later. The valley must be supplied both with an irrigation canal system and with levees if it is to have its full or even approximate development. In their present financial condition these people are not sufficiently strong to construct these works for themselves, and are looking toward the Government for their salvation. That the land is productive has been demonstrated beyond question, and is fully illustrated in the photographs shown herewith. That adequate levees can be made has also been proved. The depth of water on these overflow lands usually does not exceed 4 feet. The small levees which have been built by the farmers are from 3 to 5 feet high and 5 feet wide on top. They hold in a way that is remarkable, restraining the flood, which is within 6 inches of the top of the embankment. The town of Yuma is protected by a levee built by the army engineers, which has stood in a satisfactory condition for many years. This levee is 10 feet wide on top, approximately 15 feet high, with slopes of 3 to 1 on the outer side and 1 to 14 on the inner side. These levees can not be expected to withstand a direct attack of the main current or body of Colorado River, but probably if they are constructed from a quarter to a half mile inland from the ordinary banks of the river they will be efficient. The depth of water against them would not exceed 3 or 4 feet, and the water overflowing the bottom is devoid of swift current. The soil in this bottom is a fine loam or silt, which is almost entirely impervious. In case the river encroaches upon the levee by the erosion of the river banks, it will be advisable to abandon it and build a new levee inland rather than to try to resist the direct attack of the river.

For the proper development of this section two things are needed: First, a high-line canal which will command by gravity all of the irrigable lands, the canals which are now constructed to be used if possible as the distributors of the main high-line canal. Second, there should be a substantial levee constructed from Yuma through to the Mexican line along the left bank of the river.

The bottom land below Yuma is typical of other portions of the Colorado Valley between Needles and Mexico. The overflow irrigation problems, character of soil, and the possible products are largely the same throughout. What has been learned from the hard experience of the colonists near Yuma should be applied intelligently elsewhere. The overflow problems must be met with substantial levees, but the difficulty and expense will be no greater than the construction of a distribution canal. The levees should be built well back from the river, to prevent undermining by swift currents and deep water, and also so as not to contract the river channel seriously. When the river does encroach upon them others must be built farther inland.

The same method of protection must be applied to other valleys of the river. The stream must be kept within its banks by grasses and willows planted along the sides and by spurs to deflect and guide the current. When the various reservoirs are established and the canals. are in operation it is to be hoped the problems of flood will be much more easily and much less expensively solved, and that the river can be maintained in a relatively permanent channel.

SILT.

The silt carried by the river presents a serious problem, as it accumulates and decreases storage capacity. On the other hand, silt is a valuable addition to cultivated lands. The following suggestion is made for the general solution of the silt problem. Low diverting dams should be constructed. These would afford a settling basin and the canals would then draw upon a supply partially clarified. A series of sluice gates in the dam would permit scouring out the accumulated silt for several hundred feet back from the dam. It is desirable to carry a small portion of the silt upon the land, to act as a fertilizer, but it is believed that silt will always be deposited in the farmers' laterals and necessitate cleaning at intervals. The silt in the ditches acts as a lubricant, however, and much smaller cross sections of canals and much less slopes are needed here than in other regions. Mr. D. J. McPherson has made an investigation of the subject and his results are being prepared for publication in the Water-Supply and Irrigation papers.

R. H. Forbes, of the experiment station at Tucson, Ariz., took daily samples of the water in the river at Yuma from January 10, 1900, to January 19, 1901, and has made complete chemical examinations of the samples, both as to silt and as to soluble salts. The following is a summary of the results for silt:

Silt carried by Colorado River at Yuma, Ariz., from January 10, 1900, to January 19,