ARID REGION RAIN-FALL AND VARIATIONS. 107 volved and "scientific" in character that the "plain" people may not understand them when properly informed. In regard to high altitude work it must be borne in mind that what we now really know of the precipitation over the whole of this region relates more to the valleys and the table-land than to any other part. All meteorological or weather service reports have been simply for the purposes of local trade and traffic. We have had no system of observations of a definite and distinct character in regard to the mountain ranges. The rain chart presented in the last census by Mr. Gannet, and which has been improved by later observations, shows the only record that of rain-fall definitely from the ninety-eighth degree to the Pacific Ocean will range from 34 inches at certain points, as at Yuma and on the Colorado Desert, or going from the east to the west, from 20 inches down to 8 and 9 in the basin, and up again to 18 and 20 or 24 on the Pacific coast. It is known as a matter of fact, though not as a recorded series of observations, that the rain-fall and snow precipitation on the mountains is from 30 to 60 inches in excess of what it is in the valleys below. The average snow-fall on the Sierras will be from 60 to 70 feet of loose snow, giving us on the basis of 11 inches of snow to 1 of water from 5 to 6 cubic feet of water. All, or nearly all, of this water runs to waste. At least 40 per cent. of it passes away in evaporation, and the remainder into the ground. Probably the largest portion disappears below. The United States Irrigation Survey reports up to the close of 1889 the storage capacity of reservoir sites so far surveyed to be as follows: From the statement made before the Senate committee by the Director of the Geological Survey of the total amount of lands "selected" as irrigable in the following States and Territories, the following figures (in acres) are given : New Mexico, on the Rio Grande and Rio Grande Valley.. 5,200,000 Total.... FOREST TREES AND THEIR CONSERVATION. 7,000,000 31,600,000 The subject of forestry is a part of the investigation of the question of the irrigation of the arid region and its importance can not be overrated, for "it is the discovery of a new continent, by knowledge, skill, science, and art." Possessing 75,000,000 acres of forests, little or no attention has been paid to the subject until very lately, and that only tentatively, by Congress. Our forests are wasted by fire and neglect, which by a judicious and economical management could be conserved and in creased, and by their conservation and increase humidity will follow with new areas of rain. Trees act as a protection from the dry winds, and when planted and cultivated in narrow belts of timber shelter the crop from the wind-break and lower the rate of evaporation. The following table, condensed from the report of Mr. B. E. Fernow, chief of forestry division in the Department of Agriculture, approximates the ratio of mountain land and plains and gives the forest area: Mountain forests equal 22.23 per cent. of mountain area. Little has been done in forestry planting. From the same report of the chief of the forestry division the following condensed statement shows the number of entries under the timber-culture: Total number of acres entered from 1873 to 1888, inclusive... Total number of acres on which final proof was made, or 8 per cent. of Total number of acres planted 38, 958, 558. 45 9,346, 661. 03 784,037.23 ...784, 037-16=49, 002 Total number of trees declared to have been planted and cultivated..... 38,076, 350 or less than one tree for each acre entered for timber culture. The valuable report of B. E. Fernow, chief of forestry division of the Department of Agriculture, bristles with facts upon this most important subject, the handmaid of practical irrigation. The intimate relation of the forests to the water supply necessary for irrigation will soon force itself upon the consideration of those living in the Rocky Mountain region, and it is well set forth in a recent statement of Mr. Nettleton, State engineer of Colorado, who says: It is estimated that 60 inches of water fall annually on the eastern slope of the Rocky Mountains in the form of snow and rain; 80 per cent. of this falls during the winter and spring months. That which falls late in the autumn and early in winter is most available for irrigation, as it becomes solid, almost like ice, and melts slowly under the summer's sun, affording a steady flow through the irrigating season. Snows falling in late spring melt rapidly, and the waters run down the rivers unused. Although about fifty mountain peaks in Colorado reach an elevation of over 14,000 feet, yet the snow nearly all disappears every season, small quantities only remaining in SUMUING UP OF ENGINEERING PROBLEMS. 109 small patches here and there. On this account there are at present no glaciers in the Rocky Mountains. The cold mountains condense the moisture in the country adjacent, thereby robbing the plains of their quota of moisture. Hence the necessity for irrigation. It is quite easy to foretell the probable amount of water for irrigation purposes for the coming season by watching the amount of snow-fall in the mountains. Farmers living from 20 to 30 miles from the mountains, or where they can watch the snow-fall on the main range of the mountains, have learned to gauge their crops by the time the snow falls and the quantity. If the snow falls early, they expect water for late crops. If the snow falls principally in the spring mouths, they fear short water in summer and fall, and plant or sow accordingly. There can be no doubt about the influence that cutting or burning the timber on the mountains has on the flow of our streams. They will on this account become more intermittent in their flow, which is a drawback to the irrigation interests of the State. The preservation of the mountain forests should be encouraged. To sum up simply, then; the questions concerned and issues involved in the reclamation of our arid West, may be stated in the following propositions: First. The use of the rain-fall in what are properly known as rain belts, by the most effective methods of cultivation, and the selection of suitable plants, especially those with long tap roots. Second. The exhaustion of the supply furnished by rivers and creeks in their passage through the drains, by means of irrigation works, such as are already in extensive use. Most of our streams can be used up to the full amount of their annual discharge. Third. The enlargement of the existing supply by the storage at higher elevations of water which passes away in spring floods. The building of numerous catch-basins throughout the plains to save the rain-fall which is wasted, so far as the lands near by are concerned, will add greatly in the supply furnished by running streams. There are natural depressions everywhere which can be utilized at very slight cost, and with entire immunity from risks of dangerous floods. Congress has already surveys to ascertain the most available sites and methods for accomplishing this plan. Fourth. The sinking of galleries or tunnels below the surface of streams, even when they are practically dry, and utilizing by canals the underground currents. Pure filtered water at Cheyenne, Wyo., for the supply of the city, without pumping or much expense, is so furnished from a small stream nearly dry in summer. The utilization of surface water does not exhaust the supply for irrigation. The application involves waste. The fugitive waters sinking into the ground pass into the depressions which make the water-ways, and gradually swell the scanty streams at lower levels, or course their way toward the sea through the sands below the river beds. Thus a part of the water of irrigation canals is gathered a second time to do the work of irrigation. Fifth. By the use of stationary pumps of sufficient power, in lifting such underground currents to the surface from bed-rock, for application to surrounding lands. Sixth. By artesian wells, which have hitherto proved too expensive for use in irrigation. To these six may be added the small storage or farm tank system, which can be effectually utilized on our plains region. IRRIGATION CONSTRUCTION. ITS PLANS, PROJECTS, SYSTEMS, WORKS, FORMS, CONTRACTS, AND MANAGEMENT, PRESENT AND PROSPECTIVE. PART III. PROJECT FOR A DAM ON SALT RIVER, ARIZONA. Mr. Wm. M. Breckenridge, county surveyor of Maricopa, presented a plan to the Senate Committee. He said the location settled on is at the mouth of Tonto Creek, a little above the mouth of Mazatzan Cañon. Mazatzal range cuts through the Upper Salt River. It makes a big cañon, with mountains on each side 1,500 feet high. The slope is one to one; that is, perpendicular for 100 feet. The water is thrown back eastward 16 miles on the Salt River, where it boxes again in the Sierra Ancha. For the first 2 miles from the mouth of Tonto Creek, point of construction already suggested, the average width is 2,640 feet, and the average depth would be 180 feet, calling the proposed dam 280 feet high. The next 23 miles opens out into a valley, the average_width being 2 miles and depth 140 feet. The river then narrows up at Steamboat Rock, 43 miles above, so that it is only a quarter of a mile wide, with an average anticipated depth of 130 feet. Then above the Steamboat Rock passage for the next 103 miles the average width is 2 miles, and the average depth will be 70 feet. Tonto Creek, with a width of 14 miles, could be made to obtain an average depth of 80 feet. There is ample space at a box cañon coming in from the south, where a wasteweir could be built, so that the river, when it arrived at a certain height, might run over that and not into the dam. By it, enough water can be stored to reclaim all the desert mesa land lying north of the Gila River between Phoenix and the Colorado River at Yuma. Sufficient quantities of water annually flow through the Salt River to fill this reservoir several times. It is our belief also that, by the selection of suitable reservoir sites along the Gila, water enough can be stored to reclaim all the lands south thereof in this county. The Agua Fria, where it enters the Salt River Valley, in the dryest season carries a stream of several thousand inches of water. If properly utilized there is sufficient in this river to irrigate all the land, some 75,000 acres, lying between it and Cave Creek, and by a reservoir the land could be made available. THE PROPOSED PANTANO RESERVOIRS. Engineer F. W. Oury, of Tucson, Ariz., outlines an extensive project for dams, reservoir, and diverting, at a point on the Southern Pacific Railroad, a few miles from Tucson. He says: Location. The sites for the proposed dams are located on the water-course commonly known as the Pantano Wash. Dam No. 1 is situated at the junction of the Cienega and Davidson's Cañon, about 23 miles southeast of the city of Tucson, where |