value of the present roads which would be submerged, and the estimated cost of constructing similar roads to take their place. The addition of these amounts gives a grand total of $226,028, the amount of the damages.

In conclusion it may be stated that some of the buildings, such as warehouses, shops, stables, and lumber storage, are probably larger than the needs of the agency require, as they were constructed for the Army which, at the time, required larger facilities in these lines than does the Indian agency. However, there are other features in connection with a modern, up-to-date agency which are not provided here, whose increased cost would about equal any saving due to decrease in size due to possible use of smaller structures for purposes named above.

Therefore, the total cost of reproduction, which will be the expense to the Government if the present plant is submerged, is considered fair.

Trusting that the above information may meet the requirements of the United States Army Board engaged in the investigation of the San Carlos project, I am, Very respectfully,

C. R. OLBERG, Superintendent of Irrigation.

ESTIMATE OF POSSIBLE DAMAGES BY SAN CARLOS RESERVOIR.

The COMMISSIONER OF INDIAN AFFAIRS,

SAN CARLOS, ARIZ., October 28, 1913.

Washington, D. C.

SIR: There has been submitted to me a copy of Indian Office letter of September 4, 1913, citation above, addressed to the Chief Inspector of Irrigation, which directs that a competent engineer visit this locality and make estimates of the damages which would result to the lands, buildings, etc., which would be affected by the San Carlos Dam and Reservoir, if built. The direction to the engineer is to make report jointly with the superintendent, "or separately if they can not agree." These indirect instructions were confirmed in a telegram to the superintendent, dated October 7, 1913. I agree with Engineer Olberg as to the value of the property within the proposed reservoir site and concur in his findings as far as they go.

In addition, I am of the opinion that a value should be placed on the dam site itself. It is properly an asset-and a very valuable one-of these Indians. When this reservation was set apart for the Indians the original orders, as far as I am aware, contained no exemptions whatever. Nothing granted to them should be taken away now without just compensation, or without their consent, voluntarily given.

In behalf of these Indians, notice is now given that the right of any authority to take any of their lands or other property for any purpose, without their consent, is denied. This phase of the question will be presented through your office at the proper time. Respectfully,

COMMENTS ON MR. OLBERG'S REPORT.

A. L. LAWSHE.

1. The board's project includes a road to run on the north side of the reservoir from the railroad to the dam. It is understood that if the Government will build bridges across the Gila and San Carlos Rivers, above the reservoir flow line, Graham and Gila Counties stand ready to construct a road between them. This will leave not more than 10 miles of road to be constructed, and reduces the item for roads to $10,000.

2. Mr. Olberg's estimated "cost of reproduction" of the buildings seems fair. But the new buildingss would be of more value than are the present ones, by the amount of depeciation noted in Mr. Olberg's report. The total of the depreciated values, which is $84,013, measures the real damages.

3. Regarding land damages it is the understanding of the board that this reservation is not owned by the Apache Nation. If the United States owns it, and if this irrigation project were solely for the benefit of the Pima Indians and entirely at the expense of the Government, it would be idle to pay damages except on improve31679°-H. Doc. 791, 63-2-10

ments belonging to the Indians, for the Government would be only transferring money from one pocket to another. But the project is also for the benefit of private lands that would receive a gift if the reservoir site be assessed at less than its value. Hence the project should pay for the land regardless of where the title lies. Mr. Olberg's prices on the various classes of lands are reasonable, and his estimate of land damages is accepted.

4. The estimates modified as indicated in these comments, are then as follows:

The value of the buildings owned by the white inhabitants is about $4,380; whether or not compensation should be allowed for these is doubtful. If allowance be made for moving Government stores and the effects of whites and Indians, and for contingencies, the sum total will not exceed $200,000.

APPENDIX I.

SILT DISPOSAL.

1. The mean annual flow is 346,568 acre-feet.

The percentage of silt is 1.3 per cent.

The volume of silt per year is 4,500 acre-feet, but it is estimated that about one-sixth would escape, leaving only 3,750 acre-feet in the reservoir.

The reservoir capacity to be maintained is 500,000 acre-feet.

2. With dam 160 feet high to spillway, the reservoir capacity is only 481,826 acre-feet. With a height of 170 feet, the capacity is 588,576 acre-feet, which is 88,576 acre-feet in excess of the 500,000 desired to be maintained. Hence either desilting or raising of dam higher than 170 feet would become necessary in 88,576÷3,750 = 24 years. With dam 180 feet high to spillway, the capacity is 709,626 acre-feet, or 209,626 acre-feet in excess of the 500,000, and desilting would need to begin in 56 years from date of construction, or 32 years from date of raising of dam.

3. The time (24 years) in which the dam of 170 feet would need to be raised is so short that it would be found cheaper to build to full height, 180 feet, at once, for with plant installed and force of men organized and experienced, it is probable that the addition would be made in the first instance for two-thirds of what it would cost at the later date. Besides, if the dam be not of the overfall type, there would be rock excavation for spillways for the lower dam, part of which would be not only useless in connection with the higher dam, but would necessitate expense in damming to the higher grade. The cost of such rock excavation as would be at the later date useless, together with the cost of damming the lower spillways, would amount to as much as the cost of the upper 10 feet of the final dam. Moreover, considering damages, the higher flood line around the reservoir would be at this time as easily and nearly as cheaply established as the lower one, whereas to raise the line at the later date would doubtless require removal of roads, habitations, and other improvements in the meantime established close to the lower reservoir as improvements are now being established on the floor of the reservoir.

4. While the figures show that with the higher dam storing to an elevation of 180 feet the capacity would not be reduced by silting to 500,000 acre-feet in less than 56 years, yet desilting had better begin at an earlier date, for by the earlier beginning the cost of desilting, including cost of desilting plant, would likely be better equalized, since in the earlier years the desilting could be suffered to be less in amount than the estimated 3,750 acre-feet per annum, while later, through gain in experience and probable improvement in methods,

the larger amount, 3,750 acre-feet, would likely be handled without increase in yearly cost. Another reason for earlier beginning is that silt would be less solidified than it would be in the deeper older deposit if no work were done for 56 years. A third and more important reason is that the irrigated lands will soon become in need of the fertilizing material. The date when desilting had better begin can not be foretold with certainty, but the Government should retain the power to execute the work at the expense of the irrigated lands whenever it shall deem such work advisable.

5. The location of the area to be desilted should be nearest the dam, abandoning the remote parts of the reservoir, for the principal item in the cost of desilting, whatever the mode, will be that of conveying the silt to the dam. The floor of the area to be maintained is assumed to average 10 feet above the present floor of the valley, partly on account of the irregularities in the topography which it would be impracticable to follow closely with a traveling plant and partly because, at any time, only a portion of the area would be down to grade, the remainder being "bank" of 10 to 20 feet on which to dredge more economically.

6. Considering the ever-changing height of reservoir water and the variableness of the amount of water to be discharged, it will be a matter requiring good judgment to determine from time to time just where the desilting plant should operate. A first thought may be that the plant should always hug the margin, following the shallow water down, in order to minimize the lift of mud, but this would result in finally having too extensive a level floor on which operations would have to suspend for want of sufficient depth of water long before the reservoir had become empty. Since the greater deposits will be on the lower levels of the reservoir, because the muddy waters will be oftenest there, desilting will sometimes need to be in depths greater than would be required for the mere operation of the plant. Matters thus far considered indicate that the bed of the maintained reservoir had better approximately follow the present floor of the valley.

7. The desilting operations would not be carried laterally into all the indentations of the shore lines or contours nor would they extend to the present 180-foot contour, for seldom would water be so high, and besides the plant would require a working depth of 10 or 15 feet. Hence the present 160-foot contours on the east and west sides are assumed to be the approximate lateral limits of the reservoir to be maintained, and the northerly limits, to provide a capacity of 500,000 acre-feet above a surface elevated an average distance of 10 feet above the present bed and below a plane 180 feet high, is found to be an east and west line passing 1 mile north of "agency tank" and crossing the San Carlos and Gila arms of the reservoir, embracing an area of 7,500 acres.

8. The center of gravity of the 7,500 acres is 4.7 miles from the dam, which would be the average haul in dredging uniformly over the bottom, though in practice this would be reduced perhaps to 4 miles, because floods occurring when reservoir water is low will convey much material toward the dam. Besides, floods will maintain some storage capacity beyond the limits of the 7,500 acres, which will obviate the necessity of extending mechanical desilting quite so far upstream.

9. Except for the item of haul, the annual cost of desilting would be independent of the amount of reservoir capacity to be maintained, but the larger the capacity the earlier need be the date of beginning.

10. Desilting is a leading problem involved in the project. From time to time various plans have been proposed. One plan was to have irrigation water discharged through the dam at river bed level; but it is known that with water in the reservoir, the influence of the low outlet in removing silt would extend only a few hundred feet upstream, for the velocity of approach would be so low. Nevertheless there should be an outlet at river bed level for use whenever the river is flowing through an empty reservoir.

11. Another proposal was to have the river flow through empty reservoir and low outlet long enough to excavate for itself a deep bed through the silt deposits, which it would do in time through recession of waterfall; and a bottom width of 200 feet and side slopes of 1 on 4 have been assumed to result from such process. But that would give but a fraction of the reservoir capacity desired to be maintained. If a very large amount of silt were removed in a short time the current in the river bed below the dam would not be able to convey it all.

12. A plan of general merit, outlined in Irrigation Paper No. 33, is to construct a canal of about 300 second-feet capacity above the margin of the reservoir, which, while the river flows, would furnish water at a high constant head at the dam for power, and the canal water would divert some silt from entering the reservoir. It was proposed to have the upper reach of the canal of greater capacity to receive a larger fraction of the river water. In this reach partial settlement of silt was anticipated and the topmost clearer water was to spill over bank of canal to be stored in the reservoir, while the remainder, surcharged with silt, would pass down the canal. In the mind of another, such canal was to serve the further purpose of supplying water under good head for sluicing silt out of the reservoir when empty. At that time it was contemplated to have the reservoir empty quite often, for it was to hold only half of the expected annual flow, just to equalize the supply within an irrigation season. Were the reservoir empty each year during the three or four muddy months, only a quarter of the year's silt would be impounded.

13. Another writer proposed using canal water to operate hydraulic giants to be installed on projecting spurs to accomplish desilting, but only a small fraction of the reservoir could thus be reached.

14. The growing thought of larger storage for longer periods from times of plenty to years of drought makes the reservoir empty so seldom and for times so short that giants and ground sluicing could be at best but partial remedies.

15. Yet the thought of high-level marginal canal remains attractive partly because it would divert some silt and partly because it would provide during much of the time a higher and more constant head for generation of power than will the fluctuating reservoir waters. Considering only the hydraulics in the case, an improvement would be to make the canal several times as large, to carry even the smaller floods, and provide for escape of excess water with its silt into the lower end of the reservoir where the silt would be afterwards most